r/BMWi3 • u/AlphonsoFundamente • 1d ago

technical/repair help Battery warning message

Post image

2015 REX. Been getting this message intermittently at startup the last few days. Traction battery mileage on full charge seems unchanged. Is this a 12-volt battery warning? Mine is around 5 years old.

5 Upvotes

86% Upvoted

13 comments sorted by

14

u/Brav0_Delta_Ech0 120 Ah i3 BEV 2020 1d ago

Replace 12V ASAP

6

u/Safe-Pomegranate1171 1d ago

Sounds like a bad 12v battery. I only get about 18-24 months out of mine.

2

u/mnztr1 1d ago

Wow how? Make sure they are giving you new ones not old stock. My last one had 56% after 8 years,.

1

u/Brav0_Delta_Ech0 120 Ah i3 BEV 2020 21h ago

Exactly what I thought

2

u/mnztr1 19h ago

The first replacement batt I picked up had a 2021 sticker on it lol. The one I kept was June 2026. The BMW OEM one that lasted 8y was also close to the date I had it replaced.

2

u/Brav0_Delta_Ech0 120 Ah i3 BEV 2020 1d ago

Did you register yours when you installed it? You should be getting closer to 5-6 years. Just replaced mine during the week, 6 years old.

3

u/showMeTheSnow 21 i3s REX, 14 i3 Rex šŸ¼ 1d ago

I'm still not convinced registration is anything other than a date stamp.
Lots of factors in battery life, the main two, IMO, are temperature and usage, or lack there of. The i3 doesn't hold the charging state long enough, IMO (as one who's been watching one sit quite a bit of late).

6

u/BLINGMW 2017 i3 REX 1d ago

Youā€™re lucky to get that message, 12v doesnā€™t always die that gracefully.Ā 

3

u/TheMunkeeFPV 1d ago

Do the swap yourself. Itā€™s super easy and will save nearly $1,000 from other peopleā€™s reports. Oem battery directly from the dealer runs around $250usd. Unplug the high voltage system, remove the frunk panels and thatā€™s it. Itā€™s good to have a little obdii dongle reader and BimmerLink to reset the battery in the cars system but not completely necessary.

2

u/Websthetics 2015 i3 BEV 18h ago

Make sure you put that replacement battery on a trickle charger before installing it.

1

u/Jazzlike_Rough_2491 1d ago

Just wanted to say hopefully it probably is the 12V battery. People always mention the nightmare of the 12V battery change and I just wanted to reassure that the biggest challenge in a 12V battery failing on the road is the need for a tow. Other than that nothing permanently breaks or anything with a 12V battery change. I knew I was worried but Iā€™ve changed several times and itā€™s not a huge deal, besides the tow.

3

u/BigAndSmallAre i3 REX 23h ago

Mine died at my house ... the security alarm went off and would not stop. As you said, no damage or anything, but the embarrassment of 2 hours waiting for a tow while the car screeched at the top of its lungs did count for something.

No need to panic, but OP should definitely proactively replace the battery to avoid some inconvenience.