battery or alternator - please help dignose these symptoms..

[unutterable83]

Hello all,

13.3 Volts running
11.9 Volts running + all electrics (aircon, indicators, heated screen, full beams)
11.6 Volts turned off, falling by 0.1V every 10seconds.

It drives fine for 2-3mins, then the headlights get dimmer and dimmer, untill it eventually wont idle, i have to keep the revs up to keep it running. Its drives perfectly in gear, only struggles at idle.

How much torque does the alternator require to drive - i did spill a bit of oil on the belts and wonder if the alternartor is turning?

Thanks for your help!!

Greg

[14-7]

With engine running it should be charging at over 14 volts.

[unutterable83]

so, would you say alternator? do i need to buy anything else or a straight swap job? (the belts new) Cheers.

[Nigel Worc's]

Due to the price, if you're not sure, why not get it checked ?

[Vee]

Sort the belts first (relatively easy) then look at the alternator.

[E30M3SE]

A friends (BMW)Mini was giving exactly these reading recently, changed alternator and normal service was resumed.

[jhfozzy]

Where are you checking the voltage?

We had a corker the other day where the eventual fault was the main battery cable from the battery in the boot forwards to the alternator. The cable ran under the car and was slowly corroding away, causing a voltage drop.

We were getting the same symptoms as you with a meter at the battery, but checked at the alternator, the voltages were correct.

[Patrick Bateman]

Everyone will automatically say alternator but make sure you definitely know before going ahead with it.

Oh and make sure an auto electrician looks at the car and not a mechanic.

[road_rager]

Battery sound fked for a start, resting volts should be higher than that.... Get battery checked out and take it from there

[littleredrooster]

road_rager said:

Battery sound fked for a start, resting volts should be higher than that....

Not when it hasn't been charging...