A few days ago we were at the Manchester Caravan & Motorhome show and we think that finally we may have found our next caravan. I posted on Twitter couple of photos and said something along the lines of “Now anyone that reads the blog will know we have been looking for a new caravan for the last couple of years and finally the @CoachmanCaravan Laser 665 ticks nearly all the boxes…“
A follower on Twitter – Venomator @Venomator tweeted back “I would be very interested to know what box/es remain unticked then?…” so this is a bit of a reply really.
One of the biggest things I have been looking out for on any caravan or motorhome is a sticker announcing that the charging systems installed are suitable for Lithium chemistry batteries. So many people have been asking me recently about changing over to Lithium and what’s involved… well quite a lot actually. There is not that much difference between a motorhome or a caravan when it comes to changing over to Lithium.
The existing shore power charger built in to most motorhomes and caravans is not lithium friendly and will probably result in either damaged lithium cells or a battery that is never really charged. So the inbuilt charger will need to be swopped out.
The solar chargers on most (not all) leisure vehicles can’t be programmed for lithium, so that will need to be replaced. And finally the vehicle charging system, which currently on most production leisure vehicles be it motorhome or caravan is not suitable for lithium batteries so a DC to DC charger will need to be installed.
All this adds up to a bit of a job and a fair chunk of beer (or wine) tokens on top of the price of a Lithium battery. I have seen lithium batteries that are advertised as direct replacements and can be dropped in place of an existing Lead acid wet cell or AGM battery but this would imply that they have charging circuits built into the battery and careful research shows the same battery and part number offered by a different vendor with no such claim to be ‘drop in’ replacements. So beware.
As I really wanted to start off a new van with a lithium set up (I can get around 360Ah of lithium for the same weight as 110Ah of good quality lead acid) but the down side is I’d have to virtually rewire the charing side of a new caravan. I eagerly await one of the big caravan manufactures to offer a “Lithium Ready” product and maybe they would like to use my label!
I don’t think it would be that difficult to achieve and due to production volumes, the additional cost would only be marginal. I expect that (or hope!) that one of the aftermarket companies such as Sterling Power or RedArc would offer something that might be a cost effective ‘box’ to achieve a changeover.
So what else was on our unticked list?
I still would like caravan manufacturers to actually go out and look at a site full of caravans being used. I can’t understand why they don’t move the electrical hook up and water at least behind the axle so it would be closer to where the EHU post is. One thing I find is having a VW Amarok which is one of the widest pickups on the UK market, on some pitches if we are using the Aquarol it’s damn near impossible to squeeze down the side. Moving everything to the rear would make it so much easier… well for us it would.
While I’m on the subject of EHU’s & water connections…. Instead of cutting lots of small holes in the sides of our vans for water and 16 amp connections… do what our American cousins do… locate everything in one locker and save on the routing out holes in the sides and adding plastic doohickeys with sliding or hinged covers. I do like the fact that some caravans now have the battery stored in a floor compartment.
The other one that missed the tick box was the lack of being able to sit in front of a mirror…
Not a deal breaker for me… but Sue thought that if they had made the mirror so it could swing round either way to face each bed that would have been ideal. Some of Swifts offerings have got it spot on with a mini dressing table. Coachman however have conveniently located a socket for hair dryer/straightners. I did wonder about having a small stool or seat spanning across the two beds… but think the mirror swivel is a much better idea. Maybe it’s something that could be added as an after market item using a swivel TV bracket maybe”
Now… anyone know where I can buy some cheap lottery tickets…. hello… anyone….
My email box tends to get a wide variety of questions covering all sorts of subjects. The most frequent one is to do with wiring and electrically related problems. Sometimes trying to diagnose issues via email and a few photos is a bit of a challenge, but hey who doesn’t like a challenge! One thing that I do see a lot of is electrical work that is…. well, quite frankly not up to scratch in my opinion. So here is my attempt at a basic guide.
You have to have a plan.
So many projects start by adding one or two things… extra 12 volt outlet here… maybe another light and then something else comes along that needs adding in. Before you know it you have a mess of spaghetti that the local Italian restaurant would be ashamed of. It is all too easy to fall into the trap of adding circuits to existing fuses…. or installing a new fuse and a few weeks later adding another circuit to it as it’s easier than installing another fuse.
You can download these and other drawings from the Electrical Drawings page in the drop down menu under “Document Library”
You need to draw out how the major elements are going to connect together – leisure batteries, solar charger, DC to DC charger, inverter and include all the big fuses, buss bars and fuse box. Don’t think about where any of this goes for the moment just get the basic layout and how everything interconnects worked out. It might take a few goes but paper is usually cheaper and less frustrating than sorting out the mess afterwards.
Once you have all that figured out you can start working on the details… just how many fuses will be needed… and what ever number you come up with add half as many again as a minimum. Having a few spare fuse positions that maybe never used is way cheaper than in twelve months time having to install an additional fuse box. A this point you can start adding details…. what size cable is needed for each link, what sort of fuse box do you need.
You can also now start to think about specific facilities you might need. For example, many overlander vehicles will have a button on the dash that when pressed and held down activates a high current relay that links the house batteries to the engine cranking battery. Very handy to have… jump leads are not much use if you are 200Km from the nearest vehicle. If your only trip ‘off road’ however is the muddy car park at the local car boot sale than maybe not a priority.
Don’t use the vehicle chassis as a ground.
Modern vehicles are constructed using different materials and quite often panels and sub frames are glued together. Back when virtually all the panels were spot or seam welded steel, using the body and chassis as a ‘ground’…. which really isn’t a ground but the neutral return path… this was acceptable. However now, sections can be glued together and are often sub assemblies of aluminium and other light weight materials bonded together. Just because you see a neutral bonding point (earth terminal) don’t assume this is is capable of being a suitable point to bond the neutral side of a circuit or accessory you are installing. Modern vehicles often have small bonding straps between sections that can carry the current that the vehicle manufacturer rated the bonding point for. Adding additional equipment and accessories might exceed the original design spec.
