Testing Output on alternator& auto electrician

burger1979

Hi folks,

just wondering if someone can help me. I think the alternator in the car is going. The wipers are moving slowly, headlamps not as bright as they should be, dash lights not very bright behind instrument cluster, also on the drive to work today the battery light, abs light and traction control light came on. Turned off everything electric and that got rid of the warning lights. The alternator has gone before and there were similar symptoms. I measured the voltage across the battery with the engine running and i got 11 volts, 12 volts across battery with engine off ( am i right in thinking that it should be about 14v across battery with engine running?). anyways i own a ford mondeo and i can see the alternator but with the engine running the belts are in the way and moving so dont fancy putting my hands down there. is there any other way to measure it and and at what points do i measure? i checked the fuses and they all seem to be ok.
also if anyone knows of a good auto electrician in and around sandyford/dundrum area??

thanks,

burger

The Muppet

You shoud be getting 14 volts on the battery with the engine running. Sounds like altenator trouble or a bad connection to me.

El Guapo!

Yeah you should have at least 14volts.
Get your multi-meter and put one lead on the positive terminal on the battery and put the other one on the body of the alternator and check the reading. If its still reading the same low voltage then its definately the alternator. If it gives a good reading of around 14v then you know the alternator is fine and the problem is between the alt and battery (most likely a bad earth/connection)

jimmyw

Yeah you should be getting around 13.5-14 volts with the engine running, but try the same test with headlights, HRW, fan etc. switched on and it should only drop by a small amount.

burger1979

Cheers for the advice folks, I got the car to the mechanic in Navan where i live and he just rang me there to say the alternator is burnt out, this alternator is only in about 1.5 years which makes it frustrating but what makes it even more so is that the warranty on it is only for a year.

From talking to the mechanic it seems that there can be trouble/fault signals from the ECU to the alternator circuit which can cuase the burnout. Going to get a computer diagnostic on the car too to see if it throws up any troubles. So another few hundred quid down the drain on the car.

thanks for the replies.

golfbgud

There's a place on Flower Hill in Navan just down from Filling Station where they do recon and/or new alternators etc...if you are ever stuck?

Think they specialise on the "electrics" side of the business.

It's in off the road so easy to miss it....