jyoteen

I did a bunch of searching on here and renntech and there seems to be confusion as to which is the proper battery. Some say Group 48 is ok, some say Group 49.

If you're going with something like Autozone, then for a 2003 C4s, Group 49 or the Autozone Duralast 94R-DLG is absolutely the right one.

You can fit group 48 which is a smaller battery in there and it works, but after 2.5 years, I think the battery was underpowered for day to day operation and the lack of proper sizing yielded its partial demise as I started to get fluctuation in voltage between 12 and 14v (13.6v) The car still fired up, but not the first time yesterday morning after sitting for 3 days.

On my drive of 15 miles yesterday, the voltage gauge was all over and turning on accessories made it fluctuate (especially using the HVAC system)

So, I went with the 94R-DLG Autozone Duralast. It fits with the securing bolt/hardware using the second bolt hole. I'd call it the 'medium' battery because a longer battery would (if existed) use the outside most bolt/hardware. Group 48 battery uses the 3rd inner hole.

Maybe I was just confused by the number of threads/confusion, so i'm adding my own layer of confusion for people.

The 94RDLG has the terminals in the right place, with vent holes on both sides of which the positive side venthole being used w/ the stock tube. Also, as far as power, it offers 740CCA and 140CA reserve which was better than the Group 48 that Autozone had. Interestingly, my Group 48 (installed by AAA had more CCA). Guy who was knowlegable at Autozone confirmed that my Group 48 was an undersized battery.

function12

Well I replaced my "Porsche" labeled battery with a group size 48 and it was an exact fit. So who knows.
FYI I have a 2004.

chsu74

There are adjustment holes to accommodate a larger battery. I used to have to fire up my car at least 10 days in between runs so my battery do not die. Then I found the drain last summer, aftermarket amp the PO had installed, and now I can hold 5 weeks before drives but it will barely crank.

jyoteen

Yes well, the 48 does fit, as does 49. It's not about the depth (front to back) because that is the same, but it's about the width. There are 3 holes in the battery tray to accomodate 3 widths. The 49 or the 94 DLG fits with the middle hole being utilized. I'm sure there is even a larger battery which fits the entire width of the battery tray itself and that too could be correct size. But 48, despite fitting and using the 3rd inner most hole is undersized as to the capacity of the battery.

I will test out my route today because I started to have PSM issues last month and there may be indication that the battery may be the culprit. This remains to be seen but battery sizing is more than physical dimensions. It's the overall ability for it to supply all the various electronic systems with the proper voltage.

Interestingly enough, the OEM Porsche battery which is long gone for my car is large dimension size and identical to the 94DLG. The Autozone battery was made in Spain so I wonder if the Moll one and the Autozone Duralast 94DLG is the Moll battery in disguise. There was also another larger Autozone battery which could have fit made in the Czech Republic which makes me wonder also.

LVDell

Well then I must have hit the lottery since the $45 size 47 generic Kirkland brand from Costco that we put in the CAB almost 6 years ago (March 2005) is still going strong. That's right, mine is even smaller than the 48! We only drive the car about once a week and keep it on a CTEK3300. Even has a 100 month warranty.

FYI...anything from 47-49 works.

ps. anybody else getting a battery ad at the top? gotta love Rennlist direct to user advertising.

C4CRNA

You sure your alternator/voltage regulator is OK?

jyoteen

yes, they checked the alternator and it's fine. The fluctuation dissapeared when the battery was changed out

function12

I drive mine everyday. It might sit one or two days during the weekend if I am hauling the family around in the Expy.
I replaced my battery about a month ago. My car car start turning over very slowly. New battery has been great so far. Just got back from a 300 mile day trip yesterday.

fpb111

I just replaced a good 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/index....durance_series


Interstate sizes that fit 2003 996
Group
Size Interstate Type CCA1 CA/
MCA2 RC3
(Min.) Warranty
(Months) Dimensions (inches)
L x W x H Posts

There are three holes in the battery tray they fit:

H6 (48) MTP-H6 640 800 121 85 10-15/16 x 6-7/8 x 7-1/5 Top
H7 (94R) MTP-H7 640 800 135 85 12-3/8 x 6-7/8 x 7-1/5 Top
H8 (49) MTP-H8 720 900 176 85 13-15/16 x 6-7/8 x 7-1/5 Top

82_930

Installed the Group 49 battery (Sears Diehard Advanced Gold AGM battery, 850 CCA)... it takes up the entire tray and the retainer attaches to the last hole (the one without the threaded pre-attached nut).

What I did to get around that was to take off the battery tray, put a stainless steel bolt with a star washer through the bottom of the hole so the bolt/star washer was upside down, and then re-installed the battery tray.

Next, I put in the battery and battery retainer and fastened it down with a stainless steel nut with a nylon insert (or lock nut).

The battery tray allows for a open ended wrench to be slid under to hold the bolt while you ratchet down the nut. You will have to remove the black panel that is next to the battery on the passenger side of the car (very simple, just one torx screw) to get your hand in there with the open ended wrench.

Perfect fit, and a 1-2-3 solution for the bolt hole!

fpb111

Good time to throw a cabin filter in there while the panel is out.

ryangambrill

What battery size fits the pre-threaded hole?

jdog

There are actually 3 sizes that fit I believe, maybe just two. I think they are a BCI 48 and BCI91.

fpb111

There are three holes in the battery tray they fit:

H6 (48) MTP-H6 10-15/16 x 6-7/8 x 7-1/5 Top
H7 (94R) MTP-H7 12-3/8 x 6-7/8 x 7-1/5 Top
H8 (49) MTP-H8 13-15/16 x 6-7/8 x 7-1/5 Top

The last one is not threaded. Porsche saved money on a threaded insert because you can put a nut and bolt through the clamp from the side of the tray on the largest one.

ryangambrill

Picked up a 48 AGM from Oreilly auto parts. No vent buy. Guess that is OK. Fits perfect.