Model 3 12 volt battery location

[strykeroz]

I am quite surprised they have not changed this lead weight over to a Li battery chemistry and remove 20 lbs.

What intrigues me is it's needed at all. If the propulsion battery remains connected to keep this charged, why not directly connect the 12V rail through a voltage regulator rather than having this secondary battery? It would avoid the weight entirely, remove a consumable and a point of failure, and the inefficiency of charging/discharging from the design.

There must be a reason, I just don't see it?

 

[SomeJoe7777]

What intrigues me is it's needed at all. If the propulsion battery remains connected to keep this charged, why not directly connect the 12V rail through a voltage regulator rather than having this secondary battery? It would avoid the weight entirely, remove a consumable and a point of failure, and the inefficiency of charging/discharging from the design.

There must be a reason, I just don't see it?

For safety, whenever the vehicle is parked and unoccupied, you want the main HV contactor to disconnect the HV battery from everything. You need this for safety (fire/flood/etc) and for maintenance so that you can work on the drive systems and charging systems without battery voltage present.

With the contactor disconnecting the HV source, then you need some type of low voltage battery to run the electronics systems.

 

[strykeroz]

That makes sense now. Thanks

 

[iwannam3]

What intrigues me is it's needed at all. If the propulsion battery remains connected to keep this charged, why not directly connect the 12V rail through a voltage regulator rather than having this secondary battery? It would avoid the weight entirely, remove a consumable and a point of failure, and the inefficiency of charging/discharging from the design.

There must be a reason, I just don't see it?

The reason it is lead acid it that lithium batteries don't work at very cold temperatures. That's why Tesla heats the main batteriy in low temperature environments. People have changed to lithium in warm climates.

 

[int32_t]

Wait a minute.

My wife won't let me leave the car plugged in at night. She's worried that a thunderstorm will come up, and ruin the car and the house!

She even makes me unplugg the TV whenever there's a thunderstorm nearby.

She's not the only one. When dark clouds form, I scurry about making sure everything that's nonessential is unplugged. Backups are unplugged first!

 

[seattlite2004]

That is **sooo*** much simpler than the Model S, both to reach and the stuff attached.

No more reason to go to a Tesla service center for a 12v battery change. <<sighs with relief>>

Assuming one can get a replacement 12V battery outside of the Tesla Sevice Center.

 

[FlatSix911]

That is **sooo*** much simpler than the Model S, both to reach and the stuff attached. No more reason to go to a Tesla service center for a 12v battery change. <<sighs with relief>>

The good news ... Tesla has now moved the 12V battery location to the frunk on the facelifted Model S.

 

[FlatSix911]

The reason it is lead acid it that lithium batteries don't work at very cold temperatures. That's why Tesla heats the main batteriy in low temperature environments. People have changed to lithium in warm climates.

Here is one of the new 12V Lithium batteries available for direct replacement of the old lead-acid unit.