Leisure battery drain ?

[Bison535]

My Leisure Battery drops its voltage slowly when parked up for a few days. Its a fairly new battery so is not suspect. Fridge is off and no known other devices running. Alternator has been fitted with a new Regulator.
What is the best method to search for and detect the battery drain fault ? Pull fuses ? Disconnect battery etc

Any help appreciated

T25 1.9 TD - 1990

[slowcoach]

Pulling fuses one by one is a good start. If you put a small bulb, like a rear light bulb, wired into the negative of the battery (between battery -ve and chassis) you can look for a glow, which will tell you if there's still a draw..

[Bison535]

Thanks for feedback Slowcoach,
Ref connecting a small wattage bulb between Negative battery terminal and chassis, should the main Earth battery cable be disconnected during the test ?
Therefore, If bulb glows then pulling fuses one by one the bulb would go out when the faulty circuit is interrupted by fuse pulling. Do I understand your method correctly ?

[AngeloEvs]

Does your Van have a Charge/switch unit such as the Zig CF8 fitted?

[Bison535]

Not sure about a Charge Switch ? But i do have the original battery charger unit under the bed seat ( Westfalia Type LG 20 black box) which I think does the Charging to both Engine and Service Batteries. It seems to work ok when on the road, 14 plus volts into the Service Battery and the set of LED Lights on the Sink Front show Service Battery charge ok.

[slowcoach]

Thanks for feedback Slowcoach,
Ref connecting a small wattage bulb between Negative battery terminal and chassis, should the main Earth battery cable be disconnected during the test ?
Therefore, If bulb glows then pulling fuses one by one the bulb would go out when the faulty circuit is interrupted by fuse pulling. Do I understand your method correctly ?

Yes exactly. I'd leave starter battery connected for the first tests, then if you dont find anything, go for the leisure batt. Some circuits may have been re routed to leisure battery though the main fuse box. You should find something. Any extra things installed? Aux lights, usb charger etc? Could be anything really, so don't rule anything out

[dunxd]

My leisure battery was draining out and it turned out the contacts for the water pump had got pushed together resulting in the pump operating the whole time (but since the tap valve was off, water wasn't flowing). I noticed on a quiet day when I could hear the hum of the pump - took me a while to track it down. Worth checking for things like this.

[Bison535]

Thanks guys for your responses. I am fitting isolating switches to both Starter and Leisure Batteries so when my camper is parked for a long period I can isolate them both. I know this does not cure any leakage fault, however, when this job is complete I will then revert to 'leakage testing' as per Slowcoach's idea; hopefully I can then define the real problem.
My van is a 1990 T25 built in Hanover, the previous owner had the original VDO Alarm system disconnected so there are stray/unused wiring in the electrical system plus a single hidden switch which immobilizes the starter system somehow !? No idea where all the wires go to or from, all looks a rats nest of wires
On the job, and thanks guys

[Bison535]

Now fitted a battery isolating switch to BOTH Engine and Leisure Batteries; so now when 'parked up' for several days both batteries retain their charge.
Water pump was not taking any current, but my 'tracker' was the only 'drain' I could find in terms of a 'parasitic battery drain'
Will fit a small solar panel to 'tickle' the battery whilst parked up.
The two isolating switches will also act as an anti theft device

Thanks for your feed back guys, cheers for now and Happy Camping

1990 T25 - 1.9 AAX TD

[Mocki]

you need to wire your tracker so the isolator switch does not cut power to it , or it will be useless should you need it when the switches are off !!

[937carrera]

I would keep it simple.

Leave the van a day, disconnect the battery, check voltage with a multimeter.

Check it again a few days later, the longer the better.

If the voltage has dropped then one of the cells has a fault on it.

[Bison535]

Thanks guys, good points noted

[Tinium]

you need to wire your tracker so the isolator switch does not cut power to it , or it will be useless should you need it when the switches are off !!

May be worth checking the power drain of any tracker too - The TK103 family that are popular on eBay draw about 0.07A, which is just under 2AH a day, which will draw a 90AH leisure battery down surprisingly quickly, say if you don't drive the van for a couple of weeks... dash solar panel may help offset it

(PS - Not an electrician or mathematician, so hopefully I'm not barking up the wrong tree here, just what I've seen with my van)