I did see a spectacular failure due to a 3000W inverter having it’s neutral lead ‘grounded’ in the rear of a vehicle. Running at about 2000W the neutral side was trying to ‘return’ a current of about 170 amps through the body of the vehicle, which lead to serious damage to some of the vehicles wiring and a number of vehicle components… and a ‘repair’ bill of nearly £1500.Putting a riv-nut in a body panel that is mastic bonded to the body is not a suitable negative bonding point!
Additionally a number of vehicle circuits are now negative switching or operation and installing additional equipment or accessories could have unforeseen issues. Always from any accessory or piece of equipment you install, add the neutral return path back to a suitable single common point or buss bar you install for the purpose and connect this directly back to the leisure battery.
Ideally all the ancillary leisure circuits should never rely on any of the vehicle wiring and the negative side of the leisure wiring should only ever connect to the negative side of the leisure battery.
Don’t use battery terminals as a junction post.
Both the leisure battery and engine battery should only have connections that lead to either in the case of the positive terminal a master fuse /circuit breaker and isolator switch. The negative terminal should only have the connection to a master negative terminal point or buss bar.
If you want to install any sort of battery monitoring, it is convention to install the shunt on the negative return to the battery between the negative buss bar and the negative battery terminal. If you have multiple circuits terminated on the battery terminal it makes future changes and upgrades, including installing a battery monitor very difficult.
Using the battery terminals as connection points for multiple services also makes fault finding very difficult. Each circuit may or may not have it’s own fuse and it’s difficult to isolate circuits….. plus I’ve had enough sparks flying round when trying to disconnect a battery because someone did not install an isolator to know that it’s only a matter of time before one goes ‘pop’.
Please, just don’t do it.
Have a think on this. If you had to go to an auto electrician to get a fault traced and corrected, they would immediately put at least an hours time on the invoice just to figure out what was going on with all the cables on the battery. Also, If you don’t have a battery master isolator installed, get one installed now. It’s a safety item that must not be missed out. Having the ability to quickly turn off all the leisure circuits in an emergency might just save you from the unthinkable happening.
Every cable should be terminated. Period. There shouldn’t be any cables in an installation that don’t have a crimped (or soldered) termination. Even if it’s a screw terminal such as those found in joining blocks or 13 pin plugs.
If you are embarking on a wiring project, its always best to start building up your stock of terminals. I usually buy selection boxes of terminals on line and supplement these with bags of single type connectors for the more commonly used ones. To keep everything organised tote organiser boxes are my preferred option.
There is nothing more annoying than running out of the something and its always just as you want to finish a project off so you end up cutting corners.
For some of the larger cables, if you don’t feel up to making your own terminations there is usually a local auto electrician available that will terminate them for you for a small charge. However, a crimping tool that will terminate up to 50mm cable is not that expensive – around £27 and will probably work out cheaper in the long run. I’ve a link to the one I bought via Amazon and regularly use in the SHOP page.
Get the size right…
Selecting the right size or gauge of cable is critical. There are two factors that determine what gauge of cable to use for a installing any particular circuit. The maximum current that’s going to be drawn and the length of the cable. Once you have selected the right size cable then means you can select the right size fuse for the circuit. Never fuse a circuit greater than the current capacity of the cable.
You can download these and other drawings from the Electrical Drawings page in the drop down menu under “Document Library”
I generally tend to list what is going to be installed, then work out all the gauge for the cables for the circuits. From there it’s easy to see which is going to be the most popular gauge and rather than buy several different gauges of cable try to select a limited selection of gauges.
Always go for the safe option of over specifying the gauge of cable for any particular circuit. If it’s a 10 amp circuit and you have used cable suitable for a 16 amp circuit, it doesn’t mean however you need to use a fuse greater than the 10 Amp circuit requires.
Something else to consider too. Most 12 volt cables are copper, however if you are installing them in a less than ideal environment, such as a boat, you may want to opt for tinned copper cables. These are far less susceptible to cable corrosion. Even in the best marine installations I’ve seen copper cables corrode through in less than a couple of years.
Cardinal Sin! – Never ever use two smaller cables to make up the equivalent of one larger capacity cable. You would be surprised how many times I’ve seen this… sometimes done by “professional” tow-bar installers when reported poor leisure battery charing or poor fridge performance is reported and the voltage drop is too great.
Wiring Looms – wrapping it up properly!
Dressing cables into looms is not difficult nowadays. There are many options available on the market to help you produce a professional looking finished product. I personally like for looms within the vehicle using a felt finished looming tape. You don’t wrap it so it overlaps but at a sharp enough angle so as it spirals round the cable bunch it leaves some of the cables exposed.
Felt is good as not only does it keep the loom together, it allows quite a bit of flexibility and prevents cables from rubbing or banging on flat surfaces making a noise.
For any cables outside the vehicle body there are two options depending on use. In the main I’d go for split tube conduit. It’s available in various sizes and can be bought in either cut lengths or rolls. The other option is to use self amalgamating tape. It looks like ordinary PVC tape but as you wrap it round you stretch it and it releases a chemical which when overlapped onto its self becomes a permanent bond, effectively making a sealed tube. It is generally however fairly inflexible. Both have their place.
Anything in the engine bay or underneath the vehicle I use split tube and generally only resort to self amalgamating tape to seal inline joints.
Relays….. yes or no?
For me its Yes. I much prefer locating all the relays in one place therefore minimising the amount of heavy cable. By using relays to do the heavy switching you can use smaller and sometimes more attractive switches. I have in the past used 7 core trailer cable to connect 4 switches including LED indicators back to a relay bank rather than make up a custom wrapped loom.
You can download these and other drawings from the Electrical Drawings page in the drop down menu under “Document Library”
It also makes tracing faults easier, as it’s simple to test if a switch is working, you can hear or sometimes feel the relay operating as you operate the switch. Its unusual to have a fault with a relay but quite simple to test… just unplug and swop over with a known working relay. If all the relays are located together it makes this task and testing the feed to the relays so much simpler. From that point all you need to check are the two wires going out to the device and the device itself.
Obviously some circuits don’t require a relay or if it’s designed to be turned on for a long period… such as a diesel heater, then adding a relay will just increase current draw, albeit small, on the leisure battery. A bit of common sense can easily determine if you should opt for a relay or not.
