Battery drain help needed

atromford said:

Batterys got good voltage if left disconnected tho will have to leave it for a period and double check there’s no drop on it. haven’t checked all the relays and will have to strip it down and locate the alarm battery/ fuse

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Voltage on it's own is not always guaranteed to show condition of a battery. You can have a battery sitting at 13.3V that still might not start the car.

Charge it fully, leave it disconnected fully for 48 hours then attach to your Landy then attempt to start. Have your meter across the terminals and watch the voltage when it tries to start, see what it drops to during cranking - that is the best load test for your situation.

If you cannot wait this long, charge it fully, leave it about half a day then have a load test done in it by a garage or parts place - if their tester doesn't have 2 bloody great pins going into it, or 2 bloody thick wires going into it, it is not worth a fart. Load means load and heavy connections to the tester is reasonable sign that the tester will pull a reasonable load. You really want 100's of amps on a test - something to simulate a starter under load.

There was a parts guy local to me who had a "load tester" it had two little clips on it and a piece of coiled wire about 5mm dia. which came up to a little meter and a button - I asked him what sort of load it was putting onto the battery and he said "Mega, Loads!" I didn't even bother to explore further.

400 mA is too much resting draw, but remember to wait a few minutes after shutting off the ignition for the ECU to go to sleep. It should be below 50 mA (0.05 A).

If you’re sure you’ve pulled every fuse and the draw won’t go away, check the unfused connections - starter and alternator, for example. The alt could have a bad diode. You have to keep disconnecting stuff until the draw stops.

You can also check the alternator is putting out a good 14 V, even under heavy load (lights and blower on etc.), then check the ripple (AC) by switching meter to AC volts and measuring between a good nearby earth and the B+ terminal. Ripple should be below 0.5 V and ideally around 0.1 V, as I recall.

If the alt is good I think you can still get the battery analysed for free at Halfords. But you have to get that draw sorted, though.