KrazyK

I think the battery in my car was way too small. It was only 650 CCA, didnt fill up the tray, and showed a little less than 12 volts with engine not running. I went to battery warehouse and got the biggest vented battery that would fit in the tray. I had to move the mount to the extreme end in the unthreaded drain hole and secured it with a nut on bottom. It barely fits but it cranks much faster. Note: I didnt over tighten the clamps. Unfortunately I let the battery guy do that then I fixed the hold down mount myself. It looks worse than it really is because of camera angle.

Tomorrow I change the trans and front dif. oil. Yahoo!

kent

hi bro, i have changed my battery a few days ago, from your picture, why you did not connect the vent tube to the battery?

street rod

I put the most powerful recommended battery in mine. As kent mentioned make sure that vent tube is connected if you have not already.

KrazyK

Look on the side. Here is a better view.

MiamiC70

Damn, that thing is huge. "that's what she said" LOL.
Seriously, I just swapped my battery last week and it uses the first bolt hole to hold it. But I do agree with you it does seem small and the battery I just installed was installed under warranty as I bought the original one (Diehard) when I first got the car and it gave up the ghost after 2.5yrs. So, I do think that upping yo a larger battery is a good idea except for the extra weight

fpb111

https://rennlist.com/forums/996-foru...t-battery.html

I prefer AGM (Absorbed Glass Mat) Gel type batteries
I replaced an Interstate MTP-H7 With a Braille endurance series 7548 AGM battery - direct replacement.

Braille AGM B7548 battery group 48
BCI Group: [?]Group 48
Length:10.9" (277mm)
Width:6.8" (173mm)
Height (without posts):7.5" (191mm)

http://www.braillebattery.com/
http://www.braillebattery.com/index....durance_series

Battery sizes that fit 996 (group 49 will probably need a nut under the last, unthreaded, hole in the tray)

Group Interstate number Dimensions L x W x H Posts
48 MTP-H6 10-15/16 x 6-7/8 x 7-1/5 Top
94R MTP-H7 12-3/8 x 6-7/8 x 7-1/5 Top
49 MTP-H8 13-15/16 x 6-7/8 x 7-1/5 Top

perryinva

I put the larger vented Bosch battery in, same size, just fits. Like you said, starts faster, stronger, less worry about strain on the alternator or draining battery. Don't care a wit about a little extra weight. DO care a lot if the battery is dead after sitting for a month. I use a smart trickle charger all winter, too.

wwest

Size DOES NOT MATTER, REALLY....

With regard to terminal voltage anyway.

Even a smaller than factory standard battery will more than suffice provided it will accept, and is kept fully charged, or almost so.

wwest

"..less worry..."

The VR uses PWM, Pulse Width Modulation, to charge and maintain the battery terminal voltage at the proper level. A larger battery (more cell volume) will result in higher alternator peak power and a different, lower, operating frequency for the VR, thus changing the RFI/EMI "pattern".

Not sure if it matters, just saying.

Ubermensch

This is the first post I've ever seen bragging about increasing the weight of their car...Most people are going the other direction with batteries.

KrazyK

I was not concerned at all about the slight increase in weight. What concerned me much more was the capacity of the smaller battery. It was obvious the smaller battery was weak if you were in the car cleaning it or whatever and opening closing windows, roof, or using other accessories with the engine off. Also cranking speed seemed a little slow to me. These are high compression engines your trying to start. I dont drag race or track my car so weight simply was not an issue in the decision. I was under the car late last night cleaning the engine with an old tooth brush (and I enjoyed it) if that makes a difference in your critique of my Porsche dedication. My engine is now nice and clean.

function12

What you need to look at is the Cold Cranking Amps CCA. It looks like you went from a CCA650 to a CCA850. Sure it will crank faster because you have a whole lot more amps. You can still find a CCA850 in the smaller foot print.

wwest

Nominal terminal voltage for both will be EXACTLY the same. So it will only crank faster if there is a need for more current than a charged CCA650 battery can supply, which would be virtually NEVER.

KrazyK

Sorry WWest, I disagree. As I said in the first post, the voltage was less than 12 with engine not running. I suspected the old smaller battery was getting weak. Engine cranking speed much better now.

RF5BPilot

An enormous battery is a novel way to approach a near perfect 50/50 weight distribution in the car.

Good creativity.