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Battery drain on Caterham with Rover engine 1996
Moggi - 5/5/15 at 07:41 PM

For a long time there has been a power leakage while the care is parked. I have solved in a way by using a main switch, but if I forget to switch off, the battery will be flat after 24-48 hours. Or destroyed after days.

I have measured the leakage:
When main switch is turned on, it use 0.01A - should be OK
When ignition is on, it use 5A and drops down to 1.04A - should be OK
When ignition is turned off, it drops down to 0.48A - that is too much and will drain the 28A battery in less than two days.
If i disconnect either of the two connectors to the relay unit, it drops down to 0.01A.

I bought a used system from a Rover K216 - K16 engine. I replaced ECU, relay box, immobilizer and key fob.
But the symptoms was exactly the same. Either the used parts had the same problem, or the problem is located elsewhere.

Is this a common problem that can be solved?

There is a similar problem described in 2010; Rover/MG hard to track down battery drain --- how to fix.

rusty nuts - 5/5/15 at 08:21 PM

Try disconnecting the alternator and measuring the drain

Moggi - 6/5/15 at 12:32 AM

I have tried to disconnect the alternator also. I read that hint elsewhere before posting this.

Anyone else with same problem?

[Edited on 6/5/15 by Moggi]

baz-R - 6/5/15 at 01:01 PM

alternator diode has gone down i would say

Moggi - 6/5/15 at 07:52 PM

Sounds very plausible with a faulty diode, but...
After ignition is turned off it measures 0.48A, then I disconnected the alternator and it still measure the same, steady at 0.48A.
If i disconnect either of the two connectors to the relay unit, it drops down to 0.01A. Something is faulty holding some relays.

I suspect the engine immobilizer, or a faulty relay unit, or the ECU. I have also checked the ground and different connectors.

britishtrident - 7/5/15 at 12:32 PM

I have seen this before on Rover 25 it was the receiver coil for the ignition key transponder chip had overheated and shorted out. This seems to prevent the system from going into sleep mode. Normally the receiver coil is an annular ring surrounding the ignition switch barrel.
Not all Rover had the transponder so the system will work with it disconnected BUT the disarm button on the key fob must be pressed every single time the engine is started.