200 Tdi battery discharging?

[renault4]

780 amp battery, 18 months old, no previous problems. sunday morning, nice and warm, flat battery.jump leads, no probs, car used all day. next day, flat battery.

battery charged with charger overnight.next morning, OK, after work OK, next morning, flat battery.Then discovered when reconnecting poss. lead onto battery, a small

arc, suggesting a flow of current, so, all fuses out but still a small arc. after another re-charge, all OK and still OK when left with battery poss. lead disconected untill needed.

so my thoughts are that the battery is discharging through something not on the fused side of things, but what can it be?

what checks can I make to isolate and solve this problem?

[western]

try changing the start relay behind the fusebox metal panel [it has white/red trace wires & brown wires to it's mounting block] it could be the relay is stuck in the powered position.

[roohairy]

I have a similar issue with a 300TDI discovery, the battery discharges overnight to 11.7 volts then stabilises. Bought a new battery, does the same. Tried a 3rd battery from another vehicle, does the same. It will not discharge below 11.7 volts, even over several weeks, and the batteries are fine if disconnected. In a flash of inspiration I thought it might be the alarm siren battery that is bad, dragging the main battery down so have isolated that, the problem continues. Anyone got any ideas where to go next, will be looking at the starter relay.

BTW 11.7V is enough to start it most of teh time, only have problems on frosty winter days! Thanks,

[crwoody]

How about a leaky diode pack in the alternator?

Try loosening the connector for the thick brown wire on the alternator and give it a wiggle on the stud so see if you get any sparks, be careful not to short anything out while loosening it though.