The Stovebolt Site Forums The Shop Area The Electrical Bay What are you all running for alternators?

What are you all running for alternators? I've burned through 2 of them since my rebuild and not sure why. Maybe too low of rpms or something. I have LMC truck dual headlights (halogen) on too, maybe they draw too much power. Would that ruin an alternator though?
Thinking about getting a powermaster and just being done with it, but not if that's just going to burn out too.

Ya gotta tell us what your working on.

1961 chevy c40 261
Mostly stock wiring and stock heater.
6 mo old battery
New cable from alternator to solenoid and new battery cables.
Both alternators were 75 amp, that's what the engine builder out on so that's what I put back on when it went out.
Is the heat too much for them?
The first one had many miles on it, like 4 or 500, the second one went out after 30 miles.
Although the first 500 miles were mostly during the day.
Lots of idling.
2nd alternator might not be totally out, but last night didn't seem to hardly be charging so we'll see this morning when I fire it up.
Is it kind of hard to find an alternator that charges enough with low rpm? Maybe the heater can't run while stopped.

First, an alternator either works or it doesn’t. No in between, either good or bad. To know you have to test them. Second, most alternators are made off shore so getting a defective one is not that far fetched. If yours tests bad find a starter/alternator shop and have it rebuilt. You will end up with a better product. If your doing an excessive amount of idle time you may have to upgrade your battery and go to a bigger alternator like the commercial guys do. JMO

One bad rectifier diode will cut an alternator's output to less than 1/3 of its rated capacity. It will still charge, and develop the right voltage, but two of the three phases cancel each other out so you're only charging the battery (or handling loads like headlights, heater fan, ignition, etc.) with one winding of the stator instead of all three, without enough current to meet the demand. For instance, a 55 amp alternator will drop to around 9-10 amps, maximum output. The battery has to make up the difference, and slowly discharges itself. The problem might not show up if the vehicle isn't run at night very often. One dead giveaway is a rattling noise and the alternator housing getting too hot to touch.

RUN- - - -do not walk away from a Powermaster- - - - -trying to put alternator windings in a housing that sort of resembles a generator is only good for show cars and others that spend most of their time on a trailer getting hauled to the next "show and shine".
Jerry

I see. Overnight I put the battery charger on, and it fired right up this morning. Idled for a while and ran and stuff, and seems to be working fine. Will probably have to just get the higher amp alternator.
I was only looking at the powermaster's standard looking alternator that is black, looks really nice, but maybe the internals aren't any better than the others and it's overpriced.
https://www.speedwaymotors.com/Powermaster-57297-GM-12SI-150-Amp-Smooth-Look-Alternator-Black,98639.html?sku=25557297&utm_matchtype=%7Bmatch_type%7D&msclkid=31bf64db51191164a31b07c426448b50&utm_source=bing&utm_medium=cpc&utm_campaign=SMI%20-%20Shopping%20(CSE)%20(Bing)&utm_term=1100309997740&utm_content=Powermaster%20(Mar12_2019)

Unless you're running a LOT of high current draw accessories, like a mega-watt sound system, or hydraulic pumps to run a lowrider, a 75 amp alternator should be able to power all the accessories and have plenty of amperage left over to keep the battery charged. The original 12 volt generator only had around a 35-40 amp capacity, so the alternator is capable of supplying around twice the current the original electrical system needed. Even with high output halogen headlights, electronic ignition, and air conditioning, it's doubtful that you'd have a continuous current demand of more than 75 amps. Any charging system has two functions- - - -provide current to power the lights, ignition, and accessories, and use its leftover current capacity to keep the battery charged. Once the surge current drawn from the battery by the starter is replenished, charging current usually drops to less than 10 amps, assuming the battery doesn't have a shorted cell. Any competent auto electrical shop will have test equipment to monitor the complete electrical system and give you an exact measurement of the current demand. Like the Sun Electric Company slogan they put on all their test equipment- - - -"We test, not guess!"
Jerry

#1. Save your receipts for parts purchased. Get a refund if part fails under warranty.
#2. Have your FLAPS hook up their alternator analyzer to you truck and check voltage and see how much current it is pulling.

Hm. Will have to have it tested.
I'm learning more and more throwing money at something doesn't make it magically disappear, unfortunately.

Chances are.......... you HAVE A BAD BATTERY, are wiring it up wrong, have a short somewhere, bad hot or ground connections, buying from a bad vendor.

Get a rebuilt Delco

1. It's not the Halogen lights.
2. Alternator has a regulator.
3. 63 or 75 is enough output unless you have a lot of accessories all at once.
4. The alternator has it's own cooling fan. It is a huge aluminum heat sink also being cooled by radiator fan and forward air flow over it. It's NOT over heating.
5. You don't give us the part number and vendor of the alternators that went "bad" ...........so we can't investigate.
6. You have provided no basis and no testing to be able to say "alternators are burning out". If all you know is the battery is dead....look at the battery, check the output of alternator at about 800-1000 RPM and note above comments by the members. Alternators are a "brushless" design using slip rings. Alternators have an exciter function and residual magnetism to start output right away at pretty low RPM.

I have not considered having a starter, alternator, generator or any dyno/motor rebuilt except by me (which is seldom) for a long time. Too cheap and easy to buy and have delivered to your door or get at a local FLAPS with lifetime warranty. To me, sending to a shop was necessary at a time long past. I consider it a DIY or buy.

While on vacation with the wife, the alternator in our 3 year old Subaru Outback died. I had no tools with me. I took the car to a Subaru dealership and the next day a Genuine Subaru alternator was installed. Back on the road and 50 miles later, the brand new Genuine Subaru alternator died. Back I go to the dealership and barely make it before closing time. The service manager said it would take a week to get another new Genuine Subaru alternator then he asked if I would settle for a NAPA rebuilt alternator that he could install the next day (well, doh!). By the time my car was fixed, vacation was over.

From what little I know, it is that parts, especially new cars and trucks, are made world wide. The difference in what you receive may be "Quality Control". You have to pay extra to have automotive part knowledgeable people inspect and monitor the output process from Asian manufacturing (sweat shops). In other words, catch the bad stuff before it gets shipped.

ACDelco has or had a class action lawsuit filed against them because they got caught. An outside box/package said "Made in America" but the product inside said "Made in China". Don't put your faith in trademark logos or names.

Back on the farm, if the alternators you buy from your FLAPS dies under warranty, take it back for replacement or credit. I guarantee you if everyone did this, the loss of profit for the FLAPS and manufacturers would help them try harder to get it right.