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Battery light on and off

Tomsky

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Accord 2.2 ctdi
Hello!

I have a very strange issue with my accord (VII gen, 2.2 ctdi). The alternator was replaced in August but recently the battery dashboard icon has been coming on and off. I replaced the battery as it was quite old but that didn't make a difference.

What is strange is when the light comes on. For example, today in the morning I started the car and started driving. The battery icon came on shortly and was on for most of the journey (about 10 miles). It only went off when I stopped at traffic lights. I used the torque app connected to the obd port to check the voltage - it was always between 11.6 and 11.9 regardless if I had the ac or lights switched on or not or if the battery light was off.
Then I switched the engine off and after about 10 seconds turned it on again. The icon never came on and torque was reporting the voltage of a round 14v for the whole journey. Again, lights or ac on/off didn't make any difference.

It now seems to happen all the time - start car in the morning - problems with charging, restart the engine - charging is correct.

There are no fault codes.
I checked all the alternator and battery connections and earthing and they look fine.

Any idea what might be causing this?

Thanks!
 
Last edited:
Sounds like a bad alternator mate.
 
Sounds like a bad alternator mate.

Cheers, it's just weird that sometimes it works sometimes doesn't. The alternator is still under warranty so going to take it to the garage where it was fitted, the only problem is that by the time I get there and restart the engine its going to look like its charging.
 
The alternator contains a regulator which on certain designs is replaceable.

In the meantime check the earth points under the bonnet, not just the small ones (there is a strap that can cause issues on the suspension strut - rhs).
 
I took the car to the garage which replaced the alternator (formula 1 autocentres) - they checked the charging and it was fine (which doesn't surprise me as its usually OK after you start the engine again) so they say the problem is elsewhere but they're not car electricians so they cannot say what it is. So it looks like i need to find a car electrician who can diagnose the issue.
 
There isn’t anything else that will cause this issue mate. Keep an eye if it happens again, replace the alternator
 
Sounds like a sticky regulator as mentioned above. I would give the alternator a few light taps with the end of a screwdriver when the warning light comes up. Other than that, definitely take off all the earth points, clean up with sandpaper or dremel then retry. Is the alternator still on warranty?
 
Are you sure the alternator belt is tight? Have you had the battery properly tested?
 
Yep, the alternator is still on warranty, but they refuse to replace it cos when they tested it today it was working fine. I have no reason not to believe them as I know that when it works, it works just fine.

The alternator belt appears to be tight to me, I'm no expert but it definitely doesn't appear loose. The battery has been replaced this week and that didn't make any difference so we can rule that out.

Regarding the earth points, how many there are? I could see 2 (one coming from the battery, the other one on the LHS), are there any more?

Thanks all for all your answers, really appreciated it!
 
There is one under the battery tray which is a right sod to get to. I made a thread about removing a superfluous metal link on the forum about a year ago.,
 
There is one under the battery tray which is a right sod to get to. I made a thread about removing a superfluous metal link on the forum about a year ago.,

Thanks, I'll see if I can get to it over the weekend, hope the weather gets a bit better by then :)
 
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