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Now why didn't I think of that? What is the approx. diameter of an M14 bolt?

I used a M14 tap to thread the last hole in the battery tray plus enlarging the hole in the battery hold down bracket

That would be approx. 14 mm.

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  • 5 months later...

Another question to being this thread back to life. Does anyone know why when I search for a 2001 996 battery the results are for size 48, but when I search for a 2002 996 battery, the results are for size 94R? Will a size 48 fit a 996.2? They seem to be a little cheaper with a little less CCA's.

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If you look at the Porsche (PET) parts/price list there are only 2 batteries for the 996 series - one is 70 AH and the other is 80 AH. Both are size 48.

Either will fit both the early 996 as well as the 2002 and later cars.

If you park your car outside in the cold often I would suggest an 80 AH (or better) battery otherwise you might as well stick with the 70 AH battery.

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I bought the larger one, for my 2002 996 C2, I forget the number, but it had more CCA's than the 48, and it did fit, with some slight adjustments,funny, but it cost less as well ?

I still have not fixed my electrical problem, where after about 4 or 5 miles and the motor heats up the alternator goes from putting out about 13.6 to 13.8 volts which is good, to 13.1 or even 12.7 to 12.9 which is NOT good :cursing:

Really weird, and it's not the alternator, I believe it's the wiring from the battery to the alternator,hence I always carry my trusty "jump start" in the trunk. One of these days I'll find out what the real culprit is ? I've given up, time to go to a Porsche electrical specialist , or the over priced dealer :eek:

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I had a problem on my 2004 911 Targa (35K miles on it) that when the engine (or alternator) heated up enough after about 10 minutes of driving the alternator output dropped to 10v. Killed the battery while driving. The Porsche dealer had refused to believe there was a problem with the car that was causing the batteries to die until I took a picture of the voltage meter at 10v and showed it to them. The only solution was to replace the alternator. Also, as for the battery itself, I took it to a Firestone retail dealer and they installed a non-Porsche high CCA battery without any sizing problems - for $90! (The Porsche dealer was charging me $300 for a lower capacity "factory" battery.) The Firestone battery greatly improved battery life for me as I drive the car infrequently and the old OEM batteries kept dying.

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I had a situation where my alternator voltage would start out (cold engine/alternator) with a charging voltage of about 13.5 and droop to about 11.0 volts as the engine/alternator came up operator temperatures. Appearantly, voltage regulators have a heat related failure mode. The fix was (after eliminating battery, ground/power cables) replacing the voltage regulator. A voltage regulator costs about $20.00-25.00 and can be replaced easily.....once the alternator is removed from the car. I, in fact, didn't work on the alternator. I took it to a auto-electrical shop recommended by my dealer. The shop had a new voltage regulator and installed it and tested it; part and labor $85.00 + tax. Now my charging voltage is about 14.3 volts.

Bill

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Thanks Bill, but been there did that. Took mine to a very reputable place where they replaced the voltage regulator with a more updated version, bench tested all and all was fine. Got another brand new battery as well. Same issue, I'm beginning to think its corrosion/resistance in the wiring somewhere ? Again, voltage is is ok on start up, but after 5 or 6 miles it goes from a healthy cold start 13.7 or 13.8, to about 12.6 or 12.7 after warm up. This has been going on for years, its a mystery ? :cursing:

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Thanks Bill, but been there did that. Took mine to a very reputable place where they replaced the voltage regulator with a more updated version, bench tested all and all was fine. Got another brand new battery as well. Same issue, I'm beginning to think its corrosion/resistance in the wiring somewhere ? Again, voltage is is ok on start up, but after 5 or 6 miles it goes from a healthy cold start 13.7 or 13.8, to about 12.6 or 12.7 after warm up. This has been going on for years, its a mystery ? :cursing:

I would be running a voltage drop across the main cables (battery to ground, battery to starter, etc.) looking for signs of corrosion. This is a very common problem on the 996, to the point that Porsche released a TSB on the subject and new battery and starter cables assemblies with more corrosion resistant connections. Not a difficult or expensive fix, but it is time consuming due to how the cables are routed. Do a quick search here, this has been written up multiple times.

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  • 1 year later...

So, I read through this entire thread and decided I would get the $80 Bosch battery from Pep Boys.  Sadly, the price is now more than double :(  -->  http://www.pepboys.com/product/details/672432/01634/2000/PORSCHE/911%2520Series/0/6-3436%25203.4L%2520DOHC

 

I may still get it -- I care about originality, but would rather have an US-style battery, so Bosch seems like the most "correct" replacement for the original.   I think it was stated somewhere in the thread that the Bosch is also made by Johnson Controls.  I don't really know how the Bosch branded ones compare to other Johnson Controls brands, but I suspect that Johnson builds them to different specs for at least some of the brands.   The user ratings for Bosch at Pep Boys is pretty high, so it seems like a safe choice.  Does anybody know if the Bosch is available for less elsewhere?  (or has the price really doubled).

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