Jumpstarting...can it kill alternator?

Walmart has a battery for your vehicle for $50.00. You could use a credit card if you have one and just add 50.00 to your next payment if you have a balance and you don’t have to wait 2 weeks.

I will let you know soon. Thanks.

I will have a friend to come over this weekend to check my alternator also but if it was the battery then why does it starts back up after an hour or so after it dies out?

You said battery is 7 years old. It has reached the end of it’s life span. Running down and recharging will finish it off and might take your alternator with it. Yes it could start the vehicle after setting a while but it could not have much left in it. Get a new battery.

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Ok, I will get a new battery, I was just concern on how come it showed the check battery light then when driving it dies out but if I wait a few moments it starts directly back up but thank you so much for your advise VOLVO_V70

My bet is on a faulty alternator. A 7 year old battery is definitely near the end of its life. but if AZ says they can charge it ok, and when they do it cranks the engine ok, the battery is at least marginally functional. No harm done to replace it, b/c like I say batteries rarely last more than 5-6 years on daily-use vehicles, but I’m guess you’ll still have an alternator problem once the battery is replace. If you know how to use a volt meter, you can do a simple check on the alternator very easily. Measure the voltage at the battery posts. For a reasonably well charged battery and the engine off, it should measure 12.4-12.7 volts. Now start the engine. With the engine running and a working alternator, It should now measure 13.5-15.5 volts. If it still measures 12.4-12.7 volts, the alternator isn’t charging the battery for some reason. And it is probably the jump start that did it. I damaged the alternator in my Corolla jump starting a neighbor’s car that had what I later discovered to be a severely run down battery.

WTH . . .

Sure, you can charge a 7 year old battery, and it might show 12.6V after you’re done charging it

But that certainly doesn’t mean it’s a good battery and won’t fall flat on its face at any time.

I still say the shop did OP a disservice by not just selling him a new battery. Don’t waste time attempting to charge a 7 year old battery. Must not be very good salesmen, either

Not disagreeing you at all db. Common sense says if it is 7 years old, buy a new battery before it conks out and won’t crank the car in the middle of nowhere. but if AZ was able to charge it, and it cranked the car, it’s not totally dead yet. I just replaced the battery in my truck. I noticed it was cranking slower and slower. Then one day it wouldn’t crank at all. I charged the battery overnight w/my battery charger. Still wouldn’t crank the engine. New battery cranks away like new. The age of the battery I replaced? 12 years.

With all due respect, are you perhaps missing my point

Just because autozone was able to charge it, doesn’t mean the battery is good, doesn’t mean it will hold a charge, and it may fall flat on its face at any time, without any kind of warning. In fact, I would count on it

The autozone salesguy should have said “Sir, I see your battery’s 7 years old. I don’t want to charge your battery, just to have it fail on you tomorrow, and then you’ll need a new battery, anyways, and you might have to call for a tow or a jumpstart. How about I save you that inconvenience, and I sell you a new battery right now?”

Because if the autozone guy does NOT do that, then mr. customer will have the battery charged. It’ll start the next morning, he and the wife will take a road trip, and they’ll stop for a bite to eat at some godforsaken diner, 50 miles from ANYTHING. No gas station, no repair shop anywhere nearby. And when they come out, the car won’t start.

That’s what’ll happen

And it all could have been prevented

Well, everyone, my friend who is a mechanic came over on Sunday and he ask me to start up the car, which started he then place a meter on my battery posts and determine that it is the Alternator because the battery is showing that its charged and that the Alternator is not holding any power so it’s not the battery so I guess I will have to get a Alternator. Also while the car is running he took off the positive battery cable and the car automatically shut off and he said if the alternator was good it should have kept running. I guess that (this is only my opinion) when I was jumping my truck and revved up the car when jumping my Escalade it somehow messed up my car Alternator or the alternator was just going bad, now I have to get some funds to try and get an alternator. Thank you everyone for your help in this matter.

Don’t ever disconnect the battery while the car is running!

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Well, I think George SanJose is correct everyone its the alternator.

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George SanJose, you are absolutely correct, my mechanic did what you are stating and its the alternator, I shouldn’t have and will never jump start another car, suv, truck or anything again.

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Two different people have reached a conclusion. Now we can we close this old thread .

Glad you are back on the road w a good charging system there OP. Good for you for sticking with it. You discovered the benefit of these forums, lots of good ideas offered to consider from. Just a matter of a few tests to determine which one it actually is. It’s good you didn’t just replace the battery and drive on, b/c a faulty alternator could stress your new battery and diminish its longevity. The advice above about refraining from running the engine with the battery disconnected is spot on, never a good idea, can cause electrical gremlins, which you don’t want.

With all due respect to your friend’s diagnosis . . .

You would be well advised to ALSO replace that 7 year old battery . . . ! . . . in spite of the fact your friend thinks the only problem is the alternator. That battery is on borrowed time, and this is not the time to be pinching pennies, just to get a little more use out of it.

Removing the battery cables with the engine operating is not advisable

Perhaps something was lost in translation, but that doesn’t really make sense

You don’t test batteries when the engine is running

And as far as an alternator 'not holding any power" . . . I couldn’t even begin to guess what your friend meant with that?

Again . . . I have seen plenty of situations where the alternator wouldn’t charge, because the battery itself was bad, and was the real problem. With a questionable battery, you shouldn’t count on the alternator to do its job properly. I have seen guys chasing their tails, replacing alternators, and the charging system still wouldn’t work properly, until they replaced the battery

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About a week ago I helped jump a car that wasnt starting with mine still running, for reasons best known to the lady turning the key she then absolutely floored the accelerator. From that moment on, my car needed to get jumped as it was no longer starting on its own. We checked the alternator & sure enough, the rectifier was fried and had to be replaced. Once we changed it, my car is starting perfectly again. Decided right then I wouldn’t jump anyone again and am investing in a jumpbox instead.

The exact same thing happened to my Corolla. Jumpstarted a neighbor’s car w/a very dead battery, which damaged the Corolla’s alternator diodes. The neighbor didn’t floor the pedal though. My solution, replaced the alternator. A few years later the neighbor asked me for a jump-start again. I told him I no longer do jump starts unless it is an extreme emergency, b/c of the prior incident. Instead I offered to drive him to a hardware store so he could purchase a battery charger. He said in a disgusted tone, “Whatever”, turned away and walked inside his house … lol …