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MG MGF Technical - Battery Life

What is the normal life of the battery when the car is not used. I have a blinking red light on the dashboard but no other apparent voltage drains and the battery goes below 12v after a few days. I replaced the battery and it is still the same.

Clive Skelhorn

You could try disconnecting the battery earth and connecting a multimeter between the earth lead and the earth terminal of the battery, set it to the current setting (most meters are limited to 10A but this should be fine) and measure the drain. Then try pulling out fuses one by one and see where the power is going.

The car should use some power when its idle (alarm etc.) but I would expect it to last for several weeks like this.

Happy hunting.


Andrew Smith

A D Smith

I bought a battery conditioner, connecetd to battery when car not in use, before this the battery got very low after about 10 days if the car was not used. Extendes the life of the battery too.

Cheers Alan

Hi Clive, I have recently had the same problem, check my post. It was draining at 0.1 amps so if I left the car too long it wouldn't start. After fitting a second hand timer unit the drain is now 0.03 amps. This work was only done last week so I cannot confirm yet whether it has solved the problem. I may use the car today when it will have not been used since Wednesday. With a healthy battery and no excessive drain a car should start even after being left for several weeks. Try Andrew's advice to determine the none running drain.


20mA should be the usual battery load on a shut down ECU.
Shut down happens latest 45 minutes after ignition off.
(Brown-Pink cable in the engine bay must be 'dead'.

It's a common fault at Rover ECU's that the shut down circuit fails for some reason. It happened already at the earlier MINI ECU's...

If so, then it could be repaired inside by very, very enthusiastic electronic freaks ;-)
Or change the ECU and immobilizer ECU together to a second hand kit.


ooops, also just found Dave's post here
That's about the MFU (multifunction unit) failed.

Dave & Dieter,
thanks for your comments, I started testing and when I put a fluke (meter) on the negative side of the battery between battery and earth I see firstly a drain of about 0.9amps with what sounds like a very quiet pump running and then the noise stops and it drops to 0.43 amps and stays there. This seems much like your indicated 0.5 amps on your first check. I will try and trace which fuse powers the timer and see what happens when I pull it out.

Clive Skelhorn

This thread was discussed between 03/01/2009 and 07/01/2009

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