The 12V battery replacement is a challenge

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bwilson4web

bwilson4web

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Hi,

When the 12V battery that operates the computers fails, the car throws a bunch of scary 'drivetrain' messages and can turn on the alarm. But the $277 replacement from BMW is too expensive. I found a local, $136 Deka, ETX18L that with razor knife and Dremel tool can have the positive terminal modified to work. BMW really over-engineered in a bad way the 12V battery.

Having done it once, I would trim off the offending metal part of the brass terminal fitting. This keeps the battery in original condition yet avoids the BMW 'lip'.

Bob Wilson
 
bwilson4web said:
Hi,

When the 12V battery that operates the computers fails, the car throws a bunch of scary 'drivetrain' messages and can turn on the alarm. But the $277 replacement from BMW is too expensive. I found a local, $136 Deka, ETX18L that with razor knife and Dremel tool can have the positive terminal modified to work. BMW really over-engineered in a bad way the 12V battery.

Having done it once, I would trim off the offending metal part of the brass terminal fitting. This keeps the battery in original condition yet avoids the BMW 'lip'.

Bob Wilson
Click to expand...

Hi Bob,
Thanks for the info. Do you have any pics?
Regards,
Dave Loader


Sent from my iPhone using Inside EVs
 
Here are the batteries side-by-side:
upload_2022-11-14_14-53-30.webp

upload_2022-11-14_14-54-11.webp

Here it tried to open the space on the substitute battery terminal:
upload_2022-11-14_14-56-2.webp

Here is the original cable terminal. The fat part would not fit:
upload_2022-11-14_14-58-14.webp

So with a Dremil tool:
upload_2022-11-14_15-1-55.webp

View attachment 18924

Bob Wilson
 
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