Thread: Voltage from Alternator ?(what shuld it be?)

Your alternator voltage depends on the current draw, engine revs, the temperature and the variability of the alternator regulator. Run the engine at 1500rpm or so with the lights off, test, then with the lights on. Voltage over 13.5V indicates battery is not discharging. 14+ V is what you would expect with a cool engine bay and no load. Don't expect much charging output at idle.

Good point bee utey.

James, with two low batteries, a small capacity alternator and the engine at idle, those reading may be fine.

Sounds like an excuse for a good long drive and then see what the voltage is at the batteries.

Thank you bee utey,
I will give that a go.
Sounds like very good advice.

Regards
James

Thanks Tim,
I have been looking for a good excuse for a trip.

Regards
James

I tested my 300TDI Disco voltage at idle no lights just a few days ago and it was over 14v. From memory about 14.5... Could check again tonight if you want an exact measurement.

Originally Posted by Judo

I tested my 300TDI Disco voltage at idle no lights just a few days ago and it was over 14v. From memory about 14.5... Could check again tonight if you want an exact measurement.

My Nanocm says 14.5 - 14.6 Volts at idle.

Thank you to all who gave me advice i have checked my alternator and it is now 14 volts, I don't know what happened but looks like it is back to normal. I will be keeping an eye on it.

Thank you all very much.

James

I have recently sorted out a long ongoing problem with my 300tdi charging circuit.
I had my second battery going flat and needing to be maintained every month or two.
I had good voltage at the alternator and batteries.
I thought for a long time that it was my battery controller and looked into alternatives, but in the meantime I looked into the wiring and earthing.
I checked the current at the batteries and noticed it was non existent.
Short story - Finally found a replacement regulator, old one was worn COMPLETELY down, now all is amazing. Headlights bright, dash bright, cranking battery is full and strong.
Now I will put some money aside for a new headlight switch as this one will fail with all that current.