Unexpected Behavior: Car Still Powered After Disconnecting 12V Negative Terminal

[Geekice]

Hello,

I recently disconnected the negative terminal of the 12V battery to reset some control units, but unexpectedly, the car stayed powered.

I've attached a video to show the situation. Anyone had a similar experience?



Edit:A possible explanation I’m considering is that the traction battery might have been charging the 12V battery at that moment, keeping the system powered.

 

[siteguru]

The car should have been turned off (power off from the Safety tab on the Infotainment screen) before disconnecting the 12V battery.

 

[Geekice]

ed

The car should have been turned off (power off from the Safety tab on the Infotainment screen) before disconnecting the 12V battery.

yes, I first press power off from the FICM and then i disconnect the negative.

 

[webhiker]

FICM?

 

[Geekice]

FICM?

Front Infotaiment Control Module

 

[webhiker]

Better write it out loud, than creating your own acronyms. It'll give you a higher respons rate

 

[Kithmo]

It doesn't look disconnected to me. The cable is still on the battery terminal.

 

[Geekice]

It doesn't look disconnected to me. The cable is still on the battery terminal.

The cable is disconnected, the terminal it’s connected only with the Volt and Amperage sensor and then there is the negative cable.

 

[Everest]

Front Infotaiment Control Module

Ah... as opposed to the RICM, the "Rear Infotaiment Control Module"

 

[siteguru]

Better write it out loud, than creating your own acronyms. It'll give you a higher respons rate

There are loads of acronyms/initialisms when it comes to EVs. Should we also spell out Electric Vehicles too?

 

[wattmatters]

The cable is disconnected, the terminal it’s connected only with the Volt and Amperage sensor and then there is the negative cable.

Sure looks like it's still connected:

 

[Geekice]

Sure looks like it's still connected:

View attachment 34401

Yes, it’s disconnected.

 

[Martinonline]

Did you measure the voltage at the 12V battery to confirm your suspicions?

Usually, powering down the car switches off the 12V battery charging which is why I've noticed the infotainment display goes off after 10 minutes to avoid running down the battery. (I've needed to power up the car again to get my music back.)

 

[Geekice]

Did you measure the voltage at the 12v battery to confirm your suspicions?

Usually, powering down the car switches off the 12v battery charging which is why I've noticed the infotainment display goes off after 10 minutes to avoid running down the battery. (I've needed to power up the car again to get my music back.)

I didn’t test it, but at the same time, it seems strange to me that it was charging, because the battery had been connected to a trickle charger until recently, as I had spent the day updating the modules via SIPS.