flat battery??

[bongo-mick-sue]

hi, i wonderered if anyone can help. i used my leisure battery to power the fridge overnight, and it was flat in the morning. i thought no prob, ill just charge it up with the engine. but it wont charge. the engine battery is fine but the other one is completly dead. i have a zig unit, and i have checked the trip switches, they were still up. i found a fuse on the zig unit and that looks ok too. if it has blown a fuse in the fuse box, how do i know which one it is?. any help or suggestions would be appreciated, thanks
mick and sue

[trevd01]

What sort of fridge? Unless it is a compressor fridge (Waeco or Indel are the most popular in Bongos), I'm not surprised that the battery is flat.

If it is a compressor fridge - we get about four days and nights running our Indel on an 85 a/h leisure battery - you have a problem.

[Vanmanerik]

I think if you totally discharge a battery you can destroy it.

The fridge should have a gizmo that turned the power off if the battery voltage fell to a critical point.

Quote from a website http://www.virtualtechnologiesltd.com/F ... %20FAQ.htm

Excessive discharging a battery can also damage a battery. The amount of discharge a battery can have without damage depends upon the chemistry of the battery, but in general a lead acid battery will not tolorate as deep a discharge as a Ni-cad battery or Ni-mh battery. Sealed lead acid batteries function best if they are discharged to only about 85% of nominal voltage (10.2V on 12V battery).

They can be saved by I think it is called 'Pulse Charging' but it is a specialist bit of kit.

Hopefully some-one with a better knowledge of batteries will see this post and advise.

[pippin]

I suspect that the totally flat battery was too much for the charging circuit when you started the engine.

Look for a fuse somewhere coming from the positive terminal of your leisure battery.

You can tell if blade fuses have blown simply by looking at the edge.
The loop of fuse metal will be obviously melted if it has blown.

[bongo-mick-sue]

thanks for all the replies, especially pippin. thing is i did find a fuse coming from the positive, but it seems ok, so it must be a fuse on the fuse board. but how do i find out which one is what puzzles me. i suppose ill have to pull all of them out and check them all.
thanks again....any other suggestions?
mick and sue

[moonshine]

Is the split-charge relay definitely pulling in? Can you hear it click? Try putting a multi-meter across the leisure battery terminals with the engine running. This will at least tell you if charge is reaching it.

[harpo42]

Was it all working ok before?
Depending on what sort of relay/charging system you had this may be at fault. I originally fitted a towsure current senseing relay however the relay itself is not up to the high current needed to re charge a completely flat batttery. As pippin said may have blown the fuse however the it could have destroyed the relay unit itself.

[Simon Jones]

If you have a compressor fridge, the instructions for the Zig CF8 say you should not connect the fridge to the fused output of the unit, but connect it to the input from the leisure battery as the load drawn is too much for the unit. I had the opposite problem this weekend: even with the fridge, etc running of the leisure battery, I still managed to get a flat main battery. Thanks to Tim for the jump start at Lymington.

Other things to check on the Zig unit: when on hookup, have you go the the orange mains switch on & the next switch set to "on site"? When driving, this switch should be changed to the "touring" position so it charges the leisure battery from the alternator.