This weekend the battery in my 1999 BMW M3 finally gave out. I bought the car in late 2003, so I know it was at least nine years old and probably was original equipment.
The fact it lasted so long is testament to BMW quality a couple of car generations ago. When my car was new BMW batteries were made by a company called Varta, which made U-boat batteries during WWII. Unfortunately the company was bought by battery giant Johnson Controls in 2002. As a result BMW batteries are no longer any better than aftermarket, just more expensive.
I’ll probably never have another battery as long lasting, so I held off replacing. The two leading candidates for replacement were the Duralast 49-DL and the Interstate MTP-91. I went with the Interstate since my local shop Hollin Hall Automotive carried it and I could pick up right away.
I’m glad I can change the batteries in my cars. Newer BMWs have highly sophisticated electronics that require a trip to the dealer for a reset of the onboard computer when replacing. None of that inconvenient and expensive complexity on the E36.
The process was very easy. Two important things to remember are the vent hose extension and the battery code saver. Since the battery is enclosed in the trunk, there is a hose that vents gases out of the bottom of the car.
If the replacement battery has the vent hole in a different location than stock (like the MTP-91), you need an extension to reach the existing hose. Also, E36s lose all setting and memory, including radio function, when the battery is disconnected. This can be prevented by using an inexpensive plug in the cigarette lighter connected to a 9 volt battery.
I won’t get a decade out of the MTP-91, but I’m set for a few years and happy to be able to DIY it.
Old and New
New battery installed — see vent hose extension top left
Radio code tool
Chris, I did this same thing on my M3 and M5 but found batteries at Autozone rather than Interstate. Both fit without any issues. I did put down battery-mats to protect from any acid leakage, cheap protection. It is nice to still do this as DIY!
Chris … I did exactly what you did for a 2000 323 Ci but had one problem shortly after the install. One of the battery posts, forgot which one, would heat up to the point that you couldn’t touch it. Do you have any ideas, before I have it serviced, as to what the problem may be? Would appreciate your response.
Hi Jody, thanks for visiting and question. I don’t know why that would happen if things were fine before you replaced battery. Since every battery today is backed by full warranty, I’d recommend returning to where you purchased for exchange. See if a different battery fixes the problem. Start with simplest possible solution, before going service route. Also, do you know that’s the right battery for the car?
Hi Chris,
I also love my E36, 99 Silver convertible, M3 :-) So much so that we brought it to the UK when moving here for work. We’ve had to replace several things to comply with European regulations, especially the lights. Now time is starting to make a dent on my car and battery has finally given up after almost 110k miles.
So i’m quite curious, how has it been with your new battery?
Cheers!