NickHolloman

I put an Autozone battery in the car last year some time and I noticed the other day when I drove it that cranking was slugglish. By the end of the day it was dead. (I was at my Barber and the conversation was basically "Nice Porsche! Thanks, wanna give me a push?")

If it's the battery, what are you guys running? I hear people discuss lightweight batteries but have never really looked into them. The car is currently driven usually once a week (I had a trickle charger but cant seem to locate it) so Id like a good battery that wont continually go flat on me. Id prefer not to spend hundreds and hundreds on a battery. Is there a good bang for the buck out there? My cheapo Autozone battery clearly wasnt.

Mbren1979

Interstate AGM MTX94R/H7

Its an AGM battery with a 36 month (3 year) FREE replacement warranty! NOT a prorated warranty!

Retail is $225.00 but they can be had for under $200

De Jeeper

U need to determine if the battery is not holding a charge or if the battery is not getting a charge. While the car is running u should see around 14-14.4v off the alternator and similar at the battery terminal. The wires from the alt to the starter r a know issue with these cars and yours may be bad.

Ahsai

I highly recommend the AGM from Bosch

peterp

I have an Interstate in mine that is 8 years old. I've been wanting to proactively replace it for a long time, but it still works great, even when the car sits idle for a week or two. I don't know which model it is, but I've always had good experiences with Interstate.

Has anybody done any weight comparisons for 996 batteries -- particularly the actual weight of AGM batteries versus lead acid?

DBJoe996

I got an H6 AGM battery from AutoZone to replace my 6 year old H6 DieHard AGM battery. Weighs a ton but I don't care about that. Works great. They are located within walking distance so I figure it is just a walk, swap and replace deal. I can live with that. There are like only 5 battery manufacturers anyway. Did some research. Duralast AGM to their specific specifications. And the sticker on it says "Made in Germany"....go figure.

ThatSalesGuy

I have been running the same Duralast for about 10 months as well. No issues at all, even in the Vegas heat, where batteries typically last between 1-2 years. It comes with a 3 yrs full replacement warranty, so I don't mind replacing it if needed.

I put the same battery in the gf's (ex now) in January as that's what it called for. No issues there either.

DreamCarrera

I've had the best luck with Interstate batteries in my various sports cars.

A single Interstate battery (not sure of the model) lasted me about 8 or 9 years in my 996. I've had a NAPA battery in my 996 (again, I'm not sure of the model number) for the last 3 years and it has been going strong. I typically keep a battery maintainer on the car when it sits for more than a couple of weeks, which is often during the winter months.

Porschetech3

The Varta DH Audi OEM battery (000-915-105-DH) (H7) is a good replacement battery, that looks factory and has the vent hook-up just like the Porsche battery. It's a German made battery that can only be gotten from Porsche/Audi dealership as they are not sold in the retail environment in the USA.

Although they are handled/distributed by Interstate (owned by Johnson Controls) they are a European company/manufacturer. We were using the DH Audi battery as a replacement battery for Porsche for the Porsche dry-storage battery because it cost was so much less and was a good quality OEM like battery. Our local Interstate distributor actually relabled the DH battery for us to sell retail and have the Interstate warranty instead of the "Audi warranty"..The Porsche dry-stored battery also had to be filled with electrolite then recharged before install (making a hazzard and time consuming process, although dry-storage makes for long "shelf life")..

We were very pleased with the Varta DH as a Porsche replacement for quality and longevity, but like all batteries not regularly used, they need to charged periodically to keep from early failure.

JimmyChooToo

I too have 5+ year old Interstate. I have a brand-new Optima AGM waiting and just sitting in my garage waiting for the Interstate to die. But it just refuses to die. The 996 starts right up after 3 weeks of sitting around with the alarm armed.

Battery Guy

There are only three manufacturers of car batteries in the US that fit our cars. Johnson Controls (sells to most Walmart stores, Autozone, Advance, Interstate, etc.), Exide and East Penn (other Walmart, O'Reilly's). There are a couple of specialty manufacturers and a couple of Korean manufacturers but you will likely not see one of those for sale unless you are shopping at Menards.

What I recommend is normally Interstate simply because they have a good nationwide warranty. Same with Advance Autoparts. Also if you go online, Advance normally has a 20% off coupon for a new customer - I used this in my diesel Jeep Grand Cherokee (same battery as our 996) and it saved me $40. The dealer batteries (I think) are East Penn - they have the OEM contract for BMW and MB for plants in the US.

But really, it does not make that much difference. If the OP's battery failed in a year, it should still be covered under warranty - I'm pretty sure that the H6 batteries have at least 24 month free replacement from most retailers.

AGM is fine, but probably not really necessary. Likely it will weight slightly more than a standard battery. There are lithium lightweight options but they would be very expensive - may make sense for a track car, but no benefit for a normal daily driver. If the car is occasional use, keep a trickle charger on it - batteries like to stay fully charged and do not do well if they are left in a partial state of charge for extended periods of time.
Daryll

NickHolloman

Awesome advice here guys. Forgive my ignorance, but whats AGM?

wyovino

AGM = Angry German Machine. or maybe Absorbed Glass Mat. I put one in my car about 3 years ago - the Bosch Platinum Series AGM Battery Group Size H7/L4/94R from Pep Boys. My car sits sometimes for 10 days or more and I've not had any problems, even being in the North East in a detached, unheated garage. Check the Pep Boys site. Sometimes they give a nice discount if you order online and then pick it up. The site might say it doesn't fit your car but it does.

Mine didn't come with a vent tube. I pulled off the one from the old battery and put it on the new one. I don't know if it's necessary.

Porschetech3

There are three main types of batteries "wet cell" "AGM" and "Gel Cell".

Wet Cell are your standard type battery with lead plates and electrolite in between. Most all nowadays are "sealed lead/acid" and VRLA (valve regulated lead/acid) and do not require to have anything "added" over time.

AGM are Absorbed Glass Matt (sponge), that have a sponge in between the lead plates to hold the electrolite. This helps a bit to keep from having flakes come off the lead plates and shorting the battery, but comes at a cost. Also is not good for very rough off-road as the sponge will actually rub the plates and cause wear.

Gell Cell are just like the name emplies, the electrolite in between the plates are in a gell form and can be mounted in any way (sideways ect), and are recommended for off-road rough terrain, but is also the most expensive of the three.

These are the three main types of lead/acid batteries, then of course you have the lithium-ion batteries, very powerfull, light weight, and expensive.

Battery Guy

The benefit to AGM is that it will provide higher CCA (Cold Cranking Amps) in the same size case. But the drawback is that there is less free electrolyte (acid) so the battery is much more sensitive to overcharge, and will not last as long if it is abused. Also a AGM battery is much more temperature sensitive - you would not want to put it under the hood of a car next to the engine, but in our Porsches no problem in the frunk. Gel would not typically be used in a starting application - only deep cycle. Standard flooded batteries or AGM will both work fine in our cars as long as the charging voltage is good (should be around 14.1 - 14.2 volts on charge).

AGM also costs more than standard flooded batteries but that cost differential is decreasing as all three main manufacturers are moving more towards AGM for new cars with stop-start. My BMW with stop-start came from the factory with an AGM battery - they perform much better in repeated start applications. The next new thing that you will see soon is EFB - enhanced flooded battery - that will work well for start-stop but will handle under-hood temperatures. Again, not necessary for a 996 but will be a less-expensive option than an AGM battery in the next year or two.
Daryll