o/t Advanced Auto parts

The battery has been going dead in My grand Cherokee for the last few weeks. I have not been able to get my charger to indicate it has a full charge when I tried to charge it. It will go dead in about 3 days if you just leave the Jeep sitting. So today I charged it for about an hour then drove it about 5 miles to AAP. The checked and said it was good just needed to be charged. I told the manager I had just charged it for about an drove it to town. He told me since it took 3 days for the battery to go down it would longer to charge because of the memory in the battery. I told him he was full of BS.I have never heard of memory in a car battery and can't find anything on the internet about it.

The advanced person is almost right, a fully dead battery needs more than an hour to be fully charged. 6 to 8 hours is more like it. There is no memory. A battery is an energy storage device, it can release a huge amount of energy at once and it takes a lot of energy to replenish it if greatly depleted.
Due to chemistry, each cell is over 2 volts at full charge, so a fully charged battery is 12.4 to 12.6 volts. When a battery reaches 12.0 volts, it is considered dead.
Even expensive electronic testers cannot test a dead battery. You need to charge your battery overnight and check for a charging malfunction or draw on the vehicle. Leave the battery disconnected from the vehicle when charging this time. Then in the morning reconnect, go straight to store for testing. They may be able to test alternator output too. If battery tests good, you'll have to double check vehicle. Disconnect battery for a few days if you don't use vehicle, and battery should stay fully charged if it is not bad. Try to have good attitude at store (hard to do I know) and hope that helps you get best help.

also remember that an alternator is not designed to recharge a fully discharged battery. They are merely a maintainer. The amp rating is intermittent duty and the components don't hold up well at full output except for brief bursts.

Now about that employee, making things up and using technical terms that are absolutely wrong is my pet peeve, especially when used showing off or to assert superiority. It's hard enough to teach the facts sometimes and what about someone that believes the bs because they don't know better? We had a training video about batteries where the narrator was talking about "acid gnomes" to explain surface charge; I decided forget this and have no respect for my company's training programs any longer.

warranties are getting tougher though, as many manufacturers are deciding not to reimburse stores for warranty costs paid to customers.

good luck
karl f

Karl f,
I just wanted to say that was probably the best and most polite reply I've seen in a long time. Very well said.
I have a 6 year old Wally World battery in one of my old cars. It had been sitting for at least 2 years in the garage when I recently decided to pull it out. Battery dead, so I hooked it to a 10 amp charger with auto cut off. Left it on for a week. Everytime I walked by I looked. Sometimes the fully charged light was on, sometime it wasn't. Finally I took it off and the old gal started up. Been starting for several weeks now every day and yes I put the charger away. I was surprised with that old of a battery, I guess you never know.

Acid gnomes, now that is too funny. Can't blame you, but remember those training films tend to be aimed at the simple minded in hopes a small percentage will stick!

My BIL indicated to me that he went to the Harley dealer for a new battery. His was still under warranty, so they connected to the battery(he removed it from the bike and took it in) and pulled codes!

Yes, the Harley batteries apparently have thier own diagnostic computers buried in them that indicate when sold/activated and record any faults that happen.

It was news to me! Even under prorated warranty, it was cheaper for him to buy an aftermarket battery from an independent shop.

the way to proceed here it first take the battery off the jeep, have it fully charged then do a load test on it, this will determine weather the battery is bad or the jeep has a draw in it somewhere, if the battery passes a load test AFTER being fully charged, then there is something drawing it down in the jeep, other than the usual clock, computer ect, thats a lot more tricky to find, usualy its something like a lite on in the glovebox with the glovebox door closed, real hard to see in the daylite,

If you have an amp meter on your charger the charging rate should drop off once the battery is charged. Take a hydrometer and check the specific gravity in each cell and see what your readings are. Should be around 1.260 and all cell readings should be close to one another. Remove the ground cable off the battery when its in the vehicle and then see if the battery goes dead from sitting. If it will start after 3 days of sitting you probably have a battery drain. If the battery is too weak to start you probably have a weak cell in your battery. Your hydrometer readings should show this. Hal

thanks for your help guys.

Do you know for sure that the battery is self discharging or is there a large current leak in your vehicle that is draining the battery? Try disconnecting the battery, after it's been fully charged, and see if the battery holds a full charge on it's own or self-discharges.

I went through the same thing with a NAPA battery that would not stay charged ever when it was diconnected. I finally offered to leave the battery with the dealer over a weekend and let them test it. They charged it up on Friday and when I came back on Monday they agreed it was bad and replaced the battery under warranty.

Good luck.

Agreed.....Kudo's Karl

Could be an isolation diode in the alternator has broken down.

A fully charged battery should read 13.2 volts, ideally.