Faint battery light!

[Cavdvm]

Evening all drove home tonight and the battery light came on but only very dim. As the journey progressed the light went off completely , luckily I have a volt meter in the car, it went from just under 13 to 14 volts, also the battery is new too. Is my alternator on its way out?

[Robsey]

Before getting giddy about the alternator, check that the cables are clean, secure and intact.

If you had the lights, blower fan and the heated widow demister on, then this could pull the voltage down.

Voltage should be between 13.5 and 14.9 volts on a healthy alternator and battery with everything else off.

Of course the only way to be 100% certain IS to replace the alternator.

[Cavdvm]

Cheers pal also I only do a short journey of 7 miles every other day could this be another reason I put the volt meter on the battery when it wasn't started and it read 12.

[Robsey]

Indeed it would.

Short journeys don't give the car very long to recharge the battery.

They do say that for every crank of the car, you need 15 minutes of steady driving-
to replace the charge used up by cranking.

Oh and icy / frosty mornings also weaken the battery a little.

[Cavdvm]

Can u test the alternator ??

[Robsey]

More or less in the way your volt tester does.

Measure across battery or even cig lighter terminals

Ignition on, engine not running.
Probably about 12.7 volts.

Engine running with al lights etc off, you should get 13.5 to 14.9 volts.
Especially revving above 2000 revs per minute.
You are looking for as close to the high 14 volts as possible.

[Cavdvm]

Drove home tonight, no light on ! The only thing was the was a slight whining on start up from the alternator area but so went once the engine was running

[iangsi]

Drove home tonight, no light on ! The only thing was the was a slight whining on start up from the alternator area but so went once the engine was running

Could be the belt is a little loose & slipping.

[Cavdvm]

Hi just a update, the battery light still comes on so I do think the alternator is slowly dying! Question is am I doing long term damage by still running it ? Also it's a v6 cav and all the alternator companies say there is loads of variants of the alternator, will I need to remove it first in order to get part number etc or by jacking it up will I be able to find said part number ? Cheers

[Envoy CDX]

Use a 100amp alternator from a Vectra B, bolts straight on and you're golden. However, I would look at the cheapest option first and change the belt, they can stretch / slacken with age and wear.