Grommet?…(no not Wallace’s friend!)
Whenever a cable or cables pass through anything solid you should use a grommet. You would be surprised at the amount of damage I’ve seen to cables due to either not installing a grommet to an insufficiently sized (too small usually) grommet.
When ever I pass either a cable or loom through a bulkhead for example I like to supplement a grommet with a bit of heat shrink sleeving over the cable as well. Even passing a cable through an existing grommet from the engine compartment to the interior, adding a length of heat shrink sleeve won’t do any harm.
Having a handy selection of grommets available before you start threading wires through is far better than trying to install protection afterwards. You’d also be surprised at how many cables I come across that have been damaged while pulling through holes in metal and wood panels. Always better to start with a grommet or two! Where a cable or loom passes through a grommet, it’s aways best practice to try and anchor the cable or loom either side of the grommet to something solid using “P” clips. This will reduce the chances of ‘fretting’ with the movement of the vehicle.
While we are on grommets…. a quick note about cable-ties (zip-ties). Stop doing them up so tight! I’ve come across cables cable-tied to a chassis rail so tight that the cable-tie has cut into the insulation and is fretting the conductor inside. Cable-ties are generally made out of a harder plastic than the cable insulation so will over time wear away at the insulation.
Get yourself a cable-tie tool that not only allows you to precisely control how much tension you put on the tie but also cut the end off so that there isn’t a wrist slashing booby trap lying in wait for some unsuspecting person. I use a fairly cheap pair (left). I think they were around £8. So not really expensive. But they make a nice neat job of installing multiple cable ties with the correct tension and the ends cut cleanly off level with the lock tab. You can buy ones that have a tension dial built in so you can set them to a pre-tension, but I find after a bit you know just how much to squeeze the handles to get the correct tension.
So what is the correct tension… well if you are doing them up so tight an elephant could dangle on the cables then that is too tight. They should be tight enough so as not to slip but you should be able to spin them round the cable(s).
Cable-ties really should not be used to make looms or anchor cables or looms to anything solid. If you want to make a loom, wrap it in specialist loom tape. If you want to anchor cable or a loom to something solid use a “P” clip. If required… use a length of heat shrink to make the loom a tighter fit in the ‘P’ clip.
I know you are dying to ask…. when do I use cable-ties? Well generally at the installation stage to get things to stay in place before installing P clips or if I have to run a new loom along the same path as an existing loom, I generally opt for cable-ties to hold them both together (as long as the original is suitably anchored to support both)
While we are talking abut cable-ties… I have seen the worst kind of mistakes in the use of them. It is not OK to cable-tie anything to brake lines, fuel lines, vacuum lines, hydraulic hoses, coolant hoses or steering components (yep one bright spark cable-tied his front LED light bar wires to some of the steering components!)
Heat Shrink Tubing
An absolute must have in my opinion. There are two main types – plain and pre glued. The plain are the main one you would use, while the pre glued are great if you have to over sleeve a connection to make it waterproof. As you heat up the pre-glued type, the glue softens as the tube strings and bonds to the cable as everything cools. They can be a little more rigid when installed, so make a service loop in the cable. The finished covering is usually waterproof enough for brief submersion if done correctly.
Having a selection of sizes and colours is handy and assortment boxes of multiple sizes and colours can be bought on line cheaply enough. In the workshop I use an old paint stripper heat gun on low power as I find that is more controllable than a flame.
Bridging the gap… something in the future?
Although not so common in the UK, in Australia and the USA wild camping (boon docking) is probably as popular as campsites. To this end trailers and caravans usually have much larger battery capacities than anything found in Europe. It’s not uncommon to find outfits with 600 to 800Ah battery banks recharged mainly be solar, buy increasingly (especially in Australia) an additional bridge between tow vehicle and trailer is made using heavy duty “Anderson” connectors and cables capable of supplying upwards of 60 Amps from the vehicle to the leisure battery bank.
With the cost of lithium batteries reducing almost daily, I can foresee very soon that light weight lithium batteries will be installed in caravans. The down side of this currently and trying to retrofit Lithium is the existing charging setup of current European vans is not really suitable for looking after these type of batteries. We have a Sterling Power Wildside unit installed in our caravan which allows us to charge any type of battery chemistry, including lithium when connected to the tow vehicle. The draw back is the caravan’s inbuilt charger is only capable of wet lead acid or AGM. I think that a high capacity DC to DC charger installed in the vehicle and an additional cable to supply the caravans battery banks may not be too far away. It’s something you might want to keep in mind for the future. It’s something I’m looking into currently.
Well, that’s a bit longer than I anticipated and there is still a few things to cover. If you made it this far…. take a toffee out of the jar… well done! If you think I missed something or would like me to cover something specific, drop me a comment below.
The problem with information on the internet is that although there is some great advice to be found there is also some less than great…. poor… really really poor advice and sorting out the good from the bad is sometimes not easy.
We are currently pitched on the Caravan & Motorhome club site Beechwood Grange near York and I decided to sit down and pen this post as for the last few months I seem to have been sorting out a number of problems via emails and phone conversations that really should not have arisen.
I’m going to give you a couple of examples of what’s been dropping in my inbox. To protect the inoccent I’m not going to name anyone or the channels. I do have the OK to relate these issues.
“Hope you can help, I’m converting a VW Transporter into a camper van and have been following a number of YouTube channels for information on how to do it. It’s nearly complete but I have a problem when I go to use my inverter off grid. The base of the seat starts to warm up and a get a funny smell in the front of the van”
After an exchange of emails and a few photos were sent I eventually worked out what was going on. The 2000W Pure Sine Wave inverter was floor mounted in a cupboard towards the rear of the van where it was convenient for the mains sockets on the inverter to be reached. A suitable size Positive (+ve) lead ran back to the two 100Ah AGM batteries located under the front seat. A suitably sized Negative (-ve) lead also ran back to the batteries and was bolted to the chassis under the seat along with a number of other smaller -ve leads. The batteries were mounted on a wooden platform above this connection. The +ve lead from the inverter went to one battery +ve terminal and a link wire to the second battery +ve tied the two together. The size and rating of this tie wire was a lot less than it should have been.
