battery advice? or is it the alternator?

[Adam12]

I think that it does charge the battery but the way I was driving (through a neighborhood stop and go) it would take a long time to charge it. because when you put one on a charger overnight it is charged, so I would have to drive a long time for it to fully charge a dead battery right?

[Chevy Wrench]

No, your alt. will never fully charge a dead battery. If your alt. only puts out 100 amps, than thats all your battery will be charged. It cannot charge any more than 100 amps. ( if thats what the output of your alt. is) Its like having a hole at the bottom of a glass. You can pour water in it all day long, however, it will never get full because of the hole.

[A.P.]

Chevy Wrench
So your saying that the garage charger that I got will not charge no more than 10Amps sense its rate for that??? No matter how long I let it charge it will only charge 10Amps?

[71GMC_3/4T]

You *can* fully charge a 1000 CCA battery with a 1 amp trickle charger. It will take a while, but it can be done.

Your alternator *will* fully recharge your battery, even if you have a 1000 CCA battery and your alternator only puts out 65 Amps.

The main reason an alternator may not charge a battery is if the battery is way discharged or has a bad cell. In that case, the battery doesn't have enough voltage to excite the alternator to get it to start charging.

Ampacity of a battery is current x time. It's usually listed as Ampere-Hours. CCA is only how much it can punch for a limited amount of time, usually in seconds, and always cold, like 0 degrees F. If you take the Ampere-Hour rating of a battery, and charge it with x Amps for y Hours, you can fully charge it. As you approach full charge, you will have to change the voltage to keep the current constant.

You want fries with that?

[A.P.]

71GMC_3/4T
Now that I understand. Thanks.

A.P.

[ckhd]

I can agree with 71GMC_3/4T. If it worked where your 100 amp alt will only put 100 amps in the battery, then it also follows that a 10 amp battery charger will only put in 10 amps.

After all, my 65 amp alternator charges my burb battery ALL the way up. 65 amps couldn't even think about starting my 'burb. Heck, 100 amps wouldn't do more than make it click a little...

[krue]

Amps is a measure of current, not charge. Charge is measured in voltage. If the voltage is high and the current is low, it will charge, it just takes longer.

[luke1]

Originally Posted by 71GMC_3/4T

You *can* fully charge a 1000 CCA battery with a 1 amp trickle charger. It will take a while, but it can be done.

Your alternator *will* fully recharge your battery, even if you have a 1000 CCA battery and your alternator only puts out 65 Amps.

The main reason an alternator may not charge a battery is if the battery is way discharged or has a bad cell. In that case, the battery doesn't have enough voltage to excite the alternator to get it to start charging.

Ampacity of a battery is current x time. It's usually listed as Ampere-Hours. CCA is only how much it can punch for a limited amount of time, usually in seconds, and always cold, like 0 degrees F. If you take the Ampere-Hour rating of a battery, and charge it with x Amps for y Hours, you can fully charge it. As you approach full charge, you will have to change the voltage to keep the current constant.

You want fries with that?

Regarding: Your alternator *will* fully recharge your battery, and then, The main reason an alternator may not charge a battery is if the battery is way discharged or.........




I recently had to replace my alternator. When my battery when out, I thought first, it was a corroded terminal. I replaced the terminal but the battery would barely crank, then died down. I figured the corroded terminal had probably ruined my battery, so I purchased a new battery. Replaced the battery, and was able to make it home. Next day, I went to work, and since it was daylight, the only thing running was the air conditioner. Made it to work (15 miles away). That night, on my way back home from work, I noticed that when I started the vehicle, the dash lights seemed dimmer than usual. But after a while, they became brighter, then after a few seconds when dimmer again. I turned off the air conditioner when I noticed that it had become a pattern of dimming then brightening. While I was driving home (60-65mph) it continued to do this. When I was almost home, I needed to turn off all the lights completely because I felt the vehicle stalling. Thank God, I made it home. The new battery was dead. Removed the battery and charged it overnight on probably the cheapest 12 volt battery charger on the market. Next day needed to go to the store, round trip maybe 2 miles, cranked up the vehicle to get there, cranked up the vehicle to get back. Tried to crank it up again, but the battery was dead. Removed battery to charged it up again. Removed alternator, walked it up to a autozone (mile away) had it tested. The associate working there said that the alternator was charging. (?) Really confused now. Thinking maybe voltage regulator, but while pricing an alternator, was told that there is a internal voltage regulator on said alternator. Thinking now it may be the cables from the battery to alternator. Decided to replace alternator, and have it tested while alternator and battery are both on vehicle. The associate tested it, and said the alternator was charging to 13.5 volts while vehicle was running, then performed a surge test on the alternator drawing even more juice from the battery, and the alternator was able to comply and keep the battery at 13.5 volts. Really really confused now. This went on for about 5-7 minutes, then I asked him if I could turn on the radio, air conditioning, wipers, lights , anything that would draw power from the battery, he said, go for it, HOWEVER , just before I was able to do any of these functions, the alternator stopped charging just like that, went down to 11. something volts. He told me, I had a faulty alternator. YES! Since there was communication between the alternator and the battery, (because of the various readings), I knew it could not be the cables. I recommend this approach instead of removing the alternator, and having it tested by itself, at least in this manner, you can eliminate some other possibilities. Replaced the alternator, charged the battery for about 2 hours, started the vehicle, went back to autozone to check out the results. I got there, turned vehicle off, came back out with associate and tester, open hood, put key in ignition, and nothing, the battery was dead. Utterly confused. Ask associate to jump start vehicle, and he did. Vehicle started, then connected tester to vehicle battery. Battery at 8. something volts, which apparently was not enough to crank the engine, and voltage going down while engine running. After a while engine stopped. Associate said faulty (new) alternator. Possibility, I know, but I'm thinking (hoping) maybe a blown fuse. However all fuses seemed alright. Asked associate to fully charge the battery so I can make it back home as it is now dark, and I've had it for the day. Battery now fully charged, I start the vehicle, turn the lights on, and hope I can make it back home. Everything seemed okay, the dash lights were not dimming and I was able to make it home. Once in the driveway and secure, I turned on the radio, air conditioner, wipers, lights still on, any and everything that would draw power away from the battery, and the vehicle stayed on. Left it like this for a while, then turned everything off. Cranked it up and it started. The world made sense again. Sorry about the long write, however, here is my confusion, how come my new alternator (which turned out to be functioning)was not able to keep the vehicle running (during the test) if it charges the battery. I'm taking into consideration that I had only charged it for about 2 hours prior to taking it to be tested. However, it had enough charge to crank the engine and start the vehicle and get me there. But only after the battery was fully charged, was the alternator able to maintain the charge, (and while I know that it needs to be able to function as a charger to maintain the charge), the(running) engine, during the test, stalled after a short while. There must be a minimum voltage that a 12 volt battery has to be at to maintain a running engine, in order for the alternator to fully charge the battery. If it is out of this range, then it falls into the way discharged battery category, and cannot be fully charged because it does not have the minimum voltage to maintain a running engine. I guess my question is, what happened to the battery which had enough voltage to crank and start and keep the engine running all the way to autozone, then was unable to crank and start the vehicle five minutes later? The only thing that I can figure is that the alternator needs a certain amount of voltage from the battery, which it was not receiving due to the overload, to operate and perform its function of maintaining a charged battery.
Thank you in advance for your advise, as I have found your advice, and all other advise on this forum very useful.

[Longhorn Man]

Hey luke1...dude, this post is like, almost 3 years old.

[truckdude239]

wow pulled this one from the grave

[VetteVet]

Yeah you reckon they have solved this debate yet. LOL

[luke1]

Sorry folks, didn't realize how far behind the times, I was.

[Tynee]

At least we don't have to tell you to use the search function before you post. Welcome to the board.

[matthufham]

no problem luke. i pretty much forget things from 3 years ago so it's good to freshen up.

[MisterMan]

my truck was tha same way, chased the problem for 5 months.... come to find out batt was good, alt was bad, and my trucks name is now christine...... she's a eat'n battery's. after several min. of sitting, the lights willl turn on by themselves. she would drain the to nothing, and continue to drain until she reversed the polarity. !!!! the alt was orij!!!.... also replace your voltage regulator if ya got one.... 12 bucks!.... kragen has life time warrentees on their batterys... i visit em every month of so.. .... (joke joke)

remove the negitive if its gonna sit awhile......

--den