Y33 Alternator - HELP

[CJQ45]

I did something really stupid -- dont laugh please, I changed the battery on my 1997 Q45 (80k), and connected the terminal in the opposite direction. Well, other than seeing the 4th of July under the hood, I blew the 120Amp fuseable link. I changed the fuse and carefully connected the battery in the right direction. The car started.

I measured the alternator output - at start-up it reads 14.33 volts (winthin spec. range). As the car warms up to ideal - the reading drops to 13.85 volts. The reading doesnt seem to stabilize... it keeps dropping to about 13.33 volts after 30 minutes in ideal. Under a full load, AC, all lights, etc., the output in the worst case is about 12.86 volts.

I just started to pay attention to the alternator since I changed the battery - it may have been doing this all along -

whats going on..... Is this normal? The funny thing is that at startup it reads perfect output - 14.33????

CJ

[3Q Jay]

i assume the 12.8V is at idle? if you bring the revs up to 1500, does the voltage increase?

since you have a dvm, also look at the voltage when you trun the car OFF. if it goes from 12.8 up toward 13.2-13.5 or evn higher, then your alt is not up to snuff.

at least the alt is WAY easier to change on the fy33 than the G50....

[CJQ45]

Yes - the 12.8V is at idle with a FULL load - lights, AC, etc...

When the car is off - the volt reading is constant - 12.7 volts - it does not change.

What does the volt reading when the car is off tell you about the alternator... just curious.

[CJQ45]

Oh .... and the voltage does increase as I up to 2000 RPM. If the reading is 13.44 V in idle at 650 RPM.... the reading goes up to 13.50 volts at about 2000 RPM. However, it comes back down as the idle returns to 650 RPM

[FarFetched]

To truly test alternator you have to create load on the system .Observe Volts as well as Amp reading. You need a load tester with a carbon pile (or equivalent) to do it. With DVM you can only test V output which isn't for complete test.It looks to me that you fried voltage regulator. Bummer it is Go to a shop and test alternator output. All I know it should not exceed 15V at 1500-2000RPM. Test load goes till you get max lad reading on system - that would be Amp output of your alternator at idle or 1500-2000RPM.

[3Q Jay]

Yes - the 12.8V is at idle with a FULL load - lights, AC, etc...

When the car is off - the volt reading is constant - 12.7 volts - it does not change.

What does the volt reading when the car is off tell you about the alternator... just curious.

point being if the battery is supplementing the load, then turning the car off will remove that load and the battery voltage will recover.

a 0.06v increase is not enough at 1500 revs in this case, although it is an idicator that your alternator is not *completely* dead. my guess would also be voltage reg at this point.

my guess--only a guess-- is that you could probably nurse it for a week until you get a factory reman shipped to you from a sponsor.