The -ve posts of each battery had a very short 10mm2 cable going to a threaded stud mounted on the base of the seat and were helpful on to the stud by a star washer and nut. The seat base was a 3rd party metal fabrication hat had been powder coated and bolted to the vehicle floor by 4 bolts and ‘penny’ washers.
What was going on?
When the inverter was operated, it drew current from the battery down the +ve lead. Apart from the fact there wasn’t a fuse between the battery and inverter this side of the circuit was OK. The return path however was a different story. The inverter -ve lead was connected to the vehicle chassis under the seat – not at one of the seat mounting points. The -ve of the two batteries was connected to a stud that was a press fit into the seat base. It didn’t have a hexagonal head just a mushroom head. It was also way under size for the terminals that were fastened to it. The oversize star washer stopped the nut pulling through the terminals. The return current path therefore had to flow into the vehicle chassis, up the four bolts holding the seat to the floor and through the seat base to the push fit stud and finally into the two short leads connecting the battery -ve terminals. The relative high current drawn by the inverter through the single undersized push fit stud and the four floor bolts that were securing a powder coated frame with penny washers presented enough resistance for 60 or 70 Amps of current to start to heat things up a bit and burning off some of the powder coating. 70 Amps passing through a 0.1 ohm resistance will generate 490 watts of heat (calculated using R x I2 = P) this is why it’s critical to get any cabling correctly crimped with the right terminals for the job.
Don’t rely on the vehicle chassis as a return path. install cables for both ‘legs’ of the circuit from source to destination and back again.
There wasn’t a fuse installed near the battery. Any cable coming from a battery MUST have a fuse close to the battery before it goes off anywhere to supply anything else.
If a cable terminal requires an M4 nut and bolt…. use an M4 bolt nothing smaller will do.
If you are ‘grounding’ to anything metal, clean the surface, use a dab of protective dielectric grease (there are different ones for steel and aluminium!) and make sure any washers used work correctly. Flat clean washers for electrical contact and a star washer as a mechanical anti vibration measure to stop the nut loosening.
“When ever we have been away for a few days off grid on the return trip there always seems to be a strange smell coming from the engine compartment. We have a self converted T6 camper and 400Ah of AGM leisure batteries with 240 watts of solar on the roof. After watching a couple of YouTube installations of DC to DC chargers I recently installed a Redarc DC to DC charger to help keep the leisure batteries in good condition and fix some issues I was having with the smart alternator”.
OK again after several email exchanges and a couple of video clips I got to the bottom of this one as well. The RedArc unit is capable of charing at 50 Amps and to do this pulls around 55 to 60 amps from the vehicles alternator. However there are a couple of issues in doing this. One of the first things that the Car Audio guys always recommend before installing any of the mahoosive bass pumping amps in vehicles is to replace and upgrade three essential cables. The first is the cable from the alternator output to the battery, the second which might not seem so obvious is the ‘earth strap’ as it is sometimes called from the engine to the vehicle chassis. This need either replacing completely with a larger cross section and also where it terminates on the vehicle needs altering. Usually the Audio boys install a new cable from the alternator mounting bolt directly back to the negative battery terminal*. Why” Well quite often the engine earth strap is just a simple copper braid strip sized just big enough so the starter motor current won’t burn it out for the 5 to 10 sends the starter is operated. You start trying to push the engine battery charing current and the additional 60 amps for the DC to DC charger through it, it starts to get warm. Not a problem as usually it’s not covered in a PVC jacket and hanging down in a bit of air flow under the engine. So the Audio guys change or upgrade it and they pull more current than we do. The third and last one that is upgraded is the short stubby battery negative lead going to the vehicle chassis. For our purposes, not really a necessity but hey ho.
*A note of caution. On most vehicles now there is a shunt between the large negative cable going to the battery and the negative terminal of the battery. This allows the vehicle ECU to determine the current flow in and out of the battery. It is important that you only connect any ancillary equipment to the cable side of this shunt and not to the battery side.However some DC to DC chargers specify you connect to the battery side of the shunt. Please refer back to the instructions with your particular unit.
What was going on?
Well basically the negative side of the circuit was getting a bit warm and the lead from the alternator was running at virtually it’s maximum rating. What you have to remember is that the vehicles electrical system is really designed down to a price and to do just the job of keeping the vehicle running. As soon as you start to ask a bit more of it you are stressing some elements and you have to consider all aspects and upgrade parts sometimes.
Adding an additional earth strap from the alternator mount directly to the chassis side of the shunt on the negative post of the engine battery and upgrading the alternator positive cable made a big difference and there is no longer any smell after a couple of hours of charging from the engine. Apparently starting the diesel engine has been improved with the report: “it seems to turn over a lot faster when starting” so maybe there was an underlying issue with engine earthing somewhere?
My two cent’s….
Don’t use the vehicle chassis as a neutral return path for any additional equipment you install. Modern vehicles are not so much welded as bonded together and some have aluminium or plastic body panels. Additionally even the steel they are made from is not as good a conductor of electricity as copper. Leave the vehicle electrics to the vehicle body and install your own neutrals.
Don’t ‘ground’ the leisure battery to the vehicle body. Keep the leisure battery circuits isolated from the vehicle body. Run a suitably sized neutral cable directly from the leisure battery to the vehicle battery.
Don’t use leisure battery terminals as a place to connect everything. Use a proper terminal bus bar block for live and neutral connections. The only connection on your battery terminal should be the main conductor going to either a second battery or a bus bar terminal block. The only exception to this is for battery monitors!
Don’t assume the vehicle electrics are up to the job. Most vehicle electrics do the job they were designed to do and not much more. As soon as you start asking the alternator to charge another one or two 100Ah batteries you are ‘stressing the system’ to a greater or lesser extent. Some big 4 x 4’s can handle this, some smaller vans might not be able to. Consider what you are installing and think about how the vehicle will handle this and look to see if anything needs upgrading.
Know what cable terminations to use and where. Also don’t cheap out on the correct terminal installation tool. If you are building or converting a camper van is it worth saving £25 on a proper ratchet crimp tool?
