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Intermittent Red Battery Light


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I’m hoping someone will be able to assist me in the right direction for getting this issue fixed.


The car in question is a 2011 Ford Fiesta Zetec, 1.25L.


About 2 months ago my battery light came on when the car was sat stationery in a car park & to begin with it would come on every couple of days. Over time it has gradually come on more and more regularly to the point where it now comes on almost every time I drive the car. I do a LOT of miles in this car and am weekly driving 400 miles up and down the motorway, but when the battery light comes on I seemingly have no issue with driving the car and it has never died on me whilst driving. I always know when the light has come on as the engine dips, before the revs sit a lot higher than normal and it normally comes on after being stationary.

2 weeks ago I went to a drive-in cinema and sat with the engine on (battery light on) and after about 1 hour of being sat stationery the car died. I jump-started it and once I was driving again I didn’t have any issues.


1 week ago I started the car on the driveway in the morning and after about 5 seconds it died. I tried again with my foot flat on the accelerator and it started successfully and once again after driving off I seemingly did not have any issues.

I would love to get this fixed as I really don’t want to break-down on the motorway (or anywhere for that matter) but if anyone has any guidance as to what this issue could specifically be so that I don’t need a diagnostic that would be great!


Many Thanks :)

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Does belt look like it’s turning the alternator properly. Are all wiring connectors on alternator on properly and in good order and not corroded etc. Checking with voltmeter at tickover and revving using heavy loads eg lights quickclear windscreen etc might reveal low output from alternator. Most likely needs new alternator but not certain.

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Sounds like typical symptoms of a failing alternator. One day it will just die on you and not restart.

I'd perhaps check the battery voltage before starting (should be around 12.5v), then again once you've started the engine and let it idle for a minute with as many electronics powered on as you can. (around 14-14.4v). You may find you're right on the lower limit so won't affect the running of the car unless you use the stuff that requires a lot of juice (the heated screens, radio, AC, etc.).

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