Tesla "AC ripple current" during DC supercharging
Posted: Sat Jan 11, 2025 12:14 pm
Just been reading about a new feature that Tesla has apparently enabled to help heat batteries during Supercharging.
They're injecting voltage variations into the DC power in order to induce an AC ripple current across the battery, with the sole purpose of generating waste heat.
This is only for certain car types in certain conditions.
Single motor vehicles
Standard range battery (ie. LFP chemistry)
State of charge below 48%
Ambient temperature at or below 0C.
This is because LFP is particularly hamstrung by being cold soaked (coldgate as TeslaBjorn would say), and because Tesla's battery heat source comes from the motors themselves being made to run in an inefficient, and therefore heat-generating mode, with only 1 motor, there's not as much heating power available as they would like. I've read that dual motor cars deliver 7kW of heating in that mode, so assume single motor can only push out 3.5kW.
Have to say that's pretty clever.
https://www.speakev.com/threads/ac-ripp ... rs.189130/
They're injecting voltage variations into the DC power in order to induce an AC ripple current across the battery, with the sole purpose of generating waste heat.
This is only for certain car types in certain conditions.
Single motor vehicles
Standard range battery (ie. LFP chemistry)
State of charge below 48%
Ambient temperature at or below 0C.
This is because LFP is particularly hamstrung by being cold soaked (coldgate as TeslaBjorn would say), and because Tesla's battery heat source comes from the motors themselves being made to run in an inefficient, and therefore heat-generating mode, with only 1 motor, there's not as much heating power available as they would like. I've read that dual motor cars deliver 7kW of heating in that mode, so assume single motor can only push out 3.5kW.
Have to say that's pretty clever.
https://www.speakev.com/threads/ac-ripp ... rs.189130/
