coppercutlass

Ok so i got a nice new alternator from powermaster. 150 amp unit. They reccomend a lead directly to the battery no smaller than 6 gage. My question is the power lead that was used originally., will it have an ill effect if I dont connect it ?. I know that's the feed to the alternator power wise but does anything else feed off of it further back ? Or is it strictly a 12 v. Source. I ran a 1 wire for years with the stock gage lead but since this calls for a bigger wire is ok to just cap that original feed wire or does it need to go to the alternator ? Should i hook it up else where if it needs to be hooked up ?.

coldwar

It's completely true, a short, heavy lead connected directly to the battery is best and functionally correct, especially in consideration of the fact your new alternator is capable of producing more or less double the charging current compared to the original alternator. BUT....

Your original factory-harness charging lead circuit if original is connected alternator charging lug to battery lug on starter. Other Oldsmobiles might connect at horn relay-lug on drivers' fender, a few other much more rare alternator types also seen. This original lead is completely adequate except in the instance when you operate the vehicle driving with a dead battery, with the alternator now charging the dead battery in addition to providing operating power to whatever is running in the car at that moment. All of us have had a jump for a dead battery then drive the car home, sometimes at night with lights and everything else drawing additional power the alternator now is providing without a charged battery providing capacitance and ballast for the charging system. In that case with your new alternator now producing potentially ±100 amps without the belt slipping, then the original alternator lead becoming in use 'too small' for the current now drawn and produced, the result being this charging lead now subject to heating. Driving a car with a dead battery is a poor practice, it has always been hard on the charging system, shortening component life substantially.

So what does this mean - If you run a new short heavy lead to the battery as the alternator maker wants, then vehicle operating power under charge or even heavy charge back feeds through the battery lead to starter lug then on through the fuse panel and other direct leads (such as head lghts) to circuits, assuming all factory wiring. Since you have greatly increased alternator output capacity duty cycle considered, if you wish to keep it factory in appearance, then the charging lead to starter lug should get increased in consideration of the current potential. #6 sounds good but even with multi-strand wire of the correct type with rated insulation (in case of fire), would be large and obvious, even wrapped with tape in or along side the factory harness. Also, should it melt routed this way, the other wiring in the same harness will get damaged, as also might happen with a factory wire.

When guys started retrofitting junkyard internally regulated alternators on older GM cars sometimes factory equipped with 45a alternators, once in a while you might hear of or see under hood fires starting with now undersized charging wiring far beyond original capacity. Big sound systems, cooling fans, air conditioning, fog lights and ***** lights hung all over the car, cruising around at night with all the lights on. Not hard to imagine how this might happen.

So the short heavy wire directly to the battery is the workable expedient, factory appearance not considered.

coppercutlass

Thanks. I bought a 4 gage wire and run a u inch lead to the fender well where I have a 3/8 junction. My main battery lead feeds to this junction which is a 0 gage wire then another 0 gage wire goes to the starter. I use that junction to quickly disconnect my starter. Most of my electronics like electric fans and what not i have set up on GM style weather pack connectors. From the junction to the batter is a 16ninch 0 gage lead so the alternator should have ample supply. If I understand you correctly. There isn't any use for the stock voltage supply wire any longer unless i wanted the stock look which i don't. My fear was if that same supply wire fed anything else in the car or if it was just a voltage source for the ALT.

coldwar

Since I see your car doing a burnout in your avatar, another plus I forgot about with the short lead to battery is the ability to easily disconnect the alternator at the drag strip for a few more HP. Caution shorting and fire potential with the now loose wire under hood. I used to just pull the exciter wiring connector on older Gm alternators for the same result, with key off of course.

coppercutlass

I actually have a switch I want to install for the alternator. But yes the loose wire will get capped off and tucked into the wire loom.

dragline

Your ground is as critical if not more. Now's a good time to double check grounds also.

coppercutlass

Grounds are all good. Damn near everything we rewired and replaced about 4 years ago when i tore it apart for a repaint.

Schurkey

I'm terrified to consider what you would do with a "switch" on a 1-wire alternator.

coppercutlass

Well switch for laymans terms but actually a marine 150 amp breaker.

Schurkey

That's every bit as bad.

coppercutlass

Shouldnt be much of an issue for just the blast down the 1/4 mile. It's be done over and over by many racers.

Schurkey

Who put a switch into the FIELD circuit, to disable alternator output. Which means they're doing it to a three-wire alternator, almost certainly with an EXTERNAL voltage regulator. You know...1960's technology.

THIS guy wants to put a circuit breaker into a ONE-WIRE alternator that has no external field wire. The breaker will have to be on the OUTPUT WIRE. Which means, if the breaker ever open-circuits the output, the diodes are going to scream in pain from the gigantic voltage spike he's just created. Diode failure is likely. Insulation failure on rotor or stator...or both...is possible, as is failure of the internal voltage regulator.

Nothing good comes of opening the output of an alternator.