MUSSBERGER

Picked the battery off the Interstate website by putting in all the info.
It says I need the MTP-H8. Ordered it from the wholesaler (we are a dealer).
I bring it home and take the old one out. Wow the new battery is a bit longer.No biggie since I see the extra hole in the tray.
There's a little corrosion on the tray so I take that out and clean that up.
Put the tray back in and go to install the new battery and low and behold there are no threads in the extra hole for the clamp bolt.
Hmmm. Do I modify the tray or get a shorter battery?
Since we are about to get dumped on by snow this weekend I guess have the whole weekend to think about it.

LlBr

Me? Snowed in? Modify the tray? Probably. Total guess work follows: Assuming the battery was somehow better or an equivalent to the shorter version: It would drive me crazy until I got a piece of threaded rod or welded a non-threaded rod to a cut-off bolt. There'd be a hook at the end of the rod to go into the battery tray hole. Of course there should be minimal play in this arrangement and the hook should be holding onto something substantial. Would keep my mind off the snow and work. I could pat myself on the back for avoiding more errands involving a battery return.

MUSSBERGER

I'm think'n weld a nut under the tray for the bolt or better yet just get the OEM size battery.

LlBr

Yeah. Get the OEM unit. If I took care of it myself this weekend by modification, next week I would start wondering what would happen to the battery in a crash. Plus, even though tacking a nut down there seems bulletproof, there's no good ethics in unnecessarily trying to jury-rig a really nice car.

Mike in CA

Another option is to go with an Optima battery. They last longer, give better performance, and are significantly lighter than standard lead acid batteries. You can buy aluminum billet adaptor plates for around $50, or you can do what I did on my 996 and have a plastics place fabricate a piece of thick plastic stock to the proper dimensions for about $10. Drill some holes in the plastic plate, bolt on the battery and install the whole thing in the car using the stock mounting hardware. Not as nice as the $1700 lithium ion Porsche battery, but an improvement in weight and performance over the standard replacements.

sjfehr

There are only 3 main battery manufacturers (Delphi, Exide and Johnson Controls); just about everything else is just a rebrand of one of these. Johnson makes Optima, Interstate, Kirkland, Die-Hard, Motorcraft, and a few others. Don't let the sticker on the side fool you!

When you use the computer/book for fitament, be aware that multiple size batteries will show as fitting your car, but the more expensive ones with bigger numbers are not necessarily better, just bigger- typically, the big cold cranking amps numbers come from larger plates and larger batteries; you may need a larger battery in cold climates as battery chemistry is hampered by the cold, but in warm climates, you might as well go with as small and light a battery as will fit. As much as the marketers would have you think otherwise, brand and manufacturer don't really matter much; they'll all start your car and last 3-5 years. I spend hundreds of thousands of dollars on high-end industrial batteries each year at work, but I buy my own car batteries at Wal-Mart (Johnson rebrand, just like Sears' DieHard) or whatever store happens to be the closest if I'm helping someone out. Cost me just $75 to replace the bat in my 986S (Wal-Mart), and it was a 100% perfect match and perfect fit for the OEM Porsche battery.

dallison28

i just replaced mine in my boxster. For $75 for A 3 yr free replacement it worked for me. The only thing i go to wally world for is the automotive cleaners. I couldn't see spending more for basically the same thing.

when i buy my 996 or 997 in the future i would do the same thing. Now replacement parts i go with oem.

Mike in CA

It may be true that the same company that makes the Optima makes other batteries as well, but the Optima spiral cell plate design is actually different from standard lead acid batteries. Even if one doesn't believe the claims about longer life, more consistent voltage, delivering peak amps faster, better vibration resistance, better performance in both heat and cold climates etc. etc. there is one sure thing in it's favor; it's about 9lbs lighter with equivilant performance. That alone makes it worthy of consideration, at least.

chrisk1200

I endend up getting an Interstate MTP-H8 and put a nut under the tray for the clamp bolt. Seems it will work just fine. I hate returning things.

jplanaux

My battery (I think) is going bad. It is dying prematurely - car is three years old. I let it drain down one time completely (I left key-in while parked in the garage). Now it is barely turning over.

I have decided to go with the Interstate MTP-H7 - only because of the identical foot print.

Thanks to all that posted previously ... on the multiple threads. You convinced me what battery to get in a few minutes and potentially saved me substantial money.

atlast911

I could really use some help!! I hardwired a CTEK battery charger/maintainer to the battery so it wouldn’t die as my 05 997 sat. I had to remove the cable from the terminals to hook it up and now I have a “PSM failure” and “PASM failure” on the car, which I read could be reset by driving the car and turning the wheel per the owner’s manual. However the car won’t start, it turns over but won’t run (like it’s not getting fuel), do you know what this problem is and how is it fixed? Really frustrated with my dreamcar right now. Thanks

docfink

...just went oem for a new battery at the dealer. Not cheap, but didn't know what the problem was to begin with...live and learn, I guess.

atlast911

So my Indy had to reprogram the computer and all is good, car starts, $240 plus the tow.

LexVan

Oouch. Hummmm, did you cycle the alarm system before taking to the indy? Car might have went into sleep mode?

gota911

Unfortunately, most batteries listed as applicable for the 911 are incorrect. Many are physically too long to fit properly in the tray.

I had that issue with my 996 when I had my battery replaced at Auto-zone. I told the guy the specified battery was the wrong size, e didn't believe me and took it out to the car. When-\ he saw that it was too long, he asked me "What battery number did you say it was?" I just smiled and told him which one.