Is my alternator working ?

[Greylensman]

Hi, my Terrano - 2003, 2.7TD, 28kmiles - is used about every other week (2nd motor and for caravan towing) and I had to change the battery yesterday - the vehicle had stood for 2 weeks and the battery was totally dead, no voltage at all. The battery was about 3 years old but I've not had a problem leaving the motor this long before.

With a new battery on the engine fired up and ran (after all the various flashing lights stopped flashing!) and I checked the battery voltage with all the lights on and at just over 1000rpm, the voltage is 14.2v.

Since I cannot check the charge current, I was wondering if this voltage reading is enough to say that the alternator is working OK ??


Thanks.

 

[rustic]

Hi, my Terrano - 2003, 2.7TD, 28kmiles - is used about every other week (2nd motor and for caravan towing) and I had to change the battery yesterday - the vehicle had stood for 2 weeks and the battery was totally dead, no voltage at all. The battery was about 3 years old but I've not had a problem leaving the motor this long before.

With a new battery on the engine fired up and ran (after all the various flashing lights stopped flashing!) and I checked the battery voltage with all the lights on and at just over 1000rpm, the voltage is 14.2v.

Since I cannot check the charge current, I was wondering if this voltage reading is enough to say that the alternator is working OK ??


Thanks.

To be honest, I trickle charge my mav when it's in the garage. I even have a fused 2 pin socket on the bumper, to save lifting the bonnet.
My mav is difficult to start if left for more than a week.
I have a solar panel facing the sun when on holiday.

The radio, alarm and ECU drain the battery, and natural discharge of the battery.

You battery voltage when charging at 14,2 V looks about right, but check it when you also put full beam on, the heater fan and the rear screen heater, it should still hold 14 -14.2 volts.

But to be totally flat after 2 weeks, then something must have been draining it, interior light, faulty alarm?.
Or maybe you are not driving it enough between storage.

Check the voltage twice a day, or if you can get a 10 Amp meter in line with the battery lead, you will see what the discharge is.

My daughter's battery was flat over night, no lights left on, but there was a constant 3 amp discharge, I disconnected the alternator and the discharge went to a few mA, radio, alarm, ecu etc. That's ok.
Fault was the diode block in the alternator.
Hope this helps, apologies for another long post.
Regards, Rustic

 

[rossco]

Going by the voltage on idle your battery is charging.(alternator working)
Next step would be to see if your battery is holding the charge.
When you park it up at night check to see what voltage the battery is and then again in the morning. If you have a big difference you have either a fault which is draining the battery or it's not holding a charge.Pay to get it checked out properly with a battery person who has the right gear for further analysis