# Using leisure battery to charge flat engine battery



## greywizard (Dec 3, 2010)

hi all,
i have just fitted a cigar lighter wired to the liesure battery and had the thought that if my engine battery was flat i could use one of those cigar lighter to cigar lighter chargers to boost the battery(the van cigar lighter is permanently live).
is there any reason i could not do this ?
cheers


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## kandsservices (Sep 5, 2010)

It should work as long as they are both permenent live.Might take a bit of time through to charge a flat battery from a leisure battery.
Kev


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## andrewball1000 (Oct 16, 2009)

Friend of mine ran his starter battery down using the radio too much while parked up fishing for a week in Spain. He plugged in a Halfords trickle charger to the inverter off the leisure battery and was able to start OK after it had put enough in. I understand that "Bootstrapping" in pc terms means "lifting yourself up by your boot laces" sound similar.
Andrew


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## RhinoInstalls (May 11, 2010)

If the leisure battery is on charge that should be OK, if they would level each other out so you could have 2 half flat batteries.

Phil


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## geordie01 (Apr 20, 2006)

or two half full batteries


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## thedriver (Feb 14, 2011)

Hi, if you are parked up for a while with no hook-up,as long as your batterys are not far from each other,run a piece of a fairly sturdy wire with small crocodile clips from the + post of your leisure bat to the + post on your starter bat,but it only works if you have solar panel,iwill trickle charge both !! works to keep leisure topped up over the winter as well 


Bruce (the driver)


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## thedriver (Feb 14, 2011)

HI, PS don't forget to take it off before you start the engine,cos the power from alternator could burn the wire out!!


Bruce.


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## Hymervanman (Aug 20, 2010)

On my works van, which is 24v, I was once caught out with the two main vehicle batteries going flat. I used a set of jump leads from two leisure batteries which I have for inverter/lighting etc and "jumped" the main vehicle batteries- this got me started and then I could sort out the underlying problem of why they were flat later.


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## SpeedyDux (Jul 13, 2007)

Hi greywizard,

I have used one of those cigar lighter to cigar lighter contraptions to allow the leisure battery to put enough charge into a flat vehicle battery to start the engine. It took about 20 minutes.

The missing link was a 12 volt Hella DIN socket to cigar lighter adapter that I got from Towsure:

http://www.towsure.com/product/Cigar_Plug_into_Hella_12v_Socket_Adaptor

SD


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## Jezport (Jun 19, 2008)

thedriver said:


> HI, iF YOU ARE PARKED UP FOR A WHILE WITH NO HOOK-UP,AS LONG AS YOUR BATTERYS ARE NOT FAR FROM EACH OTHER,RUN A PIECE OF A FAIRLY STURDY WIRE WITH SMALL CROCODILE CLIPS FROM THE + POST OF YOUR LEISURE BAT TO THE + POST ON YOUR STARTER BAT,BUT IT ONLY WORKS IF YOU HAVE SOLAR PANEL,IWILL TRICKLE CHARGE BOTH !! WORKS TO KEEP LEISURE TOPPED UP OVER THE WINTER AS WELL
> 
> bRUCE (THE DRIVER)


If your leisure battery has recently been on charge there may be hydrogen around from gassing, using a croc clip can make a spark and cause an explosion!


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## TR5 (Jun 6, 2007)

If this is an ongoing problem, the best solution is to fit battery master, and automatically transfer charge to the vehicle battery when needed.


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## thedriver (Feb 14, 2011)

Hi All,
This is getting complicated,I did mean use the crock clips when there is no fault on the van.the amount of current going through a smallish bit of wire should not cause a spark. NOW if you use jump leads or a starter pack thats a different story. You are right though,any spark of any kind should be avoided where an ECU is present,which is most vehicles these days!

Bruce


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## thedriver (Feb 14, 2011)

Good thing Smart chargers but a bit of wire don't cost £100+

Bruce


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## greywizard (Dec 3, 2010)

*charging from liesure battery*

hi all,
thanks for all the replies---very helpful.
it looks like it would be o k to do it in an emergency.

cheers


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## jhelm (Feb 9, 2008)

I was just thinking I should mention that I've been doing this for a while now. Since my Electroblok got a bit messed up I'm using a regular battery charger wired into it to charge the habitation batteries but it doesn't do the engine battery. So I just did a wire with cigar plugs on each end one into a socket in the camper and one into the dash lighter socket. It's a bit slow but seems to work just fine.


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## Sprinta (Sep 15, 2010)

geordie01 said:


> or two half full batteries


or 1 half flat and the other half full :lol:

and when they go half flat, are they flat on the top or at the bottom like a tyre :lol: :lol:


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