# Forums

## Battery Preconditioing and Energy Usage in Winter

Battery Preconditioning and energy usage.

Submitted by FISHEV on November 12, 2019

We has a very informative thread on the "Battery Preconditioning" that comes when you navigate to a Tesla SC and the battery is cold.

The facts that emerged.

1. There is no dedicated heater for BP in the model 3. It uses heat from the motors to heat the battery via the liquid temp control system.
2. The BP is done by inducing inefficiency in the electrical usage of the motors to create additional heat.
3. The heat is routed to the battery to warm it.
4. If the car is moving slow or stopped in traffic and the motors are generating heat to warm battery then you can see a significant power draw on the battery.
5. If the car is traveling at speed, the motors will be likely be generating enough heat to warm the battery with less impact on efficiency.

These facts (as best I remember them) were posted by @jallred. He can look over my conclusions from the deleted thread and correct.

Magic 8 Ball | 13 november 2019

Roll eyes

andy.connor.e | 13 november 2019

"He can look over my conclusions from the deleted thread and correct."

Its deleted xd

FISHEV | 13 november 2019

Took out the example as it was a distraction.

Did have a math question. Assuming the car is sitting in traffic, not moving but BP is on. Using the 7kW what one test showed for BP stationary, if one was sitting for 20 minutes in traffic is this who much battery capacity will be used in 20 minutes?

7kW rate to heat.
20 minutes sitting
4.13 miles per kWh of battery capacity.

7kW x .33 (20/60 minutes) = 2.33kWh
2.33kWh x 4.13 = 9.64 miles of range.

lbowroom | 13 november 2019

"you can see a significant power draw on the battery"

by all accounts, no

andy.connor.e | 13 november 2019

As it was previously stated to you, that your math is correct but that does not mean that the computer system is displaying you the same information.

jimglas | 13 november 2019

not again …..

Bighorn | 13 november 2019

7 kW only happens in Park.

andy.connor.e | 13 november 2019

@jim

Again. Today, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day, and the next day.

WhiteWi | 13 november 2019

100th time. Yahooo. Fish the unstoppable

MAB1980 | 13 november 2019

For those playing along at home, this is at least the third thread with a list that goes 1, 3, 2, 3, 4, 5.

Important in the last one, derotam listed some requisite information needed to understand what the very first of these threads asked, and that information had never been provided.

FISHEV | 13 november 2019

"....your math is correct but that does not mean that the computer system is displaying you the same information."andy.connor.e

Well none of the example was anything the Tesla displayed. The 7kW max power to heating battery was from @Bigorn. Just used it for a plug number. The 4.13 miles per kWh is Tesla math on my range of 310 on 75kWh battery.

FISHEV | 13 november 2019

"7 kW only happens in Park."@Bighorn

Stopped in traffic with H(old) might be the same thing to the Tesla.

Wonder how he got the car to do the that if Battery Preconditioning does not come on when car is not moving?

Bighorn | 13 november 2019

Data collection, on Reddit and by Bjorn, were both performed on stationary vehicles. My experiment was the only one to be done in motion, traveling to the SC. I was able to get Preconditioning to activate while Parked in my garage. Hold and Park are not likely equivalent in this situation since the car is in Drive on hold.

WhiteWi | 13 november 2019

@FISHEV, oh I remember you said nobody knows battery size of M3 but Tesla and they ain't telling us. But know you know the size. Fish:"75kWh battery". Hmmm You are truly Royal Etron )

derotam | 13 november 2019

Thank you FISHEV. As others stated your 2.3kWh is correct for your math problem.

From what I have seen with the CANbus data, whether in Park or Hold, the battery preconditioning does the same thing. I can re-verify here in a few minutes when I run an errand but I am pretty sure that's what I remember.

jimglas | 13 november 2019

why is this even a thing?
Just plug your car in and charge it

derotam | 13 november 2019

@jimglas, this all goes to the fear of battery preconditioning using so much power when you are already at a low SOC for whatever reason. If someone thinks there is a MASSIVE draw by preconditioning that is an issue and we are trying to temper that fear by figuring out / explaining the maximum draw possible.

jimglas | 13 november 2019

I suspect that if there is going to be a problem, the car is smart enough to turn it off
Just like it tells you to slow down if you are running on fumes

Magic 8 Ball | 13 november 2019

“Just like it tells you to slow down if you are running on fumes”

But there would be no FUD if that were the case.