Can't charge lithium batteries when cold?

rgk1rgk1 Solar Expert Posts: 132 ✭✭✭
All the lithium batteries I see say they cant be charged when temps are freezing.  How can you charge an electric car in cold climates?
4-Risen 320 watt in series/parallel, 8-215ah 6 volt GC2 batteries in series, Exeltech 1100 watt/48 volt inverter, Tristar 45 MPPT controller.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,027 admin
    Here is a Tesla in Norway... Driver has a OBD monitor of some sort so he can see more details "inside" the car's electrical systems and sensors:

    https://insideevs.com/news/381384/cold-weather-effects-on-model-3/

    Basically, charging power is severely with near 0C cold soaked battery bank--And something like 1/2 the reduced "charging" power goes into heating the battery system (some models of Tesla specifically have battery heaters?).

    Some other background:

    https://teslamotorsclub.com/tmc/threads/9kw-stator-heater-on-when-supercharging-hypocritical-waste.181005/

    It looks like (guessing) that the motor stators are heated (traction motor is "energized" but not turning--That energy is being turned into heat, which is then moved to the battery pack--I think) and the "coolant" loop goes to the battery bank to help heat them (no specific battery heater in this model?).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RCinFLARCinFLA Solar Expert Posts: 1,399 ✭✭✭✭
    They use heaters.  When battery pack is insulated it does not take much power to keep batteries warm.  Once car is in use the self heating of cells provides all the heating.
  • rgk1rgk1 Solar Expert Posts: 132 ✭✭✭
    Guess that makes sense.  Was hoping to move to Lithium from FLA but mine live in outside, unconditioned space.
    4-Risen 320 watt in series/parallel, 8-215ah 6 volt GC2 batteries in series, Exeltech 1100 watt/48 volt inverter, Tristar 45 MPPT controller.
  • RCinFLARCinFLA Solar Expert Posts: 1,399 ✭✭✭✭
    edited August 16 #5
    Charging LFP at cold temps causes lithium plating on graphite anode side.  Beside consuming available lithium reducing capacity of cell it can also create metal dendrites that can punch through separator creating shorting paths within cell. If the shorts get bad enough the self heating can cause a cascade thermal runaway of the cell.  

    Ion migration slows down the colder the temp on cells.  This increases cell impedance and terminal voltage drop reducing ability to deliver higher currents.  Best if you can keep cells above +10 degs C.


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