How to charge caravan battery whilst towing ?

Ian341 · Mar 2, 2008

Hi All

Probably a bit of an easy question but I have just had the white socket fitted to my towcar and tried it out for the first time today, I put the rocker switch inside the van onto car, however, even with the engine running the level of the battery didn't move from red. I then switched it to caravan to find the battery level at the top of green.

What position should I put this switch on (van, off , car)

I switched the red button on the fridge on and the light came on. Am i doing this correct ?

Many Thanks

Ian

Tankie · Mar 2, 2008

Hi Ian

See my reply in "Fridge change over switch" on this subject. Basicaly according to my Swift Owners Handbook, if the plugs are wired up correctly, then when towing, the rocker switch should be in the "central" position, then when the engine is runnig there is power going to the fridge, so long as that is switched to battery operation & there is also power going to charge the van battery. I have a 2004 Swift and the instruction applies to all models, certainly those built in 2004.

I have always done it this way and never had a problem!

Tankie

Ian341 · Mar 2, 2008

Hi,

Today I wanted to try to see if I could power the vans lights whilst connected to the car.

I connected the grey socket, started the car engine. I then turned the caravan switch to "car" and turned on the 12v halogen ceiling light, nothing, I then switched it to "caravan" the level went upto green and the light came on.

Was the battery still being charged whilst the switch was on caravan or does it only charge in "on" or "car" if so how can I charge the battery off the car and run the interior lights ?

The van is a 2000 challenger incase this helps.

Many Thanks

Ian

rayc · Mar 2, 2008

Ian, the answer is it all depends upon the modle of control Unit you have fitted!

On my 2006 Ace Award the switch works like this:

Van position: The van battery will feed the 12v electrics and be charged from the battery charger whilst on EHU. In this position the van battery willbe charged from the car en route.

Centre position: The van battery is disconnected and the 12v electrics will run only from the charger whilst on EHU. The battery will not charge from the car whilst en route.#

Car position: the van 12v electrics are fed from the car supply on pin 4 of the 12S. The van battery will not charge in this position.

Your info "I connected the grey socket, started the car engine. I then turned the caravan switch to "car" and turned on the 12v halogen ceiling light, nothing, I then switched it to "caravan" the level went upto green and the light came on".

This a bit confusing as with switch in the van position the 12v lights etc. should be isolated when the car engine is running. There is a "habitation" relay in the van which is switched by the fridge supply on the 12S. When the relay operates the van 12v circuits should be isolated from the van battery and the supply on pin 4 of the 12S fed to the van battery to charge it.

What make and model of control unit do you have?

Tankie · Mar 3, 2008

Beats me why they keep changing the systems.

There cant be a lot of difference between charging the van battery through pin 4 & running the fridge, through pin 6, when the engine is running and the switch on the ESM4 is in the central position as it is on my 2004 Charisma.

What I cant understand is why Ian wants to run lights in the van, when the engine is running,as usually, when engine is running the outfit is moving. If its just a flat battery he is trying to overcome, on site and there is no EHU or generators available, personally I would remove the battery, SECURE it in the back of the car, connect it to the 12s and go for a run for an hour or so.

This may be inconvienent, but it would avoid exhaust gasses getting into the van zzzzzzzzzzzzzzzzzz!

Tankie

Ian341 · Mar 3, 2008

Hi both thanks for your advice,

Basically what I am trying to achieve is that if we are on site without hook up and the wife is half way through her shower can I simply connect the car and leave the van on "van" as if I put it on car this would cut the power for the interior therefore cutting out the water pump.

The unit is a plug in systems not sure of the model number though sorry and unable to find it till next week as the van is in the dealers having warranty work done. It is 2000 Challenger if this helps.

I think the way it should be done is 1) Switch on car when towing and 2) switch should stay on "van" when on site and in need of charge.

Am i correct ?

Your replies are greatly appreciated !!

Many Thanks

Ian

Tankie · Mar 3, 2008

When switched to "CAR" all 12v circuits in the van should work! so there should be no interuption to the pump, I'm assuming the water is being heated by Gas!

Ian341 · Mar 3, 2008

thanks for the reply, we heat the water on gas when no ehu and also the fridge and heating work on gas, the tv and lights run off battery.

I have tried working the interior on "car" and nothing happens when i switch to "van" the lights come on. Is this something that should be checked with the van still in the dealers ??

Many Thanks

Ian

rayc · Mar 3, 2008

ian in reply to your question " have tried working the interior on "car" and nothing happens, when I switch to "van" the lights come on". There is something wrong. I am saying that on the assumption a)The car is connected to the caravan via the 12S. b)the car engine is not running.

To sum up:

With the car connected to the caravan via the 12S, and the engine NOT running, you should be able to switch between car and van positions and internal 12v electrics should work in both positions. Does this happen? I assunme not from your last post - it only works on the van position?

If you then start the engine the internal electrics should not work in either position. The fridge should get the supply from the car and the van battery should charge from the car.

Please confirm: Have you got 12 (+ve) on pin 4 of the 12S with (-ve) on pin 3? It should be there no matter whether the car engine is running or not.

With the switch set to van and the van internal lights switched on start the car engine. Do the lights go out?

Ian341 · Mar 3, 2008

Hi Ray

Unfortunately i have not had a good chance to have a look at the socket therefore can't answer your first question.

When the switch is on "van" and the engine is off the lights are very dim and barely on, I then start the engine and the lights go bright.

When I turned the fridge on battery the light didn't come on then after about 20 seconds it came on. I don't think the white socket has been used very much as we have not used it and we are unsure for how long the van was at the dealers.

Many Thanks

Ian

rayc · Mar 3, 2008

Ian

"When the switch is on "van" and the engine is off the lights are very dim and barely on"

This indicates to me that the van battery requires charging.

"I then start the engine and the lights go bright".

This indicates to me that at this stage the car is not providing the fridge supply on pin 6(+) and pin 7 (-)i.e. the car relay has not yet operated and therefore the car supply on pins 4 (+) and pin 3 (-) are feeding the van 12v. This is not ideal but is not a problem as such[see my next comment].

"When I turned the fridge on battery the light didn't come on then after about 20 seconds it came on".

This indicates to me that the car relay operated after 20 seconds thus feeding the fridge and in addition operating the "van habitation relay" which should have switched of the van lights and fed the supply on pin 4(+) & pin 3 (-) to charge the van battery. It is fairly normal for the relay to lag in operation at engine tickover as it is voltage sensing. If the engine had been revved it would have propably operated straight away if not it requires adjusting.

Are you happy with the way it should work now?

Ray

Ian341 · Mar 4, 2008

Hi Ray

Thanks for your help on this it is greatly appreciated.

The van has been in storage for about 5 weeks with the battery onboard so it was probably flat.

The fridge light reamained on for the 30 mins it took to get the van to the dealers so the delay must have been what you explained.

Thanks again for your great help !

Ian

rayc · Mar 4, 2008

Ian, if you have any further problems ask the moderator to allow you to send a message to me on my email address- it will be much easier by email than the forum. Ray

chenzhen · May 19, 2016

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