dark knight

ama bit far from Porsche Dealer, have a dead battery, is there a good replacement, with vent to make it easy, Die Hard, Motorcraft, interstate are my main choices, I searched and it looked like the MTP-91 by interstate might fit but its about $200 and I read other people got it for $99 so maybe its not same battery-any thoughts?

Bob in NY

Interstate or Bosch are both acceptable. I can't imagine you'll get it for $99.I bought a Bosch for my 997 and it was about $250

trebien

Went to a "Batteries Plus" store yesterday to replace the battery in my 987.2 and it was $175 installed, branded as a Duracell with full 36 months warranty. The dealer quoted $511... insane.

digitalrurouni

I did the same in my M3 when the battery needed replacing after 4 years. Dealer wanted 800 and 2 days to keep the car and 'program' it and give me a loaner and diagnose the battery. WTF the battery was old needed replacement what diagnosis is needed? I did the same drove to Batteries Plus got the Duracell AGM for my M3 and installed it at an indie shop including programming the charging system for 90 bucks. 2 hours total including driving and getting installed. Battery was 180 bucks though. So 270 out of pocket. Still from 800 and 2 days down to 270 and 2 hours...I will take it!

trebien

I'll note one more thing about Batteries Plus, they also have a devise that plugs into the OBD port and provides power, as well as running 12V into the lighter plug... so the car never loses power and no resetting needed. Golden.

Their install fee? $5.

dark knight

ok, got the interstate MTP-91, its not an AGM battery, there is no vent hose in the Boxster, even with an AGM battery apparently the Porsche tester needs to read a Porsche battery serial number otherwise the alternator wont charge battery properly so its off to dealer

JCtx

I removed the battery on my new 2016 GTS to install a battery charger pigtail, and zero issues when reconnecting it. In fact, didn't even lose any memories (seat, radio, etc), which was surprising. Left battery disconnected for over a day, with nothing attached. Finally, most AGM batteries DO NOT need venting. The OEM does not have a vent. Just don't install a 'flooded' one, because any leak would be undetected being under a cover. Make sure it's an AGM (absorbed glass mat). The car doesn't have any freaking idea what brand of battery you're installing if it's the same kind as OEM. You shouldn't have any issues. Good luck.

dark knight

I was told there was a bar code number that had to be read into the computer or the alternator wouldn't communicate and overcharge the new battery and fry it

JCtx

That is really hard to believe. It's almost like saying you need to input the part number of an OEM oil filter or it wouldn't lubricate the engine. You can install any compatible battery you want. The only POSSIBLE caveat is if you remove a discharged battery and install a fully-charged one, some cars programmed to assume you changed the battery (probably ours) and throw a code that only a dealer can reset. Yes, they might have to reset it with a part number or something, but that doesn't mean the car knows what battery it has; just that you changed it. The alternator charges it until ECU detects it's fully charged, whether it was fully charged to begin with or not. I've never heard of any modern vehicle behaving like you mentioned above. Anyway, if you need to change the battery, and want to be extra careful, charge your bad battery before removing it (even when bad, it should fully charge unless it has several bad cells. It won't have much current, but should fully charge), turn ignition on then off. Your ECU will read your battery as full. Then you can remove it, fully charge your new battery (that alone can extend its life over a year), install it, and you shouldn't have any codes. But even if you did, your car should work perfectly, and a dealer can reset later on. A battery is a battery. As long as it has the same specs as stock, I doubt any dealer would give you grief. Remember I removed the battery on my car, actually charged it outside the car, and zero issues. Good luck man.