Page Comparison

• Monitoring over-voltage, under-voltage, imbalance. How to separate conditions that are unideal for cells vs conditions that are genuinely dangerous?

  • over-voltage & under-voltage can lead to thermal runaway, better to leave car in this situation (genuinely dangerous situation)

• Currently, BMS will fault if cell goes lower than 2.5V. How much wiggle room is there/can we go a little lower than that or is that a hard limit?

  • We’re currently using LGM50 cells, but there is a newer version LGM50T that exists. The datasheet for LGM50T says 2.5V is the minimum guaranteed/recommended good operating voltage, but lower end for safety is 2.0V. Good cell performance cant be guaranteed (might lose capacity) if you go below 2.5V though. Upper end is 4.25V.

• How large of an imbalance should we allow?

  • Mayy be 0.1V-0.2V (need to confirm)

  • But overall, imbalance itself isn’t an issue. Imbalance is an issue insofar as over-voltage and under-voltage is an issue.

• What's the max current we can draw?

  • 52A

  • Max expected from motors is 30A, so we'll do check at 40A

• Safe temperature?

  • 50C for charging, 60C for operating/discharging

  • Shut regen off and solar input after 50C, firmware will need to update for this

• When should fans kick in?

  • Hard to say, but we’ll ideally want to keep below 50C because of the charging upper limit being 50C

Relevant data sheets in question:
LGM50: https://www.dnkpower.com/wp-content/uploads/2019/02/LG-INR21700-M50-Datasheet.pdf
LGM50T: https://www.batteryspace.com/prod-