LED alternator warning light

[Piledriver]

You probably need a bigger alternator (or supplemental)

Check the voltage at the battery with everything on and while running/charging.

[Ol'fogasaurus]

I agree with Pile driver, if you are running that much power the common practice is to: add a second battery, change over to a higher AMP output alt and go to either a car audio store, to an RV store, or have you local parts house a battery isolator/switching setup that will allow you to charge both batteries but still have one battery dedicated to your audio system. Mind blowing tunes are OK but you gotta be able to get too and from so you can use them.

Lee

[r1cpowdercoating]

well found the problem. I had to pull a battery out for another project I'm working on and founf out that battery was bad! cranked up the car with one battery and the alt. charged right.

[shag55]

I put the circuit described here and it worked out at the beginning but after a while it started coming on very dim. Sometimes I would start the car and the light wouldn't go out. I would turn off and restart and give her a rev then it would go out. A few more drives and now it won't go out anymore. I had a 75 amp alt previosly and it went bad. It over heated and failed. My new alt is a copufire 90amp. It's supposed to have a amp switching circuit to drop output to 45 amps at low rpm and also has a extra fan inside and ball bearings instead of bushings. I thOught this would be the ticket! It's still gets HOT though not as bad. Max temP has been 170 at the front of the windings. Now it's not charging again. Could it be the circuits not cutting it?

[shag55]

I can't seem to figure this out! I bypassed my LED set up and ran a STD light bulb instead and it still has problems. I have to rev the motor up fast to like 4k to get the alt to kick on. Even then it doesn't seem to be putting out enough voltage. I don't get 13+ volts anywhere I check. Post to post on the battery or alt post to ground. I get like 12.2-12.4 even at 2500rpm.

[Piledriver]

I can't seem to figure this out! I bypassed my LED set up and ran a STD light bulb instead and it still has problems. I have to rev the motor up fast to like 4k to get the alt to kick on. Even then it doesn't seem to be putting out enough voltage. I don't get 13+ volts anywhere I check. Post to post on the battery or alt post to ground. I get like 12.2-12.4 even at 2500rpm.

not the idiot light then.

Sounds like the alt or the regulator, or perhaps a cell died in the battery and it can't keep up..

Charge the battery overnight (disconnected) let it sit awhile also disconncted, should read ~12.5v.
(you know the drill) perhaps have it load tested.

I got pissed and converted a bum new internal regulator T1 alt to an external using a fan housing mounted T4 external reg many moons ago, not hard.
...not really suggesting it, just that it's an option, the external T4 regs seem easy to come by, OReillys sells them w/lifetime warranty.

[shag55]

Don't think it's the battery. My charger has a auto loat test on it. I charged it and it's 12.4v at the posts. It's a oddesy 1200 by the way.

[Piledriver]

Assuming the battery is good, then the alt cant keep up with the load, or the regulator is bad.

In the old days, you would simply full field the alt to test it/bypassing the reg, but depending on your electronics (EFI, radio etc), that may not be safe to do in-car.

[Steve Arndt]

What reading do you get when connecting your volt meter between the battery negative, and the alternator housing/case ground? Should be zero or close.

[shag55]

Will check tonight.

[shag55]

I get .0-.01 from the battery- to the alt housing.

[shag55]

I'm getting 11.23v from the LED dash light to the alt body.
I'm getting 12.1v from the temporary light bulb to the housing.

[shag55]

I put the rebuilt alternator on and a new interstate battery and a incandescent light bulb in the dash.
Started up all was well, light went out and charging at 13.5v.
After running a while and turning it off it has become like the other times. Have to rev it up to get light to turn off. Gets worse when it gets warmed up. I have to rev it hard.
I'm getting 11.6v from the dummy light wire to the alternator housing.