Don’t watch someone on YouTube do something and assume that if you do it exactly the same way it’s going to be right. It’s interesting on how many times people make a video on wiring or installing equipment and follow it up with “if you want to know more go and watch so and so’s video about it. He produces really good videos how to do this” Just because someone produces really good videos doesn’t mean the videos show how to do something correctly. It’s only how they did it, not an installation bible. You have to do your own research and learn to sort out the good guides from the bad.
I have watched an awful lot of YouTube motorhome refits, camper van, step van and bus conversions etc and a lot of the electrical installation – especially on the 12 volt side is poor in my opinion. I’m not an expert however and I’ll only ever say how I’d so something and the rational behind why I’d do it that way.
Just throwing this out there to see if there is any interest….. I was thinking about doing either a small forum on the blog or a Q & A page as a resource for some of the electrical ramblings. Would that be of interest/use to anyone? I do know that quite a few of the electrical drawings I have done have been downloaded and again wondered if specific drawings for equipment would be useful. Let me know in the comments below.
About 12 months ago I wrote a blog post “Is A Euro 6 Engine Killing Your Leisure Battery?” and it got a few comments and generated a number of emails. However 12 months on I’m getting a lot more questions relating to problems around smart alternators and I’ve brought forward this blog post by quite a few months from my planned posting date following a couple of long email exchanges with two readers and a few others.
Right, I think the best way to explain this is to set the stage so to speak.
Bob stores his brand new caravan at home and it is regularly plugged in to the house to run the internal battery charger and a dehumidifier. It’s got a new 110Ah AGM leisure battery and a new motor-mover fitted. The caravan is plugged in at least 24 hours before any trip to get the fridge down to temp prior to stocking it up. Bob also has a brand new car, Euro 6 diesel with a smart alternator. The car is a few months younger than the caravan and he’s never towed a caravan with this car. The tow bar and tow electrics were all fitted by the dealer (or dealers agents) prior to it being purchased. He did tow this caravan on 4 trips with his previous car, same make but 6 years older.
The caravan suitably prepped, fridge down to temperature and stocked. An early morning departure and six hour journey with a couple of stops to catch the Euro Shuttle over to France followed by a couple of hours driving in France to their first destination. On arriving, Bob sited the caravan on to the pitch not using the motor-mover and went about setting up. Mrs Bob knowing a request for a cup of tea was imminent went inside to put the kettle on where she discovered everything in the freezer had defrosted. Bob checked the fridge, it was still set for travelling. For what ever reason he also checked the leisure battery on the caravan’s system… 12.1 volts.
Over the next few days there was a couple of phone calls to their caravan dealer along with a number of emails. For the next three weeks and 2 other camp sites the fridge worked perfectly. On the return trip a similar distance and travelling time to the outward journey ended up when Bob returned home he only managed to get the caravan part way up the drive using the motor mover. He had to plug the caravan into his house overnight to charge the leisure battery enough to allow him to use the motor mover to finally put the caravan into its ‘home’ at the rear of the house.
Within a couple of weeks the caravan was returned to the dealer for extensive checking and the dealer could not find any issues with it or the fridge. They put forward the idea it must be an issue with the car. Bob tended to agree with this as he had taken this caravan on four trips towing with is old car and never had any issues. Three relatively short trips, the other a longer two week trip from the North East down to Cornwall, a similar 8 or 9 hour journey and everything seemed fine.
After a conversation with the main dealer who agreed to have the vehicle towing electrics checked over the next couple of days. The verdict from the main dealer was they could find nothing wrong with the vehicle, everything was working as expected.
Now, this is where I got involved. The above is actually an amalgamation of two very similar emails asking for thoughts and advice. The people involved had vehicles from different manufacturers and the caravans were also from different manufacturers. The only common element was the vehicles were new and had Euro 6 engines with smart alternators. I am not going to mention the vehicle or caravan manufacturers for a couple of reasons…. one, I don’t want to end up on the wrong end of a legal letter and two, I don’t actually think the manufacturer of either is relevant.
What’s Going On?
Luckily for me Bob is recently retired but knows his way round an AVO 8 being an apprentice TV repair man for Redifusion back in the day when valves were king. (Just as an aside, I bought my first AVO 8 back in 1976 and paid £8 for it. It was Ex REME in a leather case. I purchased it from MAZEL RADIO on London Rd in Manchester. Anyone from Manchester of a certain age will know Mazel Radio).
To cut a long story short over a period of a couple of weeks we proved that when hitched up, as soon as the smart alternator went into eco mode, there was a current flow up to about 4.5 to 5 amps FROM the leisure battery TO the car. This only stopped and reversed when the electrical load in the car caused the vehicles ECU to turn on the alternator’s output. Furthermore we determined that with the caravan hitched up, the period the alternator was in eco mode was also longer than when unhitched. Although we could not prove this with definitive evidence, this would also support the reverse current flow from the caravan to the vehicle that we were seeing as the caravan leisure battery was now supporting the vehicle battery.
Now there were a few questions that were buzzing round my brain….
Why didn’t the caravan habitation relay drop out when the smart alternator went into eco mode to stop this reverse flow?
Why didn’t the dedicated tow electrics strop this reverse flow?
Why didn’t the vehicle ECU knowing a trailer was hitched stop the alternator going into ECO mode?
If the ECU put the alternator into eco mode why didn’t it drop the fridge supply and by default release the habitation relay?
Why did the fridge defrost/not work even though in theory there was a voltage supplied to it?
Was this the reason I had seen an increase in emails relating to motor mover issues and batteries not holding their charge?
I don’t really know. I don’t know how wide spread an issue it is or its going to become. I also don’t know the details of how specific manufacturers implement eco modes in the ECU programming or how the tow bar electrical interface manufacturers could work round the potential issues while still being able to get their products certified by vehicle manufacturers.
I think it might be down to the caravan manufacturers to come up with a solution. I know that there are a couple of after-market products available that provide a solution – We have one I installed in our caravan and in the short term I think this will be the quickest route. Caravan manufacturers may have a reluctance to respond and they can legitimately say “Well it is designed to work correctly to the relevant standards.” I think that maybe it will require the two main caravan clubs to look further into this and if what I have outlined above is proven by them to be the case, bring pressure to bear on all the parties concerned to come up with a way forward to resolve the issue.
