Currently EHU Only - can I run off 13 pin lead?
Hi All,
Quick question, can I use the existing 13-pin tow lead to power my caravan from a leisure battery?
Recently I installed motor-movers on my 2014 German Caravan and after discovering it had no on-board leisure battery, I purchased a dedicated 100Ah GEL battery and EXIDE 12/15 charger.
Presently the caravan functions on 12V (interior lights/water-pump/fridge etc) when the 13-pin tow lead is connected to a tow-car.
So theoretically if I wired another 13 pin plug socket connected to the leisure battery terminals I could at least power the Water-pump and LED lights without electric hook-up?
Presumably I could also install a master switch-panel between the leisure battery and the 13 pin socket in order to turn on/off the exterior LEDs - like the side lights, reverse, indicators, tail and fog lights to help with evening BBQs (even when I am hooked up)
Thanks very much reading and appreciate any help
Todd
Comments
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Yes, you can. I’m dashing out now but will reply to you more fully in a while.
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Great stuff, also I plan to use an old ZiG CP400 to turn on/off the desired output and I'll run the fridge on gas when not on EHU !
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Here we go then. I'm not familiar with your van, e2, but generally the answer is, yes, any 12v system that works when connected to the car with the engine off should work if your battery is correctly connected to the socket via a suitable fuse and cable.
Marker lights etc should work if the battery is connected to the pins that feed them via a suitable fuse and switch but some led marker lights may not work.
If your fridge is mains or gas only the following will not be relevant but, if it is a compressor fridge with a 12v option, it should work with the engine off but may soon flatten the battery. However, an absorption fridge normally only works on 12v when the engine is running but requires a permanent 12v supply to the control panel to enable it to work from any power source.
I can't say whether your charger is suitable for the purpose intended.
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If you have already installed a leisure battery in the van I am not sure why you want to connect it via a 13 pin socket? Of course, you can do that but it would be better to have the internal van 12 volt systems run from your leisure battery then when you are connected to the tow car you use that supply and when the engine is running you power the fridge and charge the battery through the ignition relay in the car. Rather than trying to wire the van external lights through the pins on the 13 amp socket it would be better to wire in the battery as suggested and have an external light if some kind off of a dc socket.
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Presently the caravan functions on 12V (interior lights/water-pump/fridge etc) when the 13-pin tow lead is connected to a tow-car.
I'm a tad confused.
Dont German caravans have habitation relays?
UK caraan's wouldnt allow any function other than fridge and battery charging when connected to a car.
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My toilet flush didn’t work when connected to the car.
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Thanks again for all your comments.
My question was really around whether the standard 2.5mm copper power wire (in the tow lead) was suitable/safe to use continuously for 12V LED lighting, truma water heater, 12v fan for warm air circulation and occasional water pump/toilet flushing.
I'm really not too sure why all the 12V systems function when connected to tow car but I know there's a factory-fitted "Dometic 400W converter/switching power supply" hidden beneath the wardrobe floor (with other no fuses/gauges/controls visible).
In terms of wiring the leisure battery directly to the vans existing circuitry, its a possibility but I would need to explore further whether this 4K factory option is achievable without too much expense
I just thought it would be possible to simply install another 13 pin supplementary socket on the A frame connected to the leisure battery that the caravan 13 pin plug can be inserted to supply the 12v circuits whenever the car is uncoupled, Perhaps later I can modify it to include relays which automatically switches the 12 v from the car supply wire to the caravan battery instead of using the supplementary socket when uncoupled.
Sorry for the long posts but really thought others may have already done this on there German made caravans ?
Cheers, Todd
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If it all works when coupled to the car, then why not to a battery?
My thoughts are,
Voltage drop, that is when the battery discharges could this damage either wiring or components.
What would happen if the battery and EHU were used simultaneously, is there danger again to components or wiring.
Charging a battery can and does cause gases, your precautions within a caravan environment ?
Presumably when attached to the car the engine is running, so voltage high and constant, and no mains connections.
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Being able to leave the heating on whilst towing would be handy on our caravan considering slow heat up times for the Alde
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I can't imagine any battery, lithium or not, that would have sufficient grunt to run a water heater.
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I was thinking power to the gas circuit.
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Thanks, I will continue with my plan to "fool the caravan" into thinking its still attached to the tow car for 12V electrics
Found out today that it has in fact a Truma APS 400-K which in the instruction manual states ...
"In mains operation all 12v outputs are supplied with filtered and stabilized DC voltage. If the mains supply fails, the device switches automatically to the vehicle battery for the power supply. To do this, the battery must be connected to the battery of the towing vehicle."
And yes my Truma water heater (Model BN 10) requires the 12 V electrical system for gas ignition, control and surveillance (via electronic control).
Cheers again - Todd
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Re: Charging a battery can and does cause gases, your precautions within a caravan environment ?
Yes I was really hesitant about putting a battery in the living/sleeping space, so I bought a separate sealed compartment that is bolted to the floor of the front storage locker (outside the caravan).
As a precaution, I also bought an EXIDE sealed GEL battery and matching spark-proof charger which has a built-in temperature compensator that adjusts the charge power depending on the surrounding temperature and prevents overheating. I know its over kill but the risks weren't worth it, especially for the sake of installing a couple of motor movers!
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Motorhomes nowadays have sealed batteries inside the habitation area although they are usually placed in a lidded battery box (plastic) with a vent to the outside. There is a small possibility of discharging Hydrogen if the charger fails and overcharges the battery although I am not sure that the box/venting system would be very effective for a serious failure.
The charging system should limit the charging voltage to around 14.4 volts which is below the gassing level for a lead acid battery. Obviously it is important to have the correct charger or correct setting for a sealed battery.
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Is the battery next to gas bottles ?
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Technically yes but its secured in separate sealed battery compartment approx. 2 metres away from the gas bottles, which both have brand-new (2018) pigtails.
The main reason I chose the front locker position is that its well ventilated (no drilling) and its central location mean the motor mover cables could be of equal length.
And now I can attach a 13 pin socket in the A frame, so the caravan lead can easily plug into for occasional non-ELU.
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