Hi All –

Okay, I admit it. I’m a complete moron when it comes to electrical stuff. Hoping somebody on here can help. I did a search on the internet, Ih8mud & the PBB, but now I’m more confused than ever.

I’ve currently got a 3-wire 65 amp alternator on my 350 in my cruiser. The alternator Batt wire goes to the big post on the starter, where the battery + cable connects to. At idle (about 750 rpm), my aftermarket amps gauge reads just about at 50 amps and my volts guage reads a bit over 12 volts. When I rev the engine to about 2000-2500 rpm’s, the volts go up to 13 & amps move up just a bit.

I just picked up a 135 amp “1-wire” alternator. This new alternator is supposed to “kick on” at about 1000 rpm’s. After I installed it, at 1k rpm’s the amp guage reads just under 50 amps and the volts gauge read under 12 volts, but when I rev the engine, then the volts go up to barely over 12 volts & amps go up to just over the 50 mark.

I’m confused. Shouldn’t the 135 amp alternator show increasing amps as rpm’s increase? Also, I’m thinking that the volts reading under 12 volts at idle is also a bad sign.

When I hooked up the 1-wire alternator, I left just the one wire going from the Batt post on the alternator to the starter big post & didn’t connect the 2-wire plug into the side of the alternator.

Did I get a lemon alternator, or is something wrong with the way that I have it wired?

Does the alternator need to be grounded to the frame? (Currently it's not)

Maybe I need a larger wire going from the alternator to the battery now that I've got more amps output from the alternator?

Maybe I should hook the alternator directly to the battery+ post instead of going to the big post on the starter?

Maybe I should just torch the damn thing & go have another beer...

Any help ??? :(

you just have it hooked-up wrong...check out the following link...
1 Wire Alternator (http://www.classictruckshop.com/one_wire.asp )....
Hope that helps! :D :D

Okay, so I'll try disconnecting the wire going from the alternator Bat post to the big post on the starter & instead run a big-ass wire from the alternator Bat post directly to the positive post on the Optima.

Sounds too simple, but I'll give it a shot.

I'll let y'all know how it goes tomorrow after I get home from work.

Thanks!

Originally posted by Junkyard
I’m confused. Shouldn’t the 135 amp alternator show increasing amps as rpm’s increase? Also, I’m thinking that the volts reading under 12 volts at idle is also a bad sign.


No. The amount of amps the alternator puts out varies with the load on the circuit, not the RPMs. That is because it has a regulator. If you have a 50 amp load, it puts out 50 amps. In fact after you start it the current usually drops as the battery is recharged after starting.

It should put out about 13-14 volts while the engine is running at greater than approx 600 RPM in order to charge the battery. How accurate is your volt meter?

You have it wired correctly, since it doesn't matter which end of the battery cable it goes to as long as the Batt wire goes to the battery. You need a wire that is big enough to handle 135A. 6Ga should do it.

Hey Junkyard,
It sounds like it is wired correct. BUT, with the large wire running from the alternator to the big stud on the battery, I dont see how your ammeter shows a charge at all (or ever did). On my 71 FJ I have disconnected the ammeter (the wires spliced together and soldered) because I put on a 120 amp custom alternator. The ammeter was only 30 amp (?) I installed a voltmeter to monitor the charging. YOU SHOULD WIRE THE MAIN STUD OF ALT TO STARTER WITH AT LEAST 8 GA WIRE, 6 GA WOULD BE BETTER.
The alternator will only put out enough amps to get the system to the charging voltage. The regulator sets the max charging voltage. If the system only needs 10 amps to maintain 14.5 V then that is all the alt will put out. Turn on your lights, heater, wipers, big a$$ stereo, etc. and it will put out more to keep the voltage steady. When/if the load you have on the system exceeds the capabilities of the alternator, then the voltage will start to drop.
Make sure your alternator belt is tight. I am installing the pulleys and 100 amp alt off a 87 suburban on my 327 (during my TBI conversion). It gives me the standard rotation fan with a 5 groove belt. Should reduce slippage. It was wired direct to the battery with 8 GA wire and a fuse link (factory). I am wiring it to the Starter on my truck. You should go to an auto electric shop to get fuse link wire the right size for your alternator.