Ford Transit - Battery light coming on and off towards end of j

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Sun 11 May 2025 13:37
Ford Transit - Battery light coming on and off towards end of j - driverofavehicle

What is the likely cause?

I was on the longer driver today, about 2 hours after all, and noticed towards the latter 3rd of the journey the battery light was on, then went off after a couple of minutes, then came on again maybe 15 minutes later and stayed on until I got the to destination.

I really didn't want it to be the alternator having died again as I only got in not a year ago. I took a look under the hood as soon as I parked and put the voltmeter on with engine stopped and it read 12.9/13.0v. So fully charged right? I know you should let it rest a while to get a true reading but in time when it has been working normally and checked the voltage I didn't seen it deviated much above the suggested voltages for full charge In fact I have never read it as high as this, usually 12.6 or so but then again I don't usually drive that far and check. If the alternator hadn't worked at all I would be looking at much lower voltages right? It is a normal sealed batter btw, not lifepo4 or the like.

I ran the engine and saw the belt spinning so relieved to see it is still operational. I just read an article which advises to put the voltmeter on when the engine is running, which I haven't done yet, to look for a jump in voltage on the battery to indicate the battery is charging.

Likely causes?

I will also note that it is a new battery, bought only last year.

MOT test is tomorrow so fingers crossed it won't affect that! Have to try and solve it if is going to be an issue, only a few hours!

Edited by driverofavehicle on 11/05/2025 at 13:40

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Sun 11 May 2025 14:33
Ford Transit - Battery light coming on and off towards end of j - elekie&a/c doctor
How old is this van ? Charging voltage at idle should be around 14 volts. Need to check that first.
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Sun 11 May 2025 18:01
Ford Transit - Battery light coming on and off towards end of j - driverofavehicle

About 20 years but don't hold that against it. It was in vgc when bought, only a couple of years ago, and barely used by previous, apparently original, owner, who had it kept in storage from what the dealer told me.

I had it inspected by a mechanic before purchase and they confirmed the same.

Yes, since posting I put the voltmeter on the battery again and started the engine and it jumped to the 14v region. Also the battery light went out after a about 20 seconds.

We shall have to see if it was just a blip.

Edited by driverofavehicle on 11/05/2025 at 18:04

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Sun 11 May 2025 22:32
Ford Transit - Battery light coming on and off towards end of j - bathtub tom

Yes, since posting I put the voltmeter on the battery again and started the engine and it jumped to the 14v region. Also the battery light went out after a about 20 seconds.

I would consider twenty seconds to be too long. I'd expect it to extinguish as soon as the engine's running. Alternators seem to either work or not in my experience.

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Tue 13 May 2025 08:30
Ford Transit - Battery light coming on and off towards end of j - driverofavehicle

I would consider twenty seconds to be too long. I'd expect it to extinguish as soon as the engine's running. Alternators seem to either work or not in my experience.

It has actually gone back to going out at the expected time now.

I took the van for MOT yesterday and passed that thankfully.

I went for the quick 10 minute or so drive to the shops this morning though and it came on for maybe 30 seconds again, that is after having immediately gone off after starting the engine, then went out again.

I have looked under the hood a couple of times now, when parked, and seen the alternator spinning happily.

I wondered if it might be a loose connection somewhere. I had a cursory wiggle and the battery terminals and the alternator and none seemed loose from that initial inspection, though doesn't rule it out totally; just nothing obvious.

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Tue 13 May 2025 08:40
Ford Transit - Battery light coming on and off towards end of j - elekie&a/c doctor
What age is the van ? It’s likely to have a smart charge alternator.
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