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Battery swap on 2007 3.0i Roadster

Discussion in 'E85 Z4 (2002-2008)' started by tbdbitl, Nov 21, 2012.

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    tbdbitl

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    I had my 2007 3.0i roadster in for a checkup, and the local dealer checked the battery, and told me it failed a load test. His recommendation was a new battery, with a price in excess of $300. This is the 6th winter on the original battery, so the diagnosis sounds reasonable.

    The price seems high to me, and since there are two imported car shops in my town, including one that seems to like German (MB and BMW) I want to check them out. I also have a good guy who specializes in restoration work, primarily corvette, but seems to be up on most things.

    My question is what is involved in installing a new battery? I have seen talk about registering the new battery on some models, but have no idea what that entails. What should I be looking for, and what is a reasonable cost?

    I live in Connecticut, which will probably have some effect on the $$$$.


    Thanks in advance.
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    dschultz 07 Z4 M Coupe

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    Can't help with the swapping process, although I'm interested in that, too. My experience with replacement BMW batteries in the past has been that they are awful. Perhaps they've improved recently but they're still over-priced. I've had good experiences with Interstate batteries.
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    MGarrison

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    Your model may well fall into the range that require the battery registration process - I think there's more in-depth discussion elsewhere here on the forums (use the forum search button to search "battery" or "battery registration"). BMW has apparently engineered the car's electrical and electronic systems such that they need to be closely attuned to the power supply of the battery, and the registration process is a diagnostic procedure the dealer must do to 'sync', in a fashion, the battery and the car. From what I've read, it sounds important to do or there's the risk of the system over or under-charging the battery, with a host of potential resultant problems, stuff like substantially shortened battery life, thought I'd read something someplace about a battery exploding, too. It may be that you don't have to use exclusively a BMW battery, but I believe it sounds like any correct replacement battery will need the battery registration procedure, if your model is one requiring it.

    It would seem with the relatively recent crop of bimmers n' batteries, we ain't in Kansas anymore, Toto.
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    dschultz 07 Z4 M Coupe

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    Doesn't it seem like having to "sync" a battery to the car is going a little far? Next thing you know batteries will have custom circuitry in them to ensure you *have* to buy batteries from bmw. Ok, Ok, I'm crawling back under my rock now.
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    MGarrison

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    Future comment on replacing a modern BMW's battery: "Looks like the unserviceable ECU inside my BMW's battery went bad again after a couple of years, again. Well, I guess $2500.00 to replace the battery isn't so bad compared to the alternative; the car is designed to self-destruct if it senses that any maintenance work of any kind is attempted by anyone other than a dealer's mechanic while in a dealership service bay. Oh, sure, it's a bitch for a few people, but, hey, those drivers were warned, and, after all, BMW IS serious about who it's going to allow to touch their vehicles. It's a real drag for those folks who accidentally touch the automatic fuel filler flap when it malfunctions at the gas station though, they really need to iron-out that glitch. You'd think this type of approach would tend to negatively effect overall sales volume! At least for most models except the 7-series cars, anyway."
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    • Technical Service Advisor

    charlson89

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    On your the e85 you do not have to register the battery. E85 are on the same electrical platform as an e46. On modern BMW's you do since they use a smart charging system. Basically there is a sensor on the negative post of the battery called a IBS (intellegent battery sensor) that measure battery soc (state of charge), battery temperature. All that information in then sent to the DME (digital motor electronics) over the BSD (bit serial data) communication line. The DME then adjusts the alternator charging over the same BSD line. Over time as a battery ages it takes more and more to charge it, so when you replace the old battery with the new one and don't register the vehicle then the charging system will over charge the new battery killing it. When you register the battery the DME will alter the charging system down so as not to overcharge the new battery. Also if you replace the battery with a new one with a higher or lower CCA (cold cranking amps) or AH (amp hour) you will need to program the DME to allow proper charging of the new battery. The same if switching from a lead acid battery to a AGM (absorbant glass matt). BMW batteries are made by excide since your doesn't have to registered I would recommend you replace with an aftermarket one yourself and save a bunch of money.
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    Zedfor

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    You'll have to redo all your radio presets.
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    dschultz 07 Z4 M Coupe

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    Sorry to hijack this thread, but I just reread it and that phrase jumped out at me. As I read it I felt a distinct warping of the space-time continuum which left me a bit unsettled. Apparently to some (including charlson89) a "modern BMW" is anything newer than an E46 or E85/6. But wait, I have one of those and I consider it a very new BMW! By some standards I'm new to the BMW fold... I started with a '95 E36, new, so I consider a "modern BMW" to be E36 or newer. Those E30's are "classic" BMWs. I'll bet there are still a few around who consider an E30 a modern BMW and would start the clock on the 2002. I think it's safe to assume that no one would consider the Isetta modern -- including my Dad who owned (and rolled) one when he was first married. Anyway, the rift is closing, I'd better get back to normal time.
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    StewieZ4

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    I replaced my 2007 Z4 BMW battery with an Interstate. I live about 50 miles form a dealer, so it was easier. The air conditioning did not work after battery replacement, so the dealer had to do "something" that put everything back on line. The "something" cost $100 and was not covered by the warranty. Because I do not use the car in winter, I bought a Battery Tender Junior and keep it plugged in if I'm not using the car a lot. It works fine.

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