ew928

I'm not sure about the Optima.
Seen a famous 928'er with a few dead ones sitting in his garage.
He was not impressed by them at all. I haven't tried one. May stick with flooded plates.

The A/C seems to put a decent load on my alternator. When sitting in traffic in summer, the battery has to help the alternator (so no charging) at idle.
But the worst offender for sucking electric juice was my rear defroster.

Have my Passport radar detector set on voltage display mode and it gives a digital readout of what's coming out of cigarette lighter socket. I know I'm in trouble when I get to the low 12V range.
My alternator doesn't put out much juice at idle. Couple of hungry accessories in action and the alternator is crying for help.
Used to need a fresh battery around every 2 years till I started learning about the 928 electrical system.

Hilton

After a flattened din66 battery (audi, not 928) I couldn't charge with my cheapo trickle charger/maintainer, I ebayed my maintainer and bought a Ctek charger/maintainer/desulfator on recommendation from a 928 local who's in the battery business.

Impressed with the ctek - not cheap tho' but I'm expecting it to last.

dr bob

In my tool arsenal I have a plain old basic dumb 6amp charger, good for bringing over-discharged batteries back to life. Since getting the maintainer, I've used the dumb charger once in five years. As much as I like the technology that goes with the pulsing-rate sulfate looseners, I have to remind myself that the differenmce in battery life for me is four years vs maybe five years. At current local battery prices, I have a really tough time justifying the cost of the desulphator against the possible "$12 due four years from now" economy of just buying another battery when this one craps out.

The Duralast comes with a 72-month warranty to the original buyer. Pretty safe since most folks dump a car before it's two batteries old. I got a prorated adjustment on my last replacement that was about 30% of the shelf price. Took some negotiating to get it though, since by Autozone's testing machine definition the battery was 'still good'. Explained the specific gravity test and the store guy's eyes just glazed over. I sacrificed $1.50 to pull a tester right off his rack to show him how it worked, using my battery as a test dummy. Cha-ching, and a new battery was allowed.

RyanPerrella

Batteries have a shelf life, 3-4 years is about it.

Get it load tested at autozone for free, if its bad pick one up for $70 and it comes with a warranty for 6 years, you cant go wrong.

Larry928GTS

Anybody have any experience with one of these?

http://argusanalyzers.com/battery-mo.../bb-sbm12.html

Vlocity

I had the battery tested, it showed 615 CCA on a 650 CCA battery.

So looks like I will put it back in and give it a try.

Thanks to everyone who responded. I learned a few things.

Ken

dr bob

No direct experience, but it should work.

Back to my analysis though-- Another battery isn't much more than this gadget that tells you that you need another battery. Meanwhile, Porsche thoughtfully installed a voltmeter in the dash, indicating when the car is making adequate voltage to charge the battery.

The specific-gravity tester is typically less than $2, is absolute, easy to use, and gives you plenty of warning about your battery's failing health if used annually. No-brainer IMHO.

cold_beer839

My Optima also died a few weeks ago, and it wouldn't take a charge.
I called Optima about the warranty since it was bought only 2.5 years ago and I had the receipt, BUT they said according to the serial number is was 3 years and 1 month old, so they would not fully warranty it, only pro rate it and they even gave me the run around about that. Full replacement under warranty up to 3 years (but they go the date of manufacture not the date of sell). Needless to say, I will not buy another Optima for $200, so I bought a Durlast from AutoZone for $115. The Optima guy did say that if I connected another battery to the Optima with jumper cables, then connected the charger to the Optima, it might take a charge.

Benton

If you go with a lightweight battery, don't spend the coin on the Braille or whatever the other brand is. The Braille is just a rebranded motorcycle or ATV battery with a fancy CF cover on it. I purchased this battery: http://shop.advanceautoparts.com/pro...rtNumber=ETX14

I'm pretty sure it's the exact same battery as the Braille. Many other racers have been using it, and I've used it for the last 6 months. I use it with a cutoff switch and leave it disconnected, and have never once had a problem at all starting the car (I don't use a tender either).

dr bob

You can buy a U1 size battery from Wal-Mart. They are a little more than 30AH capacity and reasonable CCA when new. Guess-timating that they weigh somewhere between half and two-thirds of the original battery weight. U1 is a lawn tractor size, and that same size is often retrofitted to older personal watercraft to up the capacity over the 17AH size typically fitted. many newer/bigger boats come with this size as standard.

Earl Gillstrom

Some good battery info here but have to correct some numbers.

Dr Bob said "It usually rests somewhere around 12.2 to 12.5, so your 12.3 isn't something to worry about. If the voltage has dropped down to 12.2 or less after an hour of resting, it's time to go to the battery store."

This is not correct.

I assume these numbers are with no load. No load means that the battery is not connected to the car.

After a full charge, with the charger disconnected from the battery, the meter will read the surface charge of the battery which might be as high as 13 volts. After letting the battery sit a few hours a good reading is above 12.6 volts depending on battery type. Generally, anything below 12.6 is bad. 12.2 is a DEAD battery. 12.3 is a half dead battery. Most good batteries read 12.7 to 12.8 volts resting.