Thread: Alternator failure without warning - can it be anything else?

HI All,

Thanks for your posts and valuable information.
I now find myself in a similar position, but with a possible twist. I have a very new battery on my 2007 TDV6, which continues to start the motor without any issues, but the battery light has been on for 2 days now. The twist is that the charging system seems to be working fine, reading 13.5v with the motor running? However, the light is clearly showing a fault with the charging system!!

Any ideas??

Check the voltage at idle with all the lights on as I suspect there's 1 open circuit diode that will cause the alternator to not be able to keep up the voltage with more load.

Thanks Graeme,

All lights on including full beam = 13.48v
All accessories (radio, DVD player) = 13.46v

I also have a Traxide DBS installed, so all these figures are with this connected. I tried disconnecting the feed to the second battery expecting at least some change in the volts, but still 13.5v!!??

Puzzling!?

Does your vehicle have a load sensor attached to the negative battery terminal? If so there may be a problem with that device. There could also be a problem with the regulator circuit that operates the light as the light is just a crude indication to the driver that the alternator is charging or not. I would not let it go for too long lest the battery isn't receiving full charge.

Hi Guys I have just come back from a trip to South Australia on the second last day travelling home in my D3 tdv6 the battery light came on I looked for a spot to pull over which took a few minutes when I braked to slow down the light went out. Couldnt find anything wrong the same thing happened the next day where it stayed on for 5 minutes then went out again. Since being home for 2 weeks I have checked the battery volts first thing in the morning showing 12.5v before starting then starting with lights on it charges at 14.8v after driving it for about 10 minutes the chargeing drops to 13.4v to 13.6v. Havent had the battery light come on for two weeks. My first alternator packed it in after 155,000klms this one is 11months old. Have got it booked in today before the warrenty runs out on it to see if they can find anything. Seems abit high at 14.8v first thing any thoughts

Nothing wrong with 14.8V soon after it starts charging especially in cool weather.

Thanks Graeme, Everyother time I have checked in the past its always been around the 13.4vmark. It is with the repairer at the moment. Wanted them to see the battery fault logged so if they cant find anything at the moment at least the fault has been shown while in the 12 month warranty period.

Hi Guys, Called repairer and he told me they are replaceing my 10 1/2 month old alternator with a new one. Hope all goes well as I am going away for the long weekend at the end of the week