LexVan

I know a lot of us run this battery in our 993s myself included. Has/does anyone as routine maintenance add distilled water to the battery every couple years? If so where? I think I only see one fill plug in about the exact same area as the center vent tube under the black code date warranty sticker. Only one? I was expecting 6-8 cell plugs. Do these ever need topping off? Thanks.

mike cap

They don't require topping off. Same battery I've used (Diehard) for 12 years of ownership. Never added distilled water and never even check it. Unless you have boil over event - in which case you'd replace the battery anyway as a precaution.

Ocean Blue C2S

FYI ...these Interstate batteries ( I just bought one today) are MAINTENANCE FREE.

the previous one lasted just 4 years!

Cheers,

Bert

mgianzero

Actually, the Interstate MPT-91 is not truly a "maintenance free" battery. Maintenance free batteries are of the AGM or gas gel type batteries. This battery is a standard lead acid battery.

The battery has two small lip areas that can be pried off with a flat screwdriver. There you will find a 3 cell cap on each side of the battery - just like we're used to seeing in older batteries. There you can check the water level and also the acid content with a standard hydrometer battery tester. Distilled water can be added if needed.

It is true that, for the most part, the newer wet lead-acid batteries do not tend to lose as much water as older type. But they can be serviced to check and possibly extend their life even further.

I am hoping Alex (IXLR8) will chime in on this as he is the expert who follows these threads.

IXLR8

Exactly!

I can't comment on that particular battery because I've never seen one in front of me.

But these so called "maintenance free" flat top batteries that have no caps usually have a strip with built-in caps, that can be removed.

And there is no such thing as a maintenance free battery...minimum maintenance maybe, but they all need periodic charging and some topping up.

Three more months to go and my battery will be going into its 15th year.

AOW162435

I just installed a new Interstate MTP-91 this week. I installed the previous MTP-91 8 years ago. I never touched the battery, but typically kept the car attached to a Porsche battery maintainer.

The car seemed slightly harder to start recently, so I replaced it 'just in case'.



Andreas

LexVan

Thanks everyone. Good info.

rlme36

Anyone using a battery may under their batteries? I'd like to but the fender side mount doesn't seem to have much room to accommodate the addl height it would add when wedging the battery back in.

Thanks

Rob

linen grey ghost

Yes, I installed this brand (NOCO p/n MC316) [noco-usa.com available from BATTERYMART.COM] (no endorsement given nor implied, just for info purposes) battery mat under my Duracell 48 battery; trimmed to extend about a half an inch beyond all four side of the battery bottom; and it fits well. No binding issues and it is black in color.

RedSled113

I just pulled out an MTP-91 from the C4S is just purchased a few weeks ago. It was over 11 years old and still ok. I replaced it with a new MTP-91 just to be safe. Don't forget about resetting your readiness codes by doing a few drive cycles if you are coming up for state inspection in the near future. That was fun!

CarreraX

I'm assuming you installed this in a 993?

linen grey ghost

Yes CarreraX,

Installed in a 1995 Carrera.