twinreds

Looks like my battery wants to die, so I am planning to change it. What would be the best quality battery that would just drop in the square without having to do anything else to hold it?
Thanks!

RDS928S

The Interstate battery drops right in- MTP-91
I just swapped one out for a friend.
NAPA sells interstate batteries. You can even order on line with NAPA then go pick it up locally.

Good Luck

IXLR8

The East Penn 648MF battery I installed is 100% identical to the Porsche Moll Kamina it replaced. The case color is the only difference.

IXLR8

Here are the specs for the East Penn 648MF battery:
70 Ah, 700 CCA, 875 CA, RC 120 minutes.
280 mm long, 175 mm wide, 191 mm high.

Here is a list of other possibilities in the group 48 and 91 size:

Gunter

Thanks for the list, Alex.

Do they all have the small hole for the venting hose on top?

AFAIK, all lead-acid batteries in the trunk need the venting capabilities.

My current one has the little hose.........................

Quadcammer

I have the mtp 91.

its a battery...works like it should, not much else you can ask.

IXLR8

I could not tell you with 100% certainty. Maybe the vent tube is a characteristic of the group 48 and 91 batteries. I'll have to check into that.

I topped up my battery last weekend and since I had all the caps off, I was able to confirm that the caps are sealed, in other words not vented as some are. I also noted that the quality of the East Penn caps are top notch; two seals on each cap with the feel of soft silicone rubber.

Also, the East Penn 648MF has the vent in the same location as the OEM Porsche Moll Kamina battery.

From what I remember seeing on this site, I believe the Interstate MTP-91 has the vent in the center of the long side. Maybe Quadcammer can confirm that.

For sure, and to the outside. I'm going to check where the end of that vent hose vents to in our 993 (unless someone has a pic). If there is any possibility of corrosion in that area, I'll stick the end of the vent hose in a small "vented" plastic bottle with a dash of baking soda in it.

Quadcammer

yup, center vented.

IXLR8

Günter, if you or anyone else can read German, you might want to check out the ADAC Batterietest 2010. Note, we can only get a couple of those tested, here.

Too bad we can't get the Moll M3plus here...or is that what our Porsche dealers sell.

The ADAC is what we have here as the AAA or CAA. Imagine an auto club that has their own rescue jets.

certz

+1 for East Penn. They make Car Quests batteries for the Porsche. I prefer the AGM, but the MF is good also.

BobbyT

Optima Red Top is a direct fit, with no venting required, and it won't puke and damage your trunk. Costco has them for a decent price, first three years of warranty is free replacement.

fullbooker

Interstate for me!
Phil

Gunter

Current 993 Battery: Davidson Armored Battery 48/91 with vent and spyglass.
The PO bought it before selling the car. No clue what quality it is but, since it is new, I'll keep it.

Re: Optima.
No saving in weight and costs more than lead-acid.
Have seen quite a few negative comments about Optima over the years and since I'm old school, I'll stick with lead-acid. Open the cells once a year and top up with destilled water if necessary.

Unfortunately, Porsche doesn't have enough room for the battery area to allow a plastic tray there for protection. So, I use some silver foil to make a crude one and sprinkle some baking soda on it.
In the old 911, I added a Volt meter under the dash and would like to find a way to do the same for the 993. Over-charging due to an Alternator or VR failure is usually the culprit for acid to boil over and a Volt meter would show that.

IXLR8

Owners often talk about their weight savings when using an Optima. Sure, if a smaller Optima is chosen, it will weigh less...just like a smaller lead acid motorcycle battery.

Looking at a group 78 Optima (close in dimensions to a 48 or 91) it is in line weight-wise with a regular battery.

I did that last weekend. Unfortunately, one cannot do that to an AGM or GEL, even though one would need to.

Gunter, I used a Battery Mat under my battery. You need to trim it and its a bit tight to get the battery under the fixed mounting plate, but that is helped by tilting the battery edge under it. I can't speak to its effectiveness; my batteries haven't leaked.



Yup! Also note that voltage is based on temperature; lower when hot, higher when cold.

Gunter

That Volt meter looks good.
How is it wired in?

Used "Search" but couldn't find any details.