Re: Smoking Alternator
I bought the $140 rebuilt with a lifetime warranty from Autozone. They sell an aftermarket "all new" alternator for $165, but it wasn't in stock and it only has a 2 year warranty. It only took 20 minutes to replace, so if this one fails I can get a new one down the street and it's just another 20 minute job to install.
This is in my 17 year old son's Taurus. He drove it yesterday and today and the alternator is working fine. It's not getting hot enough to cause a fire like the last rebuilt that died after 1500 miles and 4 months. The windings are almost black and still stink with a nasty burned smell. I'll take old stinky back to Autozone tomorrow for my $32 core refund.
I did a few tests with the new alternator. The battery was 12.6 volts before starting. With the engine running, the battery reads 14.8 volts, which seems a tad high. I have a clamp type ammeter that reads DC (most only measure AC current). Right after starting, the current from the alternator output cable was 38 amps. After a few minutes, it dropped to 29 amps and stabilized. Right after starting, the charge current into the battery was about 14 amps. This dropped to about 9 amps. Is it normal for the battery to get about 9 amps of charging current continuously? This seems rather high just to keep the battery at full charge. That much charge current probably overcharges the battery. Maybe the regulator voltage is a little too high, or is 14.8 on the battery normal? I know that 12 volt lead-acid batteries in computer UPS units float charge at 13.8 to 14 volts. They say anything higher will just dry out the battery from outgassing and shorten it's life.
Also, I checked the current draw with the new alternator installed. I just connected my DMM leads from the neg post of the battery to the neg battery terminal lead. It still does the same thing. The car draws about 0.7 amps for a few seconds, then drops to about 0.4 amps for a few more seconds, then drops to about 0.18 amps and stays there. I know that the clock, etc. takes some power, but 0.18 amp seems like too much. The car doesn't have an alarm, everything is factory stock Taurus SE. That current means the car is always using slightly more than 2 watts of power just sitting there. That's probably why it wouldn't start after sitting for 4 days. I guess I'll try the old "pull one fuse at a time" trick to try to track down what is drawing the current.