Land Rover Repair: 94 Discovery - Battery Drain, mechanic friend, battery drain

Question
Hi John,

We have a 1994 LR Discovery that is having problems on startup which we believe may be due to a battery drain.

Upon trying to start the car it repeatedly clicks when we turn the key but doesn't start. Once connected via jumper leads it starts without a problem.

A mechanic friend has tested the alternator, battery and starter motor and believe all to be fine, with a good level of charge being generated.

We think the drain (if it is a drain) may be caused by the air conditioning, which when driving, cuts in and out and when turned on causes the stereo to shutdown and the gauges to perform erratically.

Any thoughts on possible problem and our suggestion of battery drain?

Thanks John
Sam

Answer
The air conditioner is not a likely source of battery drain.  The best way to find a drain is usually to park the truck, then connect an ammeter in circuit with the battery and then pull fuses one at a time till you find the source.  A normal drain on that truck is perhaps 0.02 amp. You probably have 1 amp or more if it goes dead quickly, and that should be easy to find.  Disconnect circuits till you identify the one with the drain, then get the wiring diagram and follow that particular circuit.  

Remember that the alternator itself may be draining the battery even though it works to charge it.  So check that circuit too.

You can access wiring diagrams online for a fee at www.landrovertechinfo.com

Good luck!

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