battery light on

[vs2DSIRE]

hey all again just wondering what could a battery light on mean . Changed my alternate because i had a spare but its still on . And my battery is a full charge but once i drive little it dies ?????

[304runner]

You have a dodgy alternator in that case...

Unless the alternator is new I wouldn't trust it. I had the same issue with 3 different ones.

The best way to see if the alternator is working is to get a multi-meter ( a few bucks from supercheap) and when the car is running place the Multi-meter on the battery and it should read about 14.4 to 15 volts.
You can also check it from the blot on the back of the alternator as well.

And check you havnt broken one of the small wires going to the alternator.

[Daz111]

I have had this happen to me a few times, turned out the brushes on the regulator were worn down so far that there was no pressure on the alternater slip rings. My regulator type in each case is RE60, available from a number of places or you can just get new brushes, de-solder the old ones, throw them away and solder in new brushes.
If you re-used the same regulator then it may be faulty, if the replacement alternater had a second hand regulator then it could be the same problem on both regulators, I speak from experience of exactly this situation occurring.
Remember to disconnect battery whilst replacing regulator or you will experience some arcing & sparking that you do not want.
Regulator is only connected to alternator by 2 small bolts/screws.

[DAKSTER]

Buy a regulator with brushes already attached for about 60 bucks. Disconnect battery, unplug one plug, undo two screws, remove old regpack.
Fit new regpack, replace screws and plug, connect battery and start the car.

If the battery light is off, problem solvered boss. If its still on, then the alternator needs diodes replaced or worse. See your friendly local sparky... or it may be cheaper to buy another secondhand alternator. Try the regpack first though, you can always stick it into a secondhand alternator later, money not wasted.

Its usually the regulator or brushes so a regpack will most likely fix it, and if you have transplanted your old regulator onto the 'new' alternator that would make it even more likely. Its the cheapest possibility but also the most common, so worth a go.

[HSV5L]

Alternator should be the problem.

[wamboin23]

check the fusible link at the battery. it goes from the positive terminal, to a small black plug about 2 inches away.

this is the battery voltage sense for the alternator. if it's broken/burnt/unplug, repair as required.

[1yldvs]

i have the same problem but only did it when i changed the battery and i dont have any problems with flat batterys. but when the revs are high the light turns off. any ideas what it could be? cheers

[hako]

i have the same problem but only did it when i changed the battery and i dont have any problems with flat batterys. but when the revs are high the light turns off. any ideas what it could be? cheers

Could be a bad regulator/brushes - see daksters post.

[1yldvs]

no worries ill check it out

[inasinman]

Could also be deteriorating positive cable that goes from the alternator +ve to battery +ve terminal.

[hako]

Could also be deteriorating positive cable that goes from the alternator +ve to battery +ve terminal.

I'll second that - they go brittle and crystallise from heat just where they join the alternator...fracture internally and can cause many problems.