Intermittent Red Battery Light

[jsanders]

Hi,

 

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 :)

[Edge of Reason]

Sounds like your alternator is not charging. 

[isetta]

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.

[Luke4efc]

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.).

[Gill M]

My 2012 Focus presents the same problem and failed the other day after about 20 minutes of driving with the red battery light on - it usually goes off and I am fine - this time it did not - I was trying to get home and I did but only in first gear at 10 mph for the last mile, as it is automatic and would not change up, I don't think I had hazard lights either although the indicators were clicking in the car as cars following were confused.  When I got home the battery was flat, but we charged it and the car recovered including it's brain and gear functions.  We examined the battery and alternator but both appear to be fine, we called the AA and he put his diagnostic computer on it and he could find no fault.  Took it to the garage following day they looked and found nothing wrong and refuse to replace the alternator as they said it might not solve the problem and it would be £300 spent unnecessarily.  So battery is fine and alternator fine - anyone with any other ideas please?  I am afraid to drive it now as I do not want to get stuck on a smart motorway or anywhere I can't safely pull off the road, especially if the hazard lights wont work.

 

[Edge of Reason]

If the battery is fine and alternator is fine, I wonder if there is a drain somewhere.  Like a relay or some other electronic item is draining current. 

Fair play to the garage for not replacing the alternator.  A mechanic with a conscience is nice to see. Clearly someone who thrives on reputation. 

[alexp999]

battery drain doesn't cause the battery light to come on.

The battery light means the alternator isn't putting out enough voltage and you are running on battery power.

If it's not the alternator it could be the wiring, preventing the smart charge working, or on this year of car, I think the BCM controls the charge, but someone will be along to confirm I'm sure.

It doesn't sound like your mechanic has said the alternator is fine, just that it MIGHT not be that.

What is the voltage when the engine is running? They usually have a default safe voltage the alternator operates at if it can't get a comms signal.

[TomsFocus]

The alternator should be able to produce far more current than any battery drain could take with the engine running.  If the alternator genuinely is fine, I'd say it's output is being restricted by the PCM for some reason.

The Mk3's have variable rate charging as well as SmartCharge.  So it's a possibility that the PCM thinks the battery charge is higher than it actually is.  In the short term, you can unplug the SmartCharge plug which should default the voltage output to 13.5v.  Not great long term, but should at least get you home if necessary in future.

I assume the thick battery cables and terminals have all been checked?