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MG MGF Technical - Battery Light Stays On

Hi All,
I've searched the site and found several similar stories but none that seem identical. I recently went down to Cornwall in the MGF and the alternator drive belt went. Long story short..AA took me to a garage where a new belt and tensioner were fitted and off I went again. Shortly afterwards the battery warning light started to stay on after starting the car but would go off if the engine was revved a bit. This slowly became worse and now the light stays on for about five minutes almost every time I start it then goes out. Any ideas?
M Richardson

Sounds like the drive belt has worked loose, since it is a new belt. Are you getting any noise like squeeling if you rev it shortly after starting? Just after starting the, alternator works harder topping up the power used by the starter motor, this makes the alternator harder to turn for a short while hence the slipping when first started, as soon as the battery recovers the alternator is easier to turn so the belt no longer slips. It may slip again if you run the heater of headlights, as once again the alternator is under load.

Gary Luxon

Gary,
Thanks for the advice. I'll try re-tensioning the belt. Today, I opened the engine cover and started it up and, sod's law, the light didn't come on! I took the oportunity to test the output and at tick-over it's putting out 14.3 volts so I think the alternator itself is fine. I'll message how I get on with it after re-tensioning.
M Richardson

With the bodywork used as a link between battery and alternator, you may find the earth straps, positive leads and all connections worth checking.
Charless

Tightened the belt up and so far so good. Thanks for the advice.
M Richardson

This thread was discussed between 23/04/2013 and 28/04/2013

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