For my part, I have contacted a few manufacturers asking for information and clarification or even acknowledgement of an issue. Unfortunately no one seems to want to talk about it. I do know individuals have emails details of their own problem to manufacturers and have received less than helpful responses.
Let me know in the comments below if you have had anything that might be related to this. I’d like to find out more.
The thought just crossed my mind…. what affect, if any, will this have on AL-KO ATC (if fitted) when the vehicle is in eco mode and the alternator shut down? Does is mean that there is a possibility that the AK-KO ATC may not work correctly in all circumstances?
A short while ago two people contacted me separately asking if I had any information relating to rewiring restoration caravans so that they could plug into a modern 13 pin electrics tow car and take advantage of leisure battery charging and run a modern fridge or coolbox.
This was followed up be someone asking me how they could upgrade a late 1970’s caravan and still incorporate and use the “CAR-VAN” switch to change between using the leisure battery or vehicle battery.
I came up with a couple of drawings that covered the basics to show how they could be upgraded to modern tow vehicles. The one above is a basic ‘front end’ from 13 pin plug back to a fuse block for the road lights and a habitation relay.
The drawing below add in the option of a “CAR-VAN” switch (sometimes labeled as CAR-CARAVAN) which uses the same 40 Amp relay as the habitation relay rather than a chunky high amp switch found in some models. However installing a CAR-VAN switch does have limitations… for example you could not install an inverter.
If you want to download these drawings (or any others I have done recently) they are now in PDF format sized A3 and can all be found on the “Electrical Drawings” sub menu below “Document Library“. I kept getting emails asking where such and such a drawing was, so I decided to put them all into one place.
I don’t normally do electrical drawings for specific projects (unless being paid), however if you have something that you think might be of interest to a wider audience drop me an email.
I seem to have had an increase over the last few weeks of emails from people involved in building, modifying or upgrading Overland Expedition type vehicles. I think some of my posts must have been quoted or referenced in related forums. A lot of questions are related to roughly the same group of topics so I thought I’d produce three drawings to help answer the bulk of the questions. If you read down the comments on some posts I have answered a lot of specifics that might help. I’ve merged a lot of the questions into a paraphrased ones…
“How can I get my LED light bar and spotlights to come on when I use my main beam switch but I want to disable them when on the highway?”
The questions were from a number of 4 x 4 Off Road enthusiasts and Overland vehicle people. Simplest way I could come up with was using a couple of diodes (details on the drawing) Three switches… one for LED Light Bar, One for Driving Lights and one that allows you to sync the LED Light Bar and Driving Lights to the operation of the main beam in the vehicle. Flash the main beam and with the Sink Switch ON… all the lights will flash. Note… this may be illegal in some countries, so having the option to turn off the facility when on the roads ‘should’ keep you within the law…. don’t quote me on it!!!
“Whats the best layout for connecting a solar controller / inverter / isolation switch to my battery bank?”
The best schematic I could come up with that is flexible for most situations. I’ve put a few notes on the drawing. The various components I’ve drawn generically…. all can be found at your preferred supplier.
“What’s the basic layout of the vehicle fridge and leisure battery charing circuit?
This I think has come from a few on-line discussions relating to poor performance of the fridge and leisure battery charing in older 4 x 4 vehicles. I was receiving for a while a number of questions related to upgrading older installations. I also receive a number of emails asking how to add the facility of fridge and leisure battery charging to older vehicles and upgrade the 7 pin tow socket or old military lights socket.
You can download the PDF’s and are free to use for personal use. If you post them on other forums I’d appreciate a link back to this page and/or an acknowledgement.
I’d appreciate any feed back in the comments below.
A few weeks ago I posted a blog post called “A Quick Fault Finding Tip…” and that generated quite a few emails regarding electrical testing and how to trace faults. In fact a lot of the other electrical posts I’ve done over the years still generate emails and comments (it’s always worth checkingback on some of th eolder posts to read the comments) I’m going to try to explain a technique that’s really handy to have in your tool box for general fault-finding.
Earth Side Testing
Most people who perform general maintenance on their vehicle, motor home or caravan will be familiar with checking the voltage of the vehicle or leisure battery using a multimeter. Great little things to have and personally I think everyone should be able to do the basics with one. So as a bit of a refresher I’ll go through this scenario with you. Checking the lights on your tow vehicle you notice one of the brake lights is a lot dimmer than the other. Let’s find out why. I’m going to simplify the circuit a bit it should give you the idea behind the principle.
Depending on the device you re reading this on the drawings might be small. If you want to see the drawing full size just click on it to open it up full size.
In the drawing above you can see the basic circuit. The positive lead from the battery goes through the ignition switch and on to a fuse. From there through a connector to the brake pedal switch and on to another wiring loom connector to the back of the vehicle. It passes through another connector before arriving at the brake bulb holder. The holder is connected to the vehicle chassis via another wiring loom connector. The vehicle chassis is connected back to the battery in the engine bay. You can see we’ve checked the battery voltage with out meter and it reads 12.68 volts… so not a flat battery. We’ll make a note of the battery voltage.
OK… so the problem is this bulb is not at full brightness.. so it’s got to be a loss of voltage supplying it somewhere in the circuit. We need to check the voltage along the circuit with the bulb lit (circuit live) and the black negative lead of our multimeter attached the battery negative terminal. (I’ll explain how to do this later).
Probably the next place to check it would be the fuse… 12.66 volts, not too bad only 0.02 or 20 mV loss… lets keep going….
..next is a wiring loom connector, back probing it gives a 10 Mv drop (loss) normally these modern connectors are pretty good.
Brake light switch… Hmm a bit more of a drop… maybe a quick spritz with contact cleaner will sort that…
Back probing the next connector gives a bit more of a loss… I’ll come back and check the brake light switch connector.
OK, now at the back of the vehicle and a bit more of a drop at that connector but nothing too much…
Well 12.13 volts on the bulb contact… so between the battery and bulb positive tip a total loss of 0.55 V or 550 mV…. that’s about within limits as I would not expect to see much more than a 500 mV… half a volt drop on a typical circuit like that. So what’s going on? A 500 mV drop can’t account for the dim bulb?
