that be it. after i showed mine to pete... he was all over it.. lol

 

The concern is about thermal runaway or overcharging to the point of overheating which feeds on the heat to increase the heat build up. I had an Optima which was flat and Autozone could not use their normal "quick charger" due to the POTENTIAL of melting or blowing up the case....

Ambient temperature greatly increases the risk as it reduces how much of a float charge is acceptable so there are many variables, just note it is possible with AGM batteries to have issues

 

when i worked at auto zone (manger) i saw that all the time when "optima/optima style gel cells" first came out. normal changing seemed to be ok. but when some one tried to use a standard batt charger/ tender it would kill the batteries ability to charge. i have an auto meter battery tender and it WILL NOT even attempt to trickle charge this battery.. at all. they have newer digital chargers that specifically do AGM and Gel cells now

 

My decade old Shumacher charger has an AGM setting, but I have no idea what it does, .... yet.

 

I have the Diehard group 48 AGM in my 928. I use the Schumacher charger with AGM setting and my wall-wart style Battery tender with good results. Both charge it fine

 

I have an Optima red top installed 3 years ago that was bought at Costco. It is kept alive via a "Battery Tender 800" from Pep Boys if I'm not gonna drive it for 4 or more days. No hiccups to report, however, recently I think due to the cold a few weeks ago (prior to putting her into hibernation) I could see the digital readings resetting whenever I started the car. That was my observation 3 years ago before the previous battery died. If I am correct AGMs last only 3 years which is expensive as batteries go. My Honda Ridgeline has the orig battery since 2006. My 2 cents

 

+1 here. I got one (advanced auto AGM H3 battery - FITS older/OB battery wells perfectly) from Jake's advice. Ran it all season. Loved it.

The AGM battery WITH the GM Delco Alternator swap are a nice complement to each other.

 

Those batteries are all made by the same company

Get the right size and just pick the Ah and reserve capacity you want.

 

Big Dave is correct. Johnson Controls make most of the car batteries sold in this country.

FWIW, I disconnect the batteries on my cars when I'm working, as I'll be out of state for 2 or 3 months at a time. I do leave my El Camino's battery connected, and it'll start right up. Just replaced the Wal Mart battery it had in it for the past 9 years. It still started the truck, but it ran like crap. Replaced the battery, and it runs like new again.

 

my AGM battery has been perfect for over 10 years now. 14lbs and has more than enough cranking power. its fully charged at 12.6v

BUT, dont run your stereo for more than an hour or two while you are waxing. remember, 14amp-hours only gives 14 amps for an hour .. .........

 

Anybody know if an H-6 will fit 89 S4/GT? The H-6 is 7.5 inches tall. The specified 40R is 6-7/8 inches tall. Eyeballing my current installation, 7.5 inches of height looks like it will rub the battery box lid.

I would like to possible install an AGM, but cannot seem to find any out there other than Sears in the under 7 inch range.

 

I have an Odyssey PC1700-A (AGM) in my '84. Snug fit but insulate + terminal from lid and good to go...

-tom

PS: Dimensions L x W x H (in): 13.02x6.62x6.93

 

I too am using an AGM in the Gold car similar to the one above "direct fit" no issues, purchased last summer.
On the Optima Yellow top, I thought there was a fitment issue (too tall)?