[tumamilhem]

What is the correct battery size replacement for our cars? I was told by my local Porsche dealership that it was size group 48. I bought a size 48 but it is half an inch too tall and that side of the bonnet no longer closes all the way, but sits 1/2" higher than the fender.


What is the correct size replacement?


I bought the hightly recommended petformance battery Duracell Platinum AMG size 48 battery (Sam's only).

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[az968]

Interstate has a battery that fits perfectly. Check with an Interstate dealer and they can look it up.

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[968workaholic]

The newer style group 48 batteries do not work on the front engine cars, even the interstate batteries. The top was redesigned and it contacts the hood, but you already found that out

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[az968]

That's not good news. What group fits?

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[tumamilhem]

Group 42 fits, but it's an old size group (like the original group 91), so it's hard to find. But moreover, all group 42 I've seen don't have enough CCA. Factory CCA was 680/700. Most group 42 are around 500/550. So no bueno anyway.

 

The original factory size was group 91 (replacement group 48 is 1/2" taller, longer and wider than 91, thus too tall for our cars). Interstate has ONE group 91 battery available. It is a wet led battery (no AGM available in group 91 or 42 that I've seen from anybody). Duracell also have one group 91 battery, also a wet cell. This is basically all that's left for our cars unless you relocate the battery to the trunk. Here are links to both:

 

Interstate MTP-91 T6: https://www.interstatebatteries.com/products/mtp-91/t6

 

Duracell Ultra Gold SLI91T6M: https://www.batteriesplus.com/battery/ca...a/sli91t6m

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[WJH]

<p style="margin-left:40px;">Walmart Everstart Plus 41-4 

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[az968]

The Intestate I installed about 18 mos ago is a MPT 91/T6, Mega-Tron. No complaints, Fit fine.

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[ds968]

The Intestate I installed about 18 mos ago is a MPT 91/T6, Mega-Tron. No complaints, Fit fine.

Same here

That aside , I can't imagine we couldn't find a dozen different batteries which have sufficient CCAs that would fit in there - as long as the height is ok, you can find ways to adjust or retrofit the bracing to accommodate smaller width and depth batteries .

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[tejon007]

Bob, What happens to your "Intestate" battery when it dies?  (this one's for you Bill & yes, I know there's state statutes for descent and distribution...)

 

Optima battery:

 

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[MCL968]

Bob, What happens to your "Intestate" battery when it dies?  (this one's for you Bill & yes, I know there's state statutes for descent and distribution...)

 

Optima battery:

 

 

Well done John, took me a second to get your pun.

 

Seriously though, doesn't it upset the natural order to have a battery on its side? I like the quick disconnect on the ground wire, that makes winterizing a bit easier.

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[tejon007]

Matt,

 

I didn't want to leave you or anyone else out there that gets it - - actually, right after I closed my browser, I realized I should have included you too.

 

Where there's a will (yes, intentional), there's a way...the Optima won't fit except on its side.

 

Optima batteries can be mounted any way, even upside down.  I think they're worth the extra up-front investment because they last 2 to 3 times as long as "regular" batteries, require no maintenance, handle cold well, and have lots of cranking power.  I use them in all my cars.

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[az968]

I'll have to be careful of my typing with John all charged up Don't want to drain the energy out of this thread.

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[MCL968]

so, what size Optima works if you mount it on its side?

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[tejon007]

I haven't bought one for a while, but the last one was: Optima 8002-002-FFP RedTop Group 34 Starting Battery.  They're about $240, but come with 800 CCAs and are resistant to vibration...

 

 

 




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[tumamilhem]

I had an Optima in my 914. Didn't last too long. I have heard from others that they're not as good as they used to be. I went with the Duracell Ultra Gold. It's 1 of 2 batteries I found in group 91, the original size. They came highly rated on Consumer Reports and cost a $150.

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[paulzebo]

My Duracell Ultra Gold just failed after 13 months. No problem though, as it has a 36 month free replacement warranty. It was a no hassle exchange for a new one.

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[Ryan]

I don't know if any of you have "Rural King" stores, but you can buy batteries for $50-60 there. All their batteries are Exide which is one of the maybe four companies that make batteries for the market. I have one in each Porsche and they work fine. 

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[ds968]

My Interstate battery decided that it was the end its life today - I only realized now after looking at my records that it served me a faithful nine years ! Although for the last three years it was connected to a battery tender since the car has only been driven maybe one hour every two months, if even that ... Planning to replace it tomorrow with another Interstate, but hoping the same model / size / CCA power is still available . ( 91 , with 700 CCA ) .

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[pdxmike]

They should. I got a replacement in stock at the local Batteries Plus, Duracell brand, has been great for the past year. 

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[MCL968]

Ditto what Mike said, Batteries Plus has the 91 with the proper CCA. I just replaced my Interstate a little over a week ago. Funny, it gave no warning, I shut the car down, went into the store, came out a few minutes later and it would not start. Managed to push it back a couple of feet and roll it down the slope of the parking lot. Popped the clutch, drove it home, and replaced the battery the next day. Now that I have a new battery, I can see that the cranking speed had slowed down over the past couple of years and the car starts much faster with the new battery. Can't complain, the Interstate was almost 7 years old.

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