Technical ignition light on under revs

[sprie]

A shortcut on the battery can get a diode toasted. Touching the jump cables between them while connected on the battery does that.
AC voltage that comes out of the alternator should be under 50 mili Volts.

If even one diode fails two things will happen.

• The DC field will be out of balance with one side of the bridge producing more current than the other. This can be heard and felt as a low pitch vibration originating from the alternator (different than a bearing noise).

• The out of balance field on one side of the rectifier bridge will begin to overload the remaining diodes on that bridge. This overload will cause a DC voltage increase on the failing side as the remaining diodes overheat and begin to allow AC voltage to bleed through. An oscilloscope can verify this condition.

Somehow your voltage regulator cuts the charging too at some point, when you have 12.2 V with the engine running.

I am pretty sure i haven't shorted between the battery nodes.

However...

Whilst it is possible i have been unlucky with the alternator and it was/is faulty, before i go to the trouble of taking it off and sending it back to the supplier to try and get a replacement, I feel i ought to investigate the current setup in case something has caused the issue.
What should i do as part of the investigation?
Is it just to look for a short?
I did replace both the vehicle battery and the leisure battery, so they might be worth checking somehow?

 

[Mike1alike]

Considering the alternator just cuts out whenever, 12.2 V with the engine running, there isn't much you can check. Just that, read the voltage on the alternator post. If there is 12.xx with the engine running alternator is the problem, send it for replacement.
Did it do this light on thing as soon as you bought it (new alternator) or was there some time when it was ok?

 

[bugsymike]

I am pretty sure i haven't shorted between the battery nodes.

However...

Whilst it is possible i have been unlucky with the alternator and it was/is faulty, before i go to the trouble of taking it off and sending it back to the supplier to try and get a replacement, I feel i ought to investigate the current setup in case something has caused the issue.
What should i do as part of the investigation?
Is it just to look for a short?
I did replace both the vehicle battery and the leisure battery, so they might be worth checking somehow?

Would it be an idea to isolate leisure side when testing new alternator and if OK, then see if still good with leisure battery reconnected.
In the past I have gone to start a car with flat battery and it wouldn't turn over even with a good battery until I disconnected the original battery and bypassed it and car started perfectly as original was shorting internally.