Some interiour lights won't go off when closing the car.

[Bertone]

I am having a weird problem when turning off/closing the car (2017 94Ah BEV) with the key fob. I have the easy entry option.

Some of the internal lights: e-brake, hazard light and light knob, are still on after closing the car.
Even after 15 minutes, when the car should turn off everything automatically, those lights are still on.

I'm fearing my 12v battery will be discharged.
The 12v battery is the original one and 7 years old now.

Is this a known problem ?

Thanks for your help.

 

[Bertone]

Measured the voltage on the battery...only 12,0 V, so I guess the battery is slowly dying???

Perhaps the main voltage battery is trying to charge the 12v battery...Hence the interior lights are on, I.e. like when charging the main battery with the domestic charger and those lights are on ???

 

[robthebold]

I figured I could get away a few more days before replacing the battery when weird things showed up and I ended up walking the kid to school in the middle of January.

 

[EvanstonI3]

Measured the voltage on the battery...only 12,0 V, so I guess the battery is slowly dying???

Perhaps the main voltage battery is trying to charge the 12v battery...Hence the interior lights are on, I.e. like when charging the main battery with the domestic charger and those lights are on ???

YES! Change that Battery ASAP before you get stuck some place.
A dying 12v battery will self-discharge rapidly over time and will refuse to hold a charge. Once the voltage reaches 12.0 volts the car comes on to try to keep it alive by boosting it for exactly One Hour. This will repeat over and over until the car cannot keep up .

 

[Bertone]

Ok, so the interiour lights are on since the main battery tries to charge the small battery ???? Is that what's happening ?

 

[EvanstonI3]

Ok, so the interiour lights are on since the main battery tries to charge the small battery ???? Is that what's happening ?

I just said YES! Get off the Internet and get a Battery.
When the car's DC-DC converter is "ON" and charging the 12v battery, a by-product of that is the lamps being on that you noticed.
I have the same year car and MY 12v battery died in June 2022. I have a Bluetooth 12v monitor attached to it so I watched it slowly fail to hold a charge over 2 weeks.

Here is what it looks like when the car is sitting for 24 hours without being turned on or used with a 12v starting to Fail
(note the Voltage levels and the Spikes are where the car comes on for exactly One Hour all by itself):

This is what the same thing looks like a week later, again the car is just sitting over 24 hours:

After that, it gets even worse. I changed mine out before it failed completely

 

[Bertone]

Ok, then all is clear for me...i was a bit worried the "fault" could be due to another issue.

Many thanks for the excellent explanation...
I' will source a new battery from the dealership tomorrow.

I have the bimmertool for coding it to the car.

Many thanks for your support !!!!

 

[alohart]

Measured the voltage on the battery...only 12,0 V, so I guess the battery is slowly dying???

How were you able to measure the voltage of the 12 V battery? The HV system turns on when the doors, hatch, or frunk are unlocked or opened which would turn on the DC-DC converter to start charging the 12 V battery when its voltage is that low. This makes measuring the battery's voltage tricky. You'd need to leave the frunk open until the HV system shuts off automatically (could take up to 30 minutes). Otherwise, you'd be measuring the output voltage of the DC-DC converter, ~14.3 V.

Perhaps the main voltage battery is trying to charge the 12v battery...Hence the interior lights are on, I.e. like when charging the main battery with the domestic charger and those lights are on ???

Those small interiors lights can remain until the 12 V system turns off which usually occurs less than 20 minutes after the last event which could keep these lights on. I don't think that these lights remaining on indicates that the 12 V battery is being charged, but I'm not sure how all of this works.

 

[Bertone]

I know that the small battery had 12,0 v because I took it out if the car and measured the voltage.
Disconnected main battery via the switch in the trunk first for safety reasons.
In fact, it was a bit warm too...most likely due to the charging attempts by the main battery.

I noticed something was wrong since those interior lights did not go off even when the car had been closed for over an hour...

 

[EvanstonI3]

In fact, it was a bit warm too...most likely due to the charging attempts by the main battery.

That is a classic sign of a failed 12v battery. The car is trying to charge it, but it won't absorb the charge. The energy is converted to heat.

 

[Bertone]

I charged the 12v battery over night, just as an experiment....after charging, it showed 12,5 v but after a couple of hours it went back to 12,0 v...so definitively shot.....

I bought a new original battery at the BMW dealer...165 EUR...now it is charging..this afternoon I'll install it.

 

[808Pants]

Isn't there a less-cryptic signal of imminent 12V failure than this virtual reading of tea-leaves? I haven't gotten there yet, but would like to get a few days' warning if possible.

 

[robthebold]

Isn't there a less-cryptic signal of imminent 12V failure than this virtual reading of tea-leaves? I haven't gotten there yet, but would like to get a few days' warning if possible.

In the olden days, they had a sticker with peel-able dots to indicate installation month and year, so when you had to get a jump start you look at those and say: "Darn it, I shoulda replaced that already!"

 

[eNate]

In the olden days, they had a sticker with peel-able dots to indicate installation month and year, so when you had to get a jump start you look at those and say: "Darn it, I shoulda replaced that already!"

Ha! My last i3 battery – dealer installed right after purchase – lasted about a year and a half. (Maybe they peeled the wrong dots! )

 

[Bertone]

In my first i3, a warning message indicating that the battery was about to be kaput showed up in the idrive screen when turning on the car.
Do not remember the exact warning text...but it was clear that the battery needed replacement.

 

[Bertone]

New battery installed and coded.
Locked the car and waited a few minutes......Went back and checked that no interiour lights were on....all were off.

Problem solved !!!!

 

[jamagaw]

Isn't there a less-cryptic signal of imminent 12V failure than this virtual reading of tea-leaves? I haven't gotten there yet, but would like to get a few days' warning if possible.

Isn't there a less-cryptic signal of imminent 12V failure than this virtual reading of tea-leaves? I haven't gotten there yet, but would like to get a few days' warning if possible.

When my 12v battery was dying, there were all sorts of crazy symptoms which were misleading. For example every warning message that exists would display! So, I would say that anytime you see odd behaviour, suspect the battery!