I'm looking to replace my battery, and, surprisingly, I've gotten a little confused.
First off, realoem seems to list *several* different P/Ns for a 2002 M3 vert, with different specs (70 AH, 80AH).
Googled and found some forum posts claiming that convertibles actually take different batteries than the coupe for both size *and* vibration reasons.
So I phoned a local BMW dealership and asked if they know what battery my car needs. Parts guy looked up my VIN and said "uhhh there are four different ones, what's in your car now? just match it with that." But I responded that my current battery was installed by the last owner, who didn't really know what they were doing, and I'd like to figure out what actual battery my car needs. He put me on hold for a few minutes, came back and told me he has one for me for $335, and it's 92AH (which doesn't match any of the ones realoem listed?). He also told me it absolutely needs to be coded to the ECU to work, which I know to be false, so, I had no faith that he was recommending the right battery.
Interestingly, if you look in the Bentley repair manual (sec 541-1), it states: "BMW has designed a special convertible battery tray with link rods which serve to dampen body flexing and vibration. CAUTION - The E46 convertible requires a special battery which is designed for constant vibration. A battery not designed for this will fail much earlier."
So,
1) Does anyone know the exact size, CCA and AH specs I should be looking for here for my vert?
2) What of this special vibration resistant battery? I'm guessing 99% of people buy generic batteries, and that this doesn't actually matter. But interesting nonetheless? Anyone have any comments on this?
First off, realoem seems to list *several* different P/Ns for a 2002 M3 vert, with different specs (70 AH, 80AH).
Googled and found some forum posts claiming that convertibles actually take different batteries than the coupe for both size *and* vibration reasons.
So I phoned a local BMW dealership and asked if they know what battery my car needs. Parts guy looked up my VIN and said "uhhh there are four different ones, what's in your car now? just match it with that." But I responded that my current battery was installed by the last owner, who didn't really know what they were doing, and I'd like to figure out what actual battery my car needs. He put me on hold for a few minutes, came back and told me he has one for me for $335, and it's 92AH (which doesn't match any of the ones realoem listed?). He also told me it absolutely needs to be coded to the ECU to work, which I know to be false, so, I had no faith that he was recommending the right battery.
Interestingly, if you look in the Bentley repair manual (sec 541-1), it states: "BMW has designed a special convertible battery tray with link rods which serve to dampen body flexing and vibration. CAUTION - The E46 convertible requires a special battery which is designed for constant vibration. A battery not designed for this will fail much earlier."
So,
1) Does anyone know the exact size, CCA and AH specs I should be looking for here for my vert?
2) What of this special vibration resistant battery? I'm guessing 99% of people buy generic batteries, and that this doesn't actually matter. But interesting nonetheless? Anyone have any comments on this?
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