HELP Please, Replacing 12v battery located under the frunk cargo tray

BMW i3 Forum

Help Support BMW i3 Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

effingnerd

New member
Joined
Aug 20, 2017
Messages
1
Does anyone know if there is anything special I need to do in order to replace the battery in the frunk? It appears to be dead and I was going to replace myself, however when I was purchasing the replacement, the parts employee told me that I shouldn't do it myself because the "something" to be disconnected before replacing it. He continued to state that it is not a straight replacement like the ICE vehicles, and that it would run me somewhere in $200 range to replace it, on top of the already $200 price tag of the battery. Any insight is greatly appreciated.
 
These are BMW's instructions for replacing the 12 V battery. Follow each link in the instructions.

De-energizing the high-voltage system might be "the 'something' to be disconnected" referred to by the parts person. It's easy to do following the instructions above, but ignoring this step could jeopardize the high-voltage system.

However, what's not possible to do is registering the new battery with one of the i3's computer modules if one doesn't have BMW's maintenance software. This is necessary to optimize charging of the new 12 V battery so that its life won't be shortened. I would think that any independent BMW shop could register the new battery for considerably less than a dealer would charge.
 
The Bimmercode app can do the required battery registration. FWIW, Pep Boys will do it for about $35, at least on some BMWs. There are OBD II devices that can do it, the Foxwell 510, also sold by ECSTuning as a Schwaben tool.
 
Bimmercode I do not think does this but Bimmerlink does they are different software downloads
 
I checked at Bimmercode.app and they say that you need Bimmerlink to 'register' a replacement battery ("Register battery replacement" button at the bottom of the Bimmerlink "Battery" page).

The Bimmercode app can only set the battery type. That is needed if you replace the factory AUX18L (20 Ah AGM) with a different size or style of battery:

Battery type

The type and capacity of the 12 V battery. Please note that this value must only be modified if the battery in the car has been replaced. After coding, the battery replacement has to be registered using “BimmerLink” additionally.

Values:
20 Ah
40 Ah
40 Ah AGM
46 Ah
55 Ah AGM
60 Ah AGM
70 Ah
70 Ah AGM
80 Ah
80 Ah AGM
90 Ah
90 Ah AGM
105 Ah AGM

Requirements:

“Body Domain Controller” BDC control unit
 
I think if you know the specific item, you can change it with Bimmercode in the expert mode. I did use a scan tool with BMW information in it to do that on another BMW...haven't needed to do mine on the i3 yet...maybe soon as it's getting old now, an early 2014, but not that many miles.

From what I remember, what you're doing is actually just a reset of the battery age that then increments from then on. The software looks at the age to determine how best to charge the battery.

Changing the battery type is a different item, but if you're not changing types, you don't need to tweak that parameter.
 
Back
Top