Trickle charge caravan battery in boot

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Mon 28 May 2007 15:39
Trickle charge caravan battery in boot - J1mbo
Hi all, I have a 75Amp caravan battery in the boot of my 05 Mazda6. I'd like to trickle charge it to keep it topped up. I have a mains charger to give it a full charge overnight.

Its been suggest I could simply take a fused supply from the cigar socket straight to the battery. The cigar socket is only live when the ACC is on using the key.

Otherwise any other suggestions? I don't want to fry the modern electrics and worried about CAMs and Buses and things.

Jim
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Mon 28 May 2007 15:59
Trickle charge caravan battery in boot - Screwloose
J1mbo

Forget the cigar lighter socket - not man enough - it simply hasn't the fuse or wiring capacity to pass a charging current. [Nor does anything else in the standard wiring.]

If you have a 13-pin [or dual 7-pin] towbar wiring set-up; then there should be provision for a split-charging feed [in the 7-S socket.]

If not; you'll need a proprietory split-charge relay [a voltage-sensing one is best] and it'll need wiring-in, following the instructions carefully and using the specified heavy cable. Generally; the bigger the cable - the faster the charge.
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Mon 28 May 2007 16:55
Trickle charge caravan battery in boot - David Horn
J1mbo, I honestly wouldn't bother. A lead acid battery has a self discharge rate of 1% to 5% per month, which means you can leave it in your boot and simply whack it on the mains charger every six months. Even with a "worst case" discharge of 5% per month, it will still be about 70% charged after 6 months.
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Mon 28 May 2007 17:51
Trickle charge caravan battery in boot - milkyjoe
j1mbo, did you mean to charge the battery whilst touring so you can use it on a daily basis in between pitches as it were?
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Tue 29 May 2007 11:29
Trickle charge caravan battery in boot - Cliff Pope
j1mbo did you mean to charge the battery whilst touring so you can use it
on a daily basis in between pitches as it were?


That's what I do. I have wired in an optional second battery near to the main battery, with heavy duty cable and a cut-out switch. That way I could drain the caravan battery overnight, secure in knowing I could still start the car, and then charge up the second battery at normal alternator output.
But you can only get out what you put in. Trickle charging a spare battery isn't going to recharge it from half-flat overnight. And if it did, you would have half-flattened the car battery in doing so.
What do you want to do - trickle charge a basically unused battery in order to keep it always 100% charged, or recharge a battery that has serious use on a daily basis?
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