QuestionHi Dave, hope you can help. This car ate the battery, and using generalized knowledge of charging systems I determined the alternater was bad and replaced it. That did not fix the problem.
With the ignition switch in the off position, I disconnected the negitive side of the battery, put a meter from the neg. post to the lead and I see 12 VDC. If I pull the wires off of the alternater I see 0 VDC, which I thought indicated a faulty alternator. HELP! Thanks, Rich
AnswerRichard,
The best general check of an alternator, and charging system in general, is to check your battery voltage across the terminals with the battery connected as normal, but with the engine not running. Normally you should see straight battery voltage, around 12 volts. Start the engine and check it again. It should be above 13.5 volts but below 15 volts. Ideal being 13.8 to 14.2. This is all assuming your battery is close to full charge.
If you rev the engine and the voltage goes above 15 volts, then you have a Voltage Regulator problem. Does this car have an internal regulator, incorporated in the Alternator? I can't remember what year they changed them on the Fiat.
While the engine is idling, if you remove the negative terminal from the battery, does the engine die or keep running? If it dies, you may have a bad alternator. I say "MAY" have, because there are some other things that could cause it to die also.
I'm not sure what you mean by "Ate the battery". Overcharging can ruin the battery quicker than undercharging. With the alternator disconnected, the car will run until the battery goes dead. If the alternator is overcharging, I've seem them actually explode a battery.
Most electrical problems on these cars seem to be traced to a bad ground someplace. It's worse with the all computer controlled vehicles but I suggest you also check the bonding strap to the engine from the frame. If your voltmeter is also an ohm meter, check the case of the alternator to a good frame ground to see if it's close to zero resistance.
Don't hesitate to ask a follow up. It's a real challenge to try to fix things by remote control. :)
Dave Miller
Deltona, Florida
