Can I use old battery as a 2nd battery without split relay?

[mikeonb4c]

I've read a lot on BF about leisure batteries etc and hoping to install one as soon as I understand what I'm doing.

In the meantime, I have fitted a leisure battery tray and I have a spae 75AmpHr battery which was removed in favour of a new 95AmpHr battery (the old one went flat shortly after I bought the car so is probably not in tiptop condition - it worked fine after recharging though).

The question is this. Until I get a proper leisure battery, am I OK to put the old battery in the spare tray and connect it in parallel with the new one (i.e. black to black, red to red). I cant see it being a problem as long as the old battery is still more or less OK. I can disconnect it and use it to take power from (low amp duties only) so I dont draw on the starter battery. And it would allow me to commence the process of wiring up for the leisure battery and test that it works (installing new fuse box and rerouting car wiring to the leisure battery etc).

What do the the experts on BF think? Grateful for any tips / cautions. Off out to buy more bits for Bongoing now. The weekends have become fun again

[francophile1947]

Shouldn't be a problem Mike - just remember that, if the spare battery is not good, it may flatten your starter battery whilst parked, unless you disconnect it each time you stop.

[moonshine]

I agree with francophile1947. It would work ok as a temporary measure, but I would disconnect it each time you leave the vehicle in case it drained the main battery. You can get battery switches which will take starter current, and some of these fit on the battery terminal post. Fit one of those to save you having to use spanners to disconnect, remember to use starter cable to connect the batteries, and you will be fine.

[mikeonb4c]

Excellent franco and Moonshine and thanks as ever. I shall proceed in a forwards direction

[Barnet Al]

I see no reason why you shouldn't use the old battery as a leisure battery while its got some life in it but I reckon you are giving yourself a lot of trouble by not fitting the split charge relay at the outset.

Whatever way the batteries are connected you should use a high capacity cable and fit fuses to protect it. If you have to connect and disconnect it every time you start or stop the engine in order to stop it discharging the main battery, it will soon become a pain in the butt. Fitting a battery switch will help and probably be safer, but it will still mean lifting the bonnet every time. You've only got to forget it once and the van might not start.

Fitting a current sensing relay doesn't add that much to the job but observe warnings elsewhere on the forum.

[pyroman]

Hi sorry if this is slightly off the thread, but can anyone tell me where I can geta replacement croc clip for my jump lead?

Thanks

[francophile1947]

So, someone else is the proud owner of a set of broken jump leads!!!

[pyroman]

so what are we going to do?

mine is actually one of those booster/starter things so I don't want to just ditch it if I can hep it

[francophile1947]

That's a pity - mine were just those cr*p jump leads that that I bought years ago cos' it seemed a good idea at the time. You couldn't actually jump start with them, but they boosted your battery enough to start if connected to another car for a couple of minutes.
Unfortunately, I've just dumped one of those battery packs because the battery had packed up - charged for 4 hours and the lamp would last about 5-6 minutes. Mind you, when it was working, it would start a 2 litre petrol engine easily but not my 1.9 litre diesel.