onefastrx712a

iTrader: (1)

Im having problems with my voltage.. every time I turn anything on the volts drop way low. I have a 87 base model and the alt is new, and i have a new red top batt. Do i need a bigger alt.? I don't even have any amps, fog lights, or anything else that would be draining it. Could it be in the wiring? Any help would be appreciated.

jjwalker

More than likely your alternator has just aged and weakened. I have the same issue as well, but it can still reliably charge the battery at all times.

Get a voltmeter and test between the two battery terminals at idle. It should read 14.4v or within a few points of that. Turn all the accessories on, AC, headlights, and have someone help by stepping on the brake pedal. Then test. It should be over 13.6v.

Anything less than 13.6v and the battery wont charge. Mine dips to 13.7v with all of that stuff on, which means the alternator is weak, but not so weak that you are comprimising the battery. Just look forward to needing a replacement in the future, but you don't neccessarily need one right away.

lastphaseofthis

iTrader: (8)

New alternator and battery? yeah.. you really need to get voltage specific tests and report back with your voltages, it is possible to be in the wiring, esp. the grounds.

onefastrx712a

iTrader: (1)

Thanks for the fast reply... I will definitely check that out and report back

jjwalker

And by the way, Don't even look at the voltmeter in the instrument cluster as it is a piece of ****. At 14.4v my voltmeter in the car says in between 14.4 and 12. At 13.6v it hovers just above 12v.

For whatever reason I missed that you replaced the alt. I imagine my test I illustrated above will just tell you your voltmeter is just garbage.

ericgrau

iTrader: (1)

Replacement alts can be bad too; it' quite common in fact. Can happen right away, in a few months, or any amount in between. I hope you kept the warranty paperwork. Any auto parts store will test your alternator and battery for free, and they're easy to remove and replace if they need to test it outside the car. And if the next one's bad or fails quickly, you replace it again. You can ask around for a good alternator shop to get better odds, but it's still not certain. Wherever you go make sure it's a close enough drive to make returns easy. Best of luck.

The dash voltmeter can be bad, or it could be fine. You can verify with your own multimeter.

rotarygod

iTrader: (1)

You need to look at more than voltage on a meter. It's amperage that counts. You've got all the signs of a bad grounding system. Definitely check the wiring. Start with these tests:

http://www.aa1car.com/library/charging_checks.htm

jjwalker

Based on ohms law, the effective resistance of a circuit times the current draw of the circuit will equal the voltage on that circuit. If he was having issues with high resistance grounds, he would see a voltage drop across the battery terminals, and that voltage drop would increase with load.

This is why I told him to test with low load idle and with all of the accessories on at idle. So yeah, he really only needs to test voltage.

HAILERS

Is the small plug attached to the back of the altenator?

Got a meter? If so, key ON, engine OFF and pull the small plug off the back of the alt. See if the
Black/White wire has power. Should. It's the alt regulators power.

See if the White/Black wire has power. Should. NOw reattach the small plug. Get a sewing needle and ***** the White/Black wire. Key to ON. Engine off. That wire should now show 1-3vdc if the alternator is good AND you saw batt voltage on it when you had the plug off in the paragraph above.

Just adding more to the above ideas.

I don't think Rossi could cut it in F1.........oops, wrong forum.