Dead new Battery, Faulty Alternator?

[django10000]

I just installed a new battery in my car about a month ago and now its dead. After charging and starting the car, I disconneted one of the battery terminals and the car shut off. Is it correcty to assume I need to replace the alternator at this point or could it be something else?

It seems pretty straightforward to change the alternator looking at the manual, any pointers the manual doesn't talk about and any ideas on why there are so many "amperages" available for my car and which one is correct? ...Just trying to learn.

As always, thanks for any help!

 

[minifridge1138]

Your problem could be 1 of 2 things.
1) you left something turned on (dome light or headlight) and they drained the battery while it was parked.
2) your alternator is dead and you drained the battery while you were driving.

Most parts stores can test an alternator and tell you if it is working.

As for why there are different amp ratings, I've read that the St. Louis factory had a habit of using whatever parts were available. Different alternators were used depending on what was in the factory that day. I'm sure someone here can provide more details.

Good Luck!

 

[Vettehead Mikey]

After you start the car, measure the voltage across the battery terminals. As you rev. the engine, the voltage should increase to 14+ volts. If it stays at around 12-13 then the battery is not receiving a charge from the alternator. Could be one of many of reasons why.

The requirement for different amperage ratings has to do with the potential electrical load coming from the acessories on the car. An AC equipped car usually has an alternator 15 or so amp bigger than non AC. Post the exact config of your car and someone can give you the correct part number.

 

[django10000]

Thanks for the feedback.

The car does not really have many electrical accessories, except the radio. There is no AC, pwr windows, anything esle. It is a 427 390 HP.

If I go with a higher amp rating, will it do damage to the car?

Thanks again guys

 

[22229stingray81]

I just installed a new alternator (try to get an AC Delco) on my '81, and I can tell you, yes it really is that easy. Try to get the tension on the belt pretty tight, with only around 1/2" of play. Sorry I can't answer you question about which alternator is right for your engine. Hope this helps.

-Tatortot

 

[minifridge1138]

My understanding is that an alternator with more amps will not hurt your car. Your electrical components only draw so many amps, and it won't hurt if your alternator produces more. You should be safe if you go to a parts store and order an alternator.

What would hurt would be if you added a lot of extra accessories (AC, pw, DVD player, etc) then your car would draw more amps from the alternator. BUT your wiring wouldn't be able to handle it and would over heat / catch fire.

 

[Vettehead Mikey]

The car does not really have many electrical accessories, except the radio. There is no AC, pwr windows, anything esle. It is a 427 390 HP.

If I go with a higher amp rating, will it do damage to the car?

In that case, the original part number was 1100833, 42 amps. Going to a higher amp rating won't hurt anything, but it won't help anything either.

 

[django10000]

I took minifridge's advice and took the car to and auto parts store to have it tested last night, seems like no charge is feeding back to the battery. I'll take out the alternator on Saturday and have them test that as well in one of the auto store's contraptions. I'm not quite sure yet, but the alternator may be original - if it is I may have it rebuilt at some point if it ends up being shot...does anyone have a clue as to who re-builds these things?

Also, not sure it it makes a big difference, but I forgot to mention that the radio is an upgrade from the original and it puts out about 200 watts (no amp is installed). If I decide to buy a new alternator, should I go a little higher on the amperage for this reason?

You guys are great help, I'm starting to learn some things - thanks!

 

[Curtis]

rebuild the alternator yourself..new parts are not that expensive. and is only a matter of changing out bearings, rectifier bridge and brushes.. Usually the stator is still good. take you maybe an hour and a half to take it off , fix it and install it.

 

[vigman]

A bigger Alt will NOT hurt anything

It has a regulator in it...the regulator controls the voltage (current would be the byproduct ) and your car will not go POOF with a 105 amp alternator vs a 42 amp... it's how much current it can DELIVER when NEEDED.

WHATEVER YOU DO! DO NOT BUY A PEPBOYS REBUILD!

the output insulators they use will not take the heat.. and melt.. like mine did. Causing a BIG SHORT and taking out some wiring.

I have an 80 amp alt in my 64 that works JUST PEACHY!

Vig~

 

[django10000]

Rebuilding it myself may be a project for a different time, I don't think I'm quite ready for that yet. I think I will go with a slightly higher amp rating and see what happens. Thanks

 

[LVMYVT76]

Take it somewhere that rebuilds them and have it done there.

 

[MikeMc71]

I went with a Chrome 100 amp alternator from Checker, its costs about $120. I needed the extra power for the electric fuel pump, fan, etc. I always had a problem keeping the thing charged before I got this thing.

Then after the new alternator, I bought an Optima red top battery, because the old battery kept going dead. I knew I had enough current to keep up with all the accessories, but the battery wouldn't hold the charge for some reason. Well, upon further investigation, I found that the new courtesy door switches I installed were not set right, and the interior lights would come on at the right temperature with the dors closed. I adjusted the switches, and cured the problem with the battery.

Sometimes the solutions are very simple, but as humans we tend to look for major problems that may not be there.

 

[ChuckG]

Rebuilding it myself may be a project for a different time, I don't think I'm quite ready for that yet. I think I will go with a slightly higher amp rating and see what happens. Thanks

John Pirkle in Georgia is "the man" when it comes to rebuilding and restoring original alternators.

When you get it back from Pirkle, it'll have dated diodes, etc.

If that's you bag, send it to Pirkle. If not, any competent electrical shop can rebuild it, AND when they rebuild it, they can make it any # of amps you want.

If it's the original alternator, do not turn it in for a core charge.

What are the numbers and dates stamped on the case?

69 alternators are as rare is chicken lips, and are extremely expensive to buy. Prices of $800.00 and up are common. They have a unique rear case.

They are "one year only", Corvette only, as that was the first year for the internal voltage regulator.

Up to 68, they used the external voltage regulator.

Chuck

 

[django10000]

I took the alternator out today, unfortunately not the original though - It didn't have the correct stampings, etc - so no chicken lips here, too bad. I turned it in for a remanufactured one at Andvanced Auto. The one I bought had a higher amp rating at 63 amps. You guys were right, very easy to install and I checked everything afterwards with a volt meter.

Thanks for all the advice.

 

[Evolution1980]

..and don't worry about your aftermarket radio with 200w. It's still not likely pulling any more than 10-15 amps at MAX power. You can tell by simply checking what you have it fused in to. Or it'll have an inline fuse.
You really don't have much electrical draw on your car, so the radio should be of little to no concern.

Regarding the tightness of the alternator belt, I use the "rule of thumb". That being that I can just barely push the pulley (.5" or so) by grabbing the alternator body and pushing the pulley by it's fins with my thumb.