Limited electricity after changing the 12v battery

Hi everyone,

I have a 2016 BMW i3 94AH. 12v battery died while the car is in garage. I called a non-BMW service who came and replaced the battery on the spot. There were no issues during the process. Now the strange thing is that main instrument cluster is like trying to boot. It's showing the BMW i3 logo but that's it. Lights, locks are not working either. Only thing that works fully is the hazard lights. The service doesn't know what to do. They said the battery is fully charged as it's a new one but that's something I want to double check. Can I do it myself? Any other suggestions? Thanks all.

Usually when the 12v dies, it causes the car to throw a bunch of codes. These need to be cleared. Many people in the past have had success simply plugging the car in (preferably L2 charger for some reason) and letting the car sit overnight so the computers can work things out. This does not always work, but when it does, it is like magic.

Other things to check are
Are the Terminal adapters secured tightly? (TORX 30 bolt or 5/32" allen wrench)
Are the Battery cables secured tightly to the Terminal Adapters? (10mm nut)
There is a Red Wire that is attached to the Positive Battery Cable with a spade connector. Sometimes people remove this when changing the battery and forget to put it back on.

Thanks for the tips. I have checked all cables which were correctly attached. I cannot charge my main battery as the charge lid doesn't open. I tried to open it with the emergency cable which broke while trying. I guess no other option than towing.

The service doesn't know what to do. They said the battery is fully charged as it's a new one but that's something I want to double check.

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Hello kaserdar, sorry to hear about your issues.

If you want to be sure that the 12V battery is fully charged it's best to buy a battery charger and do it yourself.

The folks that swapped in your new battery said it was "fully charged as it's a new one" but it's a mistake to assume any battery is fully-charged just because it's new. The battery they installed in your car could have been freshly made or it could have been made in 2021 and shipped to your service folk three weeks ago.

I'm not sure where you're located. CTEK https://smartercharger.com makes excellent chargers. They're based in Sweden but sell their products globally.

Deltran is based in Florida and their Battery Tender brand https://www.batterytender.com is a popular choice in the US.

In a pinch, a local auto parts shop should have a low-cost charger that you could buy to top up your battery.

Once you get your hands on a battery charger, disconnect your new 12V battery (following the instructions to isolate the high-voltage traction battery – search "change i3 12V battery" for results).

Charge your 12V battery when disconnected from your i3, reconnecting it once charged.