From Al Stensby Fullerton Calif, 2007 328i Sports wagon, 30k miles Regarding "We Can't Change Our Own Batteries " in the February issue of Roundel: I have a 2007 328i Sports wagon I replaced the battery myself ($145 at O'reilly) last month and the only information I lost was the time on the clock. Even the radio presets were maintained I initially called the Dealer and got a quote of about $450 for them to do it because they would have to "reregister" the system after the installation. However the service rep said just go ahead and install the battery and if it didn't run right then they would perform the "reregisteration" as a separate charge. The only glitch I had was there is a gadget on top of the battery which I had to remove and I'm not sure what it is. It is part of the positive cabling and is held on top of the battery by a couple of spring clips. Once I figured out how to get it off the rest was easy. Also in a previous issue you had noted that an aftermarket battery migh not have a connection for th gases vent. The O'reilly battery has the same vent connection. I especially enjoy Tech Talk and The Hack Mechanic.
You should still have them "register" the battery - it's a process to characterize the battery so that the charging circuity can optimize the battery's lifetime. I believe that the thingy on top of the + terminal is part of the emergency/crash dis-connect.
The gadget is the battery disconnect in the event of a collision... it is going to generate a safety fault if it is not there. I would put it back. It has an explosive squib in it that disconnects the main cable so that a short during an accident won't result in a fire. It will probably cause a fail when you go to get your car inspected if it is removed. Chuck
tell me more.. Would that also stop power window function if you're under water, or stop phone/radio communication, power door locks?
If it is indeed the BST (battery safety terminal, "SBK" auf Deutsch), it grew into a monster between the E46 and the E9x lines. This "gadget" is a big red block, nearly six inches square, with several heavy-gauge cables attached. The E46 BST was not much bigger than my thumb. Regardless, it's safe to assume OP meant "remove and replace" because, trust me, you'd have to be as dense as tungsten to look at this thing and think, "naaah...that's probably not important." (Plus, you'd have unattached cables left over.) No, it only fires in a serious collision and cuts power to the engine compartment only. Power is still supplied to interior systems and exterior lights (e.g., to unlock the doors and activate the hazard flashers after a wreck).
and safety system as well... It also powers the safety system through the "bypass" connection which you probably no longer have since it is not screaming a safety fault at you... Think of what actually happens during an accident... You make contact with some object, some time passes (not much) and your head is moving towards the windshield... BANG - the seat belt immobilization system fires, BANG - The main airbag prevents your head from moving too far forward... the car is still moving and spinning out of control, some more time passes (not much either) and your car makes contact again. Your head moves towards the drivers side window, BANG the side impact system fires and saves your skull again... Starting to get the picture? Its a ballet of safety systems all firing at different times as they are needed... but no power, no operation. Faults can disable operation. That part can save your life... put it back!!!
Battery Replacement My apologies. When I said "removal: I meant disconnect. I wasn't going to remove and discard the BST device. I meant that it was not immediately evident how to get it off the top of the battery to get the battery out. I appreciated the explanation of what its purpose and function are Regarding matching the battery to the car, I can buy a lot of batteries for what I am saving. My warranty is out in June and so I am reverting to my more normal DIY mentality. I originally made this post because I couldn't figure out how to reply to a Roundel Tech article but now that I have looked at the forum, I am favorably impressed with the participation and quality of the participants.
Power memory tool We have a 2001 325ci E46 convertible with 40K and always use the trickle charger when it is in storage; about five months. Our battery has worked flawlessly for ten years, but realizing that we are on borrowed time, I started looking to replace the battery. When I read the February column on battery change problems, I called my BMW dealer and they said $200 for the battery and $100 for the installation plus tax. So I called our local techie and he said they use Interstate batteries (the website says $150) but they do nothing to prevent the code/radio resetting. I went on the Bavarian Auto site and purchased the Power Memory Tool for $10 which uses a 9 volt battery and plugs into the cigarette outlet to help with this. Anyone have any success with it?
Thanks for the info on the 9-volt power supply. Next time I have to buy something over the internet for the car I will look for one. I originally was replying to a tech talk article in Roundel where they said you had to go to the dealer to get the job don/. I was never able to contact them. BMWCCA doesn't have the best IT.