However, if we keep going and measure the voltage on the earth side of the bulb holder….
Hang on we see a reading of 2.67 volts. How can that be? We are connected to ground at both ends of the meters test leads? A circuit has two sides, the positive side to the load – in this case the bulb and the return or negative side back to the battery.
Just because the negative wire on the bulb holder is only short and goes to a bolt securing it and maybe many others to the chassis doesn’t mean we can assume it is the same as being clamped to the negative battery terminal.
A few things to ponder…. vehicles are made of steel… steel is not as good conductor of electricity as copper… nether is aluminium that some vehicles have in their construction. At one time steel panels were all spot welded together… now a lot are bonded on with specialist adhesives. The earth point may well be in the boot or under the floor and will be subject to corrosion as will the main battery neutral cable in the engine bay. All this can compromise an electrical path back to the battery.
If we look at the voltage drop on both sides of the circuit we have 0.55 volts on the supply added to 2.67 volts on the neutral side…. 3.22 volts in total, so we are trying to light our bulb with only 9.46 volts.
Could we have got there quicker?
One of the checks I always do first with the ignition on is the battery voltage check to get a reference to work with and then simply move my red positive test lead over to some main point on the engine block….
If I get a reading of more than 0.4 volts (400 mV) obviously my negative return path from the vehicle chassis is compromised. Time to turn everything off and undo the main earth cables to the chassis and engine and give them and the mounting points a good clean with scotch bright or fine emery and a dab of specialist grease (see “Shopping” below) to protect them from further corrosion.
In the scenario we have just gone through, I’ll bet a wet weekend in Blackpool that cleaning both the earth terminal at the back of the vehicle and the battery earth to the chassis would have sorted the problem. I’d also have a look at the brake pedal switch as there is a bit more of a voltage drop than I’d like. Most likely it’s the connector rather than the switch itself.
For those that tow…
Nearly all tow bar wiring looms will ground to the same point in the back of the vehicle with some of the other assorted vehicle earth cables…. installers take the easy route and if there are already cables earthed there … then another couple won’t make a difference.
This can and will have an effect on the performance of your caravan electrics. Both the leisure battery charging circuit and fridge circuit will probably be earthed at that point.. So in the case of the fault above, each of those circuits will have a voltage drop of 2.67 volts. Therefore if you have leisure battery charing or fridge issues its possibly not the wiring in the caravan, it could be the wiring in the vehicle. Check the ground path first.
One quick check is with lights and ignition turned on, do a volt drop test between the battery negative terminal and one of the cable secured under the earth point at the rear of the vehicle where the tow pack electrics are terminated. If it’s above 0.5 V (500 mV) then give the earth points a clean.
One bit of advice I’ve given to people in the past is to run a 4mm or 6mm cable directly from the negative battery terminal to the back of the vehicle and terminate it at the earth point where all the rear lights and tow electrics terminate. Makes a heck of a difference.
Right…. Franky Howard fans stop it now! Back Probing, you might have heard of it and really it’s nothing special. It’s a simple technique used when fault-finding and involves using a fine probe to get into the back of the connector where the cable enters to test the voltage without disconnecting the connector. Sometimes you can get away with a straightened paperclip wound round the tip of the multimeter test lead. You can buy test lead accessory packs that have various attachments or ‘caps’ that fit on the end of your test leads to make the task easier.
How do I test between the battery and some other point on the vehicle or caravan?
I have made a few of these over the years… basically it’s a long length of wire, about 20 feet with a battery terminal sized crocodile clip at one end and a small crocodile clip at the other… and I don’t know how many I’ve given away to people. I have a couple, one long enough to get tot he back of the vehicle and one long enough to get to the back of the caravan when its hooked up to the vehicle. SImply clip one end to the battery negative terminal and the other to the negative lead on your multimeter. Often its an idea to tie a loose knot in the two leads to stop them coming apart. Caution though, this lead is connected to the ground side of the battery – don’t let it dangle where it might touch something… put a bit of tape for protection around the connection if required.
Multimeters…. a person can never have enough multimeters…. and since the demise of Maplin a couple of great places to keep an eye on is Aldi and Lidl. I got a couple of great general purpose multimeters from Aldi for £9 each. Not always available as they generally come up as special buy’s. However if you are an Amazon shopper then this https://amzn.to/2I91q91 seems like a great little multimeter with a lot of positive reviews for £12
I use Liqui Moli 3140 Battery Clamp Grease – https://amzn.to/2Vn0qSo for battery and chassis terminals. It’s a small tube but does last a while.
If you want to make your own long test lead this box of crocodile clipshttps://amzn.to/2VedU32 for about £4.50 is always handy.
A dream test tool…
If you are into testing or it’s part of your job then there has been something on the market for a while called “Power Probe” Now while the original is obscenely expensive and there are a number of copies out there. The Auto Power scan PS100 is priced at about £80 and does the job in one simple instrument – https://amzn.to/2OJHYAW (Any sponsors out there… hello….hello…) This is on my “I really want one of those” list!
As always when working on anything electrical think safety. Oscar our Health & Safety Cat would like to remind you that working on vehicle electrics can be just as dangerous as working on house electrics. If you are unsure then DON’T…. get in touch with someone who is qualified. Find the right person and they will usually help you to do it safely. Be like Oscar – Be Safe.
Following on from my last post – Never Admit to Being a Caravan Designer (Well Not to Caravaners!) I was floored by the number of emails I received on the subject of design. So after our trip out to the Manchester Caravan & Motorhome show at Event City a few days ago, I thought I’d sit down and pen a few more thoughts on the subject.
I believe that if you store something where you use it, it will make your life easier. One of the big items that almost every caravan wrestles with is the Aquarol. its bulky, fairly lightweight when empty, often wet from the liquid sunshine we enjoy in the UK and sometimes muddy. Where do you put it when travelling? OK, so you buy a bag to sort out the wet and muddy bit and maybe just put it in the doorway… or in the shower tray. That seems like a good place. Just carry it through your nice clean van and put it in the shower tray. Sorted…. unless you have a mid bathroom shower that has the shower ‘conveniently” located over a wheel so the floor has a step in it. The designers sell it as a feature… “You can rest your feet on it when showering” they say. However don’t stick your Aquarol in there if you have bi fold doors!
A fellow caravan enthusiast who shall be nameless – I’ll call him George… decided that this would be perfect for storing the Aquarol. He put it in the shower of his previous rear bathroom outfit for years without incident so no need to change anything. Upon arrival at site in with the first outing of the shiny new caravan all was going well until Mrs George popped her head out of the door and exclaimed to George that she could not get the Aquarol out. “It’s in the shower dear” exclaimed George. Irritatedly “I know that I can see it but I can get it out” came the rather louder reply. On examination of the problem George discovered that the carefully placed Aquarol had somehow shifted and was now preventing the bi-fold door from opening therefore stopping it’s extraction and subsequent deployment and use for brewing that much-needed cup of tea.
What’s the moral of this story? Well if you store something where you use it it will make your life easier. So as nearly all caravan users possess possibly one of the best inventions ever for transporting the splashy stuff about with ease why haven’t caravan designers thought about this? I was thinking of George when I was pondering the uses of this cupboard…..
There is a matching one on the other side funnily enough… but what did the designer have in mind for these cupboards… shoes (who would want to put wet shoes away in there?) Handbags…. maybe but I prefer to hang mine on a hook. It looks great… on a computer mock-up but as for use, well maybe I have a better idea. As they are right at the back of the caravan you really would not want to store your collection of beach pebbles in them.
Instead of a cupboard, just block it off and instead create a wet locker across the back of the caravan and stick a door like this in it……
… it may need a bit of adjusting size wise but imagine a wet locker accessed from the side that you use the Aquarol and wastehog on that you can simply throw these two bulky but relatively light items in… and there would be room for your wet and muddy mains cable too! All right where you need them.
Now here is an idea…. put the water inlet in there along with the mains inlet and a small hatch in the floor…. save on cutting holes in the side of the caravan and it means we all might just get away with using shorter mains cables!
Caution Vehicle Reversing
In a galaxy far far away… oops wrong blog…. I recently watched a chap valiantly trying to manoeuvre his caravan onto an awkward pitch using his motor mover. Stone walled raised bed one side, overhanging branches, awkward access angle all on a short pitch with a stone wall at the back of the pitch. Normally I’d postulate that the chap in question would have been able to perform this manoeuvre on a sunny afternoon with remote control in one hand, a mug of tea in the other while carrying on a conversation with the couple two pitches down. However at eight o’clock on a winters eve in near wartime blackout conditions required the use of a head torch (flashlight for my US readers) and a lantern held aloft by his partner and much wandering side to side and swivelling of the head to direct the head torch in the desired direction.
We don’t have a motor mover… for some reason Sue seems to take enjoyment from me sweating like a traction engine driver at a summer steam rally when reversing on to a pitch… but if we did, the question I’d have to ask is why don’t they have a 13 pin socket wired in so that you could simply plug-in the caravan’s road lights and turn on the reversing lights, hazard lights… heck even get the marker lights and brake lights to work. I’m sure there are people out there that have to detach their caravans on the road and reverse them into their drive and having simple flashing hazard lights and operational marker lights would be a good safety feature.
I have a small cunning device waiting to be fitted…. it consists of a remote key fob and a couple of solid state relays to be mounted in the caravan. On selecting reverse while seated in the vehicle I can simply push a button on the key fob and it will turn on the awning lights and can be made to turn on under floor LED flood lights to light up either side of the caravan. It stays on for a pre-determined time that can be adjusted so if you have to pull forward for a second attempt (highly likely) the lights stay on. Just waiting for a suitable time to mosey off down to the caravan storage site to do a test fit.
The Perfect Caravan
For those go you that have been following the blog for a while will know we have been flip-flopping like a stroppy teenager over getting a new caravan. Well we were…. then we weren’t than we were, then we changed our minds about what we wanted. Then we couldn’t find one and we changed our minds again… anyhoo we managed to tick more boxes off our list with one of these than any other…..
So the question is….. will we or won’t we? Will there be a deal at the NEC in February to tempt us…. or will we wait until the August price slashing begins?
By the way if you wanted to know how George managed to retrieve the Aquarol…. it required a wire coat hanger and a length of paracord…. and about four hours of fishing to raise the Aquarol up above the step in the shower tray.
Ok, not one of my usual blog posts. I get a lot of email asking about various electrical items related to caravans and motorhomes and a few things seem to keep cropping up on a regular basis. One is to do with 12 volt relays… what types are there and what are the pin connections.
Another is to do with cable size relating to load and its relation to the length of cable…. “I have a 40 Amp load and its 3 metres from the battery… what size cable do I need?” type questions.
In the past I’ve emailed back with answers, but one caravan engineer asked me if I know of any information sheets that had this type of info that he could put above his workbench.
So I’ve produced a couple of A3 size PDF information sheets (they will print A4) that can be downloaded printed out and pinned up, shoved in your notebook, glued to the lid of your tool box or used to wrap that must have tool present for your beloved caravan or motorhome DIY enthusiast in your life (seasonal eh!)
(I have been told that Office World can print and laminate A3 PDF’s cheaply…. I never knew that!)
I have stylised them as technical drawings and I’ve had to watermark them and some of the icons as I found a lot of my drawings were ending up “as is” or edited on various sites and forums without any credit or link back to Caravan Chronicles. You are free to print out and use them for your own personal use, but if you wish to use them (or any of my drawings) for commercial use, inclusion in blog posts or forums please include a credit line back to CaravanChronicles.com and drop me a line to let me know.
We are just back from Chester Fairoaks after doing the Chester Christmas market and a bit of shopping at Cheshire Oaks Designer Outlet Village and will be adding off to York for a bit more Christmas Market action.
I have a couple of more information ‘posters’ in development but if you have any ideas for future offerings, drop a line in the comments below. Of course my legal advisor – Henry has asked me to point out E & OE
(Everything on the internet is improved by a cat apparently… so here’s Henry)