dr bob

It takes a bit of modification to get any commonly-available AGM's to fit in the 928 battery well. The popular spiral-cell models are too tall (posts too high) plus you need to find a way to anchor it. There are always ways to make something work, but they often take more effort to modify than any gain that might be realized. Most cheaper AGM's lack the power needed for a street-driven car with accessories.

That said, I drove my Subaru "mountain car" for a year in Mammoth Lakes with a 33AH UPS battery living where the original group 24/74 with twice the capacity had been living. It was what I had available at the time, and I couldn't rightly carry the correct replacement on a commercial flight. It was replaced with the correct battery the next time I brought the car down the hill for annual service and care. Never missed a beat. That was a little low-compression four-cylinder turbo at 7000' altitude, so it wasn't too tough to crank. Car lived most of its life with me stuck in a heated hanger at the airport, waiting for a chance to haul my butt around on a few ski weekends every month between Thanksgiving and Memorial Day. If it wasn't for the inherent poverty, I would have been a ski bum...

Jim Devine

These AGM batteries are direct fit- this one is for an '86. Available at Carquest stores under their label.
East Penn / Deka has a good reputation.

http://www.remybattery.com/Deka-Inti...50C30495.aspx#

The battery is no place to skimp- no fun waiting for a jump.

danglerb

928 is a difficult starting car as it doesn't fire until a full revolution or so (I think).

OTOH one of those tiny dry cell or AGM batteries is what is inside most of the booster jump boxes, and as long as they have a recent charge and the battery in the 928 isn't dead and draining current, they seem to start a 928 just just fine.

In an all out wt reduction plan I think they are a reasonable option, but I would carry a jump box spare battery in normal driving along with it.

dr bob

The batteries in those little jump-start boxes are amazingly skimpy -- 17AH rated, and the little terminals on the battery itself don't look like they will take the starting current for long. But... I watched Roger and his crew start several 928's in an hour with one of those at OCIC in Texas a few summers ago. I'm just not on board with relying on a tiny battery for all daily duties.

I think Alan in Phoenix has one of those 17AH AGM's mounted in the right-front wheelhouse with an isolation setup. as a defense against the common heat-relayed failure of the standard-fitment battery in his GTS.

Jim-- Good find on the group 48 AGM. I'd hope that the local retail price might be less than the buck-fifty MSRP on the manufacturer's website. Looks like a good option. We have a few Car-Quest stores in Cali, nowhere near the number of Advanced, Pep-Boys, or Wal-Mart stores for warranty service in a pinch.

WallyP

This applies to batteries, along with all-too-many other things...

"Maintenance-Free" doesn't mean that it doesn't wear out - it just means that you can't do anything about it.

S4ordie

Jim, have you installed this battery in your 928? I purchased and expensive Optima battery for the Zyclamrot car that did not quite fit, despite more than hour's worth of discussion on the phone with their customer support organization. It was just, barely too tall. Greg Brown fabricated a good fix.

I'd love to drop an AGM into the Turquoise car, almost time for one. So if you or others have tried the battery you cite, I will buy one.

Thanks

Jim Devine

On this page, scroll down & click on "more details"
has all the dimensions, CCA etc. It's NOT a lightweight race battery-
Note the recessed posts, so no problems hitting the battery cover.

http://www.remybattery.com/Deka-Inti...50C30495.aspx#

More here:

http://www.remybattery.com/Assets/Re...Automotive.pdf

Haven't purchased one yet due to the car being
apart, but fully intend to.
I'm a believer in putting in the best you can get,
no start = no fun.

Jim Devine

Did some more research- Called East Penn
cust service

East Penn makes the AGM batteries for ORIELLY
AUTO. Gives us a lot more locations to get them.
ORIELLY has a 36 mo free warr & 84 mo pro- rate.
No better on the price, but here it is from ORIELLY'S
site:

http://www.oreillyauto.com/site/c/de...rd=agm+battery