Hi,

740 230FT with Bosch ignition system. Battery loses charge overnight and engine will not start. Starter turns over but not enough charge to get the engine running. When battery is charged fresh from battery charger it starts well. The battery is 2-3 years old and has been rarley used over the last year. This battery drain problem was first diagnosed about 18 months ago and since then the car has been rarley used.

I have looked through the forum and I have got a lot of tips and tried things but I still can't get the battery to hold charge over night.

I have cleaned battery and engine block connections +ve and -ve.

It feels like I have a drain of power with something left turned on or a short circuit.

I tested for drain with engine not running and pulling fuses. I got a 0.15 drain on fuse 5 the instrument panel and clock. And a similar drain on fuse 1 the fuel pump.

Are these drains normal? I figure the clock must use something.

The alternator and battery test have both tested good when running. The alternator is sending good power to the battery. (Of course the battery reads low voltage when it is drained.)

I have seen that there are sensors and relays that can cause a no start. The fuel pressure regulator, fuel pump relay, power stage amplifier, fuel injection relay, radio noise suppression relay, RPM sensor.

But my 740 starts right up with a fully charged battery.

Could it be the battery not holding charge? I have avoided buying a new battery so far. Is there a way I can test if the battery holds charge?

I have looked at all the small lamps in the trunk, under hood and they all seem to be off and not draining when the car is inactive.

Help appreciated!

Thanks,

Dean