Trying to hook up an alternator to feed two red top optimas on my drag truck. Tried a oem one wire to begin with and soon as I hooked up the charge wire it would drag down the engine and alternator would squeal. Disconnected charge wire, eng ran normal and no alt. squeal. I assumed the alt was bad so I order an east coast #2002 and install it and get the same results. Anyone had this type problem? Any help is much appreciated!

First off this is my opinion and I’m sure there are people that will disagree. Alternators were designed to keep A battery charged as needed. Trying to keep 2 batteries charged is a strain and if you have very low batteries that’s worse.
Question, are your two batteries fully charged? If so you have another issue.
Maybe try unhooking one of the batteries and see what it does.

What Barney said. Hooking up a new alternator to a discharged or bad battery will kill the alternator. Fully charge the batteries individually then load test them, again individually. Once done recharge the batteries then try the alternator again. I use a normal three wire gm alternator with two optima red tops no problem.

sounds like a shorted wire between alt and battery connection,or as said before bad battery.it indicates a high load situation

Disconnect 1 battery and see what happens, then swap to just th other battery.

You might have a v-belt that is too narrow and rides too deep in the pulley, or a stretchy belt.

Might try a Goodyear Gatorback belt with a wider width.

Thanks guys, I tried the disconnecting of one battery and same results, also one battery barely started eng so the batteries are extremely low, charged overnight so we’ll see. Thanks!

Ditto on the high load on the alternator, I had to run the battery wire to the alternator through a maintained contact magnetic switching solenoid to a switch on the dash so I could shut the alternator off when I staged the car. It was like I had a jake brake on when the alternator was turned on. It helps a lot to keep the batteries up if you double up and have to hot lap.

quote:

Originally posted by rusty:
sounds like a shorted wire between alt and battery connection,or as said before bad battery.it indicates a high load situation

Agree with this - I have jump started many cars as have many others with stone dead batteries and upon starting removed the cables leaving the alternator to recover the battery - this all being done with no ill effects.

I would say you have a short somewhere and it is pulling immediately full amperage. The other thing is you need to make sure the squeel as mentioned is not a bad belt/tension.

Take the alternator to get checked - any autoparts store can check it with a load.

You disconnected one battery and it did the same thing....maybe you disconnected the good battery?! One bad battery will make two batteries look bad. Question, why two batteries if you have an alternator? IMO, unless you need the weight, you do more harm than good with a second battery (for my reason listed above). Also, how many amps is the alternator, what size cable do you have ran directly to the battery?

Thanks guys, ended up being a pulley ratio issue, crank pulley way too big, down sized to 4”pulley and seems normal. I agree one battery prob all that’s needed.