Alternator question?

[BiggBrakefuelie]

I have an Alt that is about a year and a half old.Its really has never seemed strong enough even when it was new.As soon as I pop up my lights the Battery gauge goes from 13.5 to around 12.7 and the power windows are very slow.During the day the accessories work normally.
I saw in the Ecklers catalog the they had different levels available for 69-82.They showed some they were 61amps,70amps but the one that I would reallly like to try is a Chrome Alt they had that was 140amps.
Would this likely solve my problem or could there be another problem besides the Alt itself causes this.A short perhaps?The Alternator in the Vette now was purchased at Kragen Auto parts.A friend told me this was a bad choice.
Any insights?:confused

 

[Eric]

If the alternator has been performing this way since new but has never died (and taken your battery with it) then the problem is most likely the voltage regulator. This is an internal part of the alternator that is supposed to make sure that you're getting enough power regardless of the amount of accessories you are running. Getting a new atlernator will indeed fix this (at least it should) unless the next one has a bad voltage regulator also. As for going for the extra juice, I boosted the one on my old Vette from a 65 to 80 amp with no problem. The boost helped at idle speeds to maintain the amps. As for going as high as 140 amps, hopefully someone else can advise on that.

Good Luck!

 

[Hib Halverson]

It is possible that your "new" alternator is not putting out it's rated current.

It's also possible that you have a problem somewhere in your 23 year old electrical system that is causing resistance but the alternator is working as designed.

An '80 shouldn't need a 140-amp alternator. The stock, 10SI, provided the unit you have on the car now has the same output as stocker, should be sufficient.

Windows that go up slowly may not be an alternator problem. It might be a problem with the window tracks, rollers, regulators, the motors or even the window wiring.

Lastly, you didn't mention, when you observe voltage dropping from 13.5 to 12.7, if the engine does that at idle or at higher engine speeds. If that happens just at idle, especially in gear, I'd consider that pretty close to normal. When you run the engine at 2000 rpm with the lights on, what's the voltage?

 

[WB6HRO]

I've always used this testing proceedure for alternators.

1. At idle you should have a reading above 12 volts to 14.2 Volts depending on state of battery charge.

2. Run the engine at about 2,000 RPM to get full alternator output. Should be 13.8 to 14.2 Volts.

3. Now turn on everything electric on the car headlights, A/C, radio, etc.

4. Check voltage at 2,000 RPM again if it dropped more than about .6 Volts it's not keeping up with the load.

5. Then you check for bad diodes (there are 6 diodes) with one or two bad diodes it will have output but not full current capability. Assuming that the correct alternator is on the car.

6. Should you get readings over 14.5 volts replace the regulator, before you smoke all the electronics and wiring!

 

[VETTEX2]

This is a good tester for a quick check of the diodes. I got mine from Snap-on and have used it for 15+ years. It's quick and cheap. Every time I matched it against a "BIG " tester it's been right on. Here is a link.

http://buy1.snapon.com/catalog/pro_...&group_ID=1474&store=snapon-store&dir=catalog

 

[Chris Sanchez]

Hi there! I'm very new to this forum but have already gotten invaluable information just by reading through the posts so I'm glad to be able to kick something back. I notice you are in Citrus Heights. The best thing you can do with that Alt. is to take it up to Auburn to Boyle's Future Tech. Jeff Boyle has been there for about a hundred years (seems like) and after working for the local big NAPA parts house (initials BR) and several car dealerships I have come to the conclusion that you will get FAR more for your money by letting him go through your old alternator than by buying anything except brand new off the shelf. He is one of those "heads" that knows WHY it works and what it should do and he'll have you diagnosed and on your way in short order. Usually for much less than you'd pay for a "spray-can rebuilt". Don't take it out of the car just drive up there and see the guy. He is on Lockley Lane in Auburn and all the local old=timers swear by him. (including all my pilot buddies)
Good luck!
Chris

 

[BiggBrakefuelie]

Thanks everyone for the help.My Alt registers about 12.9-13.0 at 2000rpm with the headlights on.I only get slow Power windows and other accessories when the lights are on.Otherwise they seem to work fine.The heater will also bring down the volts,with lights on heater on high at idle my car will register at about 12.0 or less.
Chris thanks for the reference I may look that fellow up.