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MG MGF Technical - Battery drain

The (recently replaced) battery of my MGF is draining to the extent that if I don't use the car for four or five days it won't start.

Could this be caused just by the normal operation of the immobiliser/alarm system, or is something more sinister likely to be at work?

Any suggested solutions? (The other half does not approve of the isolator-switch-under-bonnet option...)

Normally it takes between 2 to 4 weeks to drain the battery if left standing so i wouls assume that there is something else draining it.

Check the boot lid light and underbonnet lights extinguish when the lids are closed. Do this by feel, if they are on all the time they will be hot.

Remove bulbs as a temporary cure.

Scarlet Fever

How old is the battery? if more than 3 years old then it's probebly a new battery job.

Other than this the imobilizer on the F is quite good, I have left the car for weeks (some people here for months!) and had no trouble starting

The F has a known problem with:
Door locks - they fail and the car thinks the door/bonnet/boot is still open, if this is the case then the car will fail to superlock.
ECU not turning off, the MEMS ECU stays active for about 10 mins after switch off (time dependant on temp etc), the relay has been known to stick in the 'ON' position, giving much higher drains. You can test this with an ammeter, but bridge the connections with the meter before you break them apart, not break and then bridge, because this causes a power surge and will blow your meters fuse.

Compare the readings with just stopped and 1 hour later.

Also make sure that the battery is getting a full charge, using a voltmeter across the battery you should see 14.5 volts
Will Munns

Ive had a few customers in the past complain of this... If I get chance I'll find out what the cure was ...

One of the main problems you get with bad starting, which I have seen memo's for on the F were crap leads... I recommend to anyone to buy the higher performance ones
Mr E

I replaced the HT leads on mine with some better ones and the battery lasted for a couple of extra years before I had to replace it (after 6 years from purchase). Also try WD40 on the HT lead contacts, or cleaning them. See other posts for where they are but sort of at arms length in the middle/right straight down under the oil filler.


This thread was discussed between 30/03/2004 and 02/04/2004

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