alohart
Posts: 2339
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Warranty replacement of 12 V battery

Thu Aug 09, 2018 11:05 am

EVBob wrote:suspecting something going on with the dc-dc converter or how the car maintains the 12v batteries.
You could insert an inexpensive 12 V voltmeter into the auxiliary power port below the center of the dashboard. It would clearly indicate when the DC-DC converter is on because the 12 V voltage would be ~14.3 V whereas when it is off, the voltage would drop to the mid to low 12 V range. This could prevent you from being stranded if you see that the 12 V system voltage is dropping below 12.0 V.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

EVBob
Posts: 151
Joined: Tue Apr 18, 2017 6:06 am

Re: Warranty replacement of 12 V battery

Thu Aug 09, 2018 11:31 am

Yep...time to get a pair of 12V voltmeters ....

though it was kinda easy to tell the 12v was failing when the center screen started flickering off while on the SOS call :x

jadnashuanh
Posts: 5196
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Warranty replacement of 12 V battery

Thu Aug 09, 2018 1:31 pm

The distributed computing system relies on a computer message to tell various modules to shut down when you turn the car off. If one or more of them is not getting the signal, it will discharge your battery. If the sensors are not reporting the actual voltage reading of the battery, it won't get charged. A static discharge test should show if the system is drawing excessive power when off. The clock, alarm, and remote entry systems don't use a huge amount of power, and the normal range of discharge is known...it's not that hard to measure, and should point to the problem. It's also not hard to test the DC-DC supply that provides the 12-vdc.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

EVBob
Posts: 151
Joined: Tue Apr 18, 2017 6:06 am

Re: Warranty replacement of 12 V battery

Tue Aug 14, 2018 8:59 am

Update on the "battery issue" - After telling them I wont take back the car with just a 12v battery swap (#3), they investigated further and found a power draw....they ordered a BDC to see if it will resolve the issue...hopefully it'll fix the issue...driving around a 7 series loaner feels like I'm going to hit something in the parking lot....that and having to visit the gas station ugh.....

Swede1
Posts: 3
Joined: Tue Oct 23, 2018 4:42 am

Re: Warranty replacement of 12 V battery

Tue Oct 23, 2018 6:07 am

How is it going Bob?
On my bmw service got new 12 v the battery and reproprammed as steering thing. (After searching fault for 10 hours and over 100 fault codes..., approx 2000$, gaurantee , not impressed by Segeltorp bmw)
;) I3 Rex 2015 Sweden Stockholm

Lynslee
Posts: 1
Joined: Fri Jul 05, 2019 9:44 am

Re: Warranty replacement of 12 V battery

Mon Apr 19, 2021 10:09 am

I purchased a CPO 2017 REx in 2019 and think there might be something going on with the 12v, but dealership says not covered under warranty?

Is there a difference in how i3s utilize this battery verses how ICE vehicles use their battery? Why are some dealers replacing these 12v batteries under warranty, but my dealer is not?

Thanks for any insights!

User avatar
MKH
Gold Member
Posts: 788
Joined: Fri Nov 02, 2018 5:48 am
Location: Dallas

Re: Warranty replacement of 12 V battery

Mon Apr 19, 2021 11:43 am

I purchased a CPO 2017 REx in 2019 and think there might be something going on with the 12v, but dealership says not covered under warranty?

Is there a difference in how i3s utilize this battery verses how ICE vehicles use their battery? Why are some dealers replacing these 12v batteries under warranty, but my dealer is not?
The CPO warranty doesn't cover as much as the factory warranty - and the 12v battery is considered a 'wear' item, not covered. Some dealers will replace them 'good will', most won't.

The 12v battery in the i3 is an Auxiliary battery. Unlike a12v starter battery in ICE cars designed to give a quick burst of power to turn over the engine, the AUX 12v is a deep-cycle battery there to power up the computer systems and electronics when you turn the car on, before switching to the DC/DC converter that draws power from the HV battery pack, and to provide power to the car's sensors, like the alarm sensors, comfort access sensors, etc. Like all batteries, they eventually age and fail. Some report them failing after three to four years, some have them last six or more.

Easy enough to replace the battery yourself - several YouTube videos show how. The OEM battery is manufactured by East Penn manufacturing, and they sell it as their AUX 18L, under both the Deka and Remy brand name. The Remy you can buy online https://www.remybattery.com/start-stop- ... ttery.html , the Deka you can pick up at any regional East Penn distribution warehouse. You can search for them here: https://www.eastpennmanufacturing.com/c ... re-to-buy/
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

Return to “Technical BMW i3 Discussions”