DIY: Battery Replacement

[tonysbone]

There are two/three things you need to do this. First you need a Group 94r battery. I found mine at Autozone for $145 Some people say the group 48 battery is correct. Beware, these people are shape-shifters and will lead you down the path of destruction. :-) Seriously though, either battery works and fits in the E90.

Second, you need the Bavarian Technic tool. http://www.bavariantechnic.com/buy.aspx
It's $287 and it will allow you to reset the battery adaptation that is required by the E9X. This is a little bit more than having the battery reset at the dealer, but once you have this tool, you'll be able to read and reset all codes, including the secret ones you can't see in the OBC, you can reset all service intervals, you can take readings from components (alternator and battery voltage, for example) you can also turn on components in the car to test their function. So overall, it's slightly more expensive than just going to the dealer, but in the long run, it should save you hundreds, and it frees you from the grips of the dealer and their "reprogramming" scam.

Optional, but recommended, is the Bentley shop manual. It lays out the order of steps I'm including below, but with labeled pictures. You can't work on these cars if you don't have the right tools!

Taking the battery out is a bit of a bear...

Remove the protective metal bracket mounting
Remove the negative cable.
Remove the battery hold down bolt (to the rear of the battery), and the foam piece that goes with it.
Pop off the cap on top of the positive terminal with a screwdriver.
Remove the positive terminal.
Slide the battery to the rear of the car and remove the battery vent hose from the side of the battery facing the front of the car.

The battery is now disconnected from the car, but it's still trapped there by the bomb-looking apparatus (really called the rear power distribution panel)

The whole assembly is clipped onto the top of the battery, so use the screwdriver to pop the clips off from the lip running around the top of the battery.

The assembly is now separate from the battery, but might still be in the way of you getting the battery out. I had to remove some of the power leads from the distribution panel so things had enough slack to move out of the way of the battery. If you need to do this, just make sure you put everything back where it belongs!

With this jumble of wires clear, remove the battery. You'll probably need a friend here to move cables as you lift it out. Better yet, make them lift the battery!

Installation is the reverse of assembly. Be sure the battery vent is connected to the new battery, and the bottom of the hose still is connected to the plug in the bottom of the battery tray.

Once everything is reconnected, connect the Bavarian Technic tool with the car turned on, find the battery adaptation reset option, click the icon, and you are done!

The Bentley manual states you might need to reset the clock, radio, steering angle sensor, power window motors, sunroof, and compass, but all of those settings were retained when I replaced my battery, so hopefully you don't need to do them either. The steering angle sensor is reset with the Bavarian Technic tool, if needed, and the power windows, sunroof, and compass procedures are outlined in the Bentley manual.

Overall, it took about 30 minutes to replace the battery. If I were to do it again, it could probably be done in 20.

Have fun!

[mryakan]

Everyone, please keep comments in this thread limited to DIY clarifications/corrections/questions. Please do not use this thread to post opinions about whether this procedure is required or not, this is not the place and it pollutes the DIY. There are other regular threads for such discussions.
I will promptly remove any off topic comments and issue warnings/infractions, so I will not accept the "I did not know" excuse.
Thank you for your cooperation.

[mystreba]

Thanks for the detailed instructions - saved for future use

[Georgere]

Overall, it took about 30 minutes to replace the battery. If I were to do it again, it could probably be done in 20.

thanks a lot, tonysbone

it was very helpful. i followed the steps to the tee. took me about 55 minutes or more (what can I say I am a noob ). if i had to do it again, probably 25 minutes.

about BT tool, I did find an option to register the new battery, but there was no confirmation... how do I know I did it right? (this is another reason everything takes me more time the 1st time i do anything - i am trying to make sure I did it right, yeah carzy)

[tonysbone]

Unfortunately, there really is no confirmation with the BT tool. In the very lower left of the BT program, the status (sending, reading, etc) is indicated, but there is never any indication beyond that. You just have to trust the tool, I suppose.

[TeaRoy]

Love it. Thanks. Mryakan...please drop this in the DIY section once it's hung out here for a while, great for future reference. Thanks again.

[mryakan]

Love it. Thanks. Mryakan...please drop this in the DIY section once it's hung out here for a while, great for future reference. Thanks again.

Thanks to the OP, I really did nothing other than put it in its own thread.
I am hoping someone may be able to contribute some pics to add to this useful DIY.

If anyone has any pics they want to add, please PM me so I can reopen this thread.
Thanks

[62Lincoln]

Thanks! Bookmarked.

[fun2drive]

Good information. I had hoped my Carsoft v 8.2 would have the battery registration feature but it doesn't. It is almost worth the cost of $287.00 to buy the Bav Technic SW since a trip to the dealer will cost you a 1.7 hours of labor which now runs around 170 bucks or more.

Much appreciated and since my E93 is nearing 4 years a new battery is in my future.