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Alternators and Alternator light

nickhassonnickhasson
I'm getting ready to add a bid of electrical gear into the car. Heated seats, two amps, some led interior lights, alarm and keyless push button start. I'n prep for this I replaced my 55 amp alternator with a higher output one.

I purchased an EMPI 90amp usa made alternator. Since installing my alternator, the alternator light comes on when i start the car. Once I give it some rpm's over 1200 it goes away. Once in a while the light will stay on. Next time I start the car it will go out.

Maybe a voltage regulator? Its in the alternator, so is this brand new alternator bad? Do i need to replace the whole thing? Or can i get a voltage regulator for it?

I searched the forums and found a tip from dr. clock to reverse the + and - on the light. That did not work and caused the tach to go nuts.

Also, does anyone know how many amps the car pulls with everything on? Would the 55 amp be enough. I know the heated seats pulls 10 amps each. So i'm thinking 55amps is not enough.
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nickhassonnickhasson
I'm getting ready to add a bid of electrical gear into the car. Heated seats, two amps, some led interior lights, alarm and keyless push button start. I'n prep for this I replaced my 55 amp alternator with a higher output one.

I purchased an EMPI 90amp usa made alternator. Since installing my alternator, the alternator light comes on when i start the car. Once I give it some rpm's over 1200 it goes away. Once in a while the light will stay on. Next time I start the car it will go out.

Maybe a voltage regulator? Its in the alternator, so is this brand new alternator bad? Do i need to replace the whole thing? Or can i get a voltage regulator for it?

I searched the forums and found a tip from dr. clock to reverse the + and - on the light. That did not work and caused the tach to go nuts.

Also, does anyone know how many amps the car pulls with everything on? Would the 55 amp be enough. I know the heated seats pulls 10 amps each. So i'm thinking 55amps is not enough.
Jim KellyJim Kelly2013 SAS coupe-Fiji
Nick,

Here's an easy check to start. With the engine off, disconnect your battery ground and place an ammeter between the battery ground and the chassis. Any current you see running is a drain on your battery and could indicate the reason why your alternator seems to be putting out when you start up. Your alternator warning light may be functioning properly, just telling you that its ouput is peaking at startup as it tries to bring your battery up quickly. Have you been listening to your car audio system while you work on it? Any other circuits energized while the key is off?

I'm not sure if you have already wired in your extra circuits or not. Your symptoms seem to indicate that when you increase alternator rpm from idle speed, charging levels increase, and the warning light goes out, as battery voltage level increases to normal. I'm sure others will chime in.
J justinh
Having to rev up the engine a bit before the alternator kicks into operation can be normal. If the light stays on then the resistance in the light circuit could be too high (check all connections/fuses) or the alternator diodes, regulator or brushes could be bad.

Check the voltage at the B+ and D+ terminal with the engine running. If the alternator's working they should both be at 14.0-14.5 volts. With the engine off and ignition on, D+ should be at 0-3 volts and B+ should be at ~12 volts.
nickhassonnickhasson
I'm not working with the stereo on. When I read the voltage at the alt, its 12.5 at idle and runs up to 14v once the engine gets the rpms up.

No new wiring has been added. I wanted to make sure that this problem was solved before adding anything to the equation.

I will have to check the belt tension. It was good after I installed the alt, but maybe it needs attention.
coolrydecoolryde
Nick,

What you are saying is an indication that the Empi (poor quality) Alternator is malfunctioning. Your best off buying a good quality Bosch unit. We had one of those Empi alternators go out and peak charge at 18 volts. When this happened every electronic part, including the Redline fuel injection ECU fried. It just is simply not worth the savings of buying an Empi part.

Good luck.
coolrydecoolryde
Nick,

First you should read the specs on the items you want to use. You might find that they do not require as many amps as you are trying to set up. Also Keith made a good point about your harness being able to handle the load. If the wire going from the alt to the starter is the standard 10 gauge, you may need to swap out the wiring and or add a second 10 gauge wire.
An easy way to check this is with the car running and everything you can turn on turned on (lights, wipers, stereo, heaters, etc...) Leave them on and run the engine for 15 minutes at 2000 rpms. Go back and grab the alt wire, if it is hot to the touch you need a larger dia. wire.

On a side note:
The SPEEDWELL Oval I built has 2 amps totaling 800 watts, heated seats, and a slew of other goodies and it not only runs a Bosch 55 amp alt, but does it with an underdrive pulley (meaning it is turning at a slower speed.

Good luck....
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