How does AutoZone charge a battery in an hr?

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There site says they can charge it in an hr or less.

"AutoZone can charge your battery for free while you wait.

You left the lights on in your car overnight, and your battery is dead. What should you do? Take your battery to AutoZone. We have a Duralast Fast Charger that can charge your battery for free while you wait. The fast charger charges 12-volt batteries in about 30 minutes. AutoZone also offers overnight battery charging for 6 or 12-volt lawn and garden, motorcycle and marine batteries."

The proper way to charge a battery is like 2A all night or several hrs on say 10A is aceptable if your in a hurry. Quick charging a battery, especially in 1/2 hr or so could damage it.

I wonder how they get away with this?
 
Simple, they charge it to 77% with high amps, just enough to start a car. The first 77% is quick, bulk charge, it is the absorption stage, that brings it to 100% that takes time.
 
I agree they do a slam charge that is not a complete %100 charge. I concur to charge at least 6-8hrs or so.

Good sales method to get people with a bad battery. By the way your battery is toast, especially after we jammed it with 100 amps......I mean when we charged it.
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Originally Posted By: Chris142
I wonder how many batteries blow up, leak or whatever while they are cooking them?


I would guess less than you would believe. Now I would be curious if that charging had an effect on battery life. Most people who probably take advantage of that are in a hurry to get somewhere.
 
A batteries internal resistance increases as its charge does. So at first it can take a charge fast with low heat production. Once it gets to a certain point the internal resistance is enough to case heat problems and slow the charge rate.
 
I worked deliveries on this dysfunctional island where the mechanic would unhook the alternator field wire, put the truck up on jackstands, get on his creeper, and take an eight hour nap "looking for that broken wire".

We didn't let that thug get away with it though, as we'd hook the charger up on "55A boost" then go cruising like nothing was ever wrong. This passive aggressive game, and battery, lasted longer than anyone would ever have expected.
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Originally Posted By: oilboy123
I agree they do a slam charge that is not a complete %100 charge. I concur to charge at least 6-8hrs or so.

Good sales method to get people with a bad battery. By the way your battery is toast, especially after we jammed it with 100 amps......I mean when we charged it.
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My battery died after they charged it in order to run it through their tester. People here said that I should have brought a replacement battery from them, but instead I went to Firestone. I guess I made the right decision.
 
If the battery croaks due to this, it was on it's way out.

The alternative is to jumpstart the car, and maybe the alternator will croak instead.
 
Sure, if you have the time. I suspect that someone who wants a battery charged in 1 hour probably doesn't want to wait for an 8-hour charge.
 
Originally Posted By: brianl703
If the battery croaks due to this, it was on it's way out.

The alternative is to jumpstart the car, and maybe the alternator will croak instead.


I agree. What is the difference between this quick charge and jumping a battery and letting the alternator throw a 100 amps at it besides working your alternator hard?
 
Originally Posted By: LT4 Vette
If the battery is 6 years or old I would buy a new one.


Yep...you're probably on borrowed time.
 
Originally Posted By: Jonny Z
Simple, they charge it to 77% with high amps, just enough to start a car. The first 77% is quick, bulk charge, it is the absorption stage, that brings it to 100% that takes time.

Sounds like how a Midtronics charger would work, but in a less forceful way. A GR-8 can analyse a battery, and if charging is needed it can pulse up to 20-50 amps to "wake" things up and charge at a constant rate, usually around 10 amps with periodical tests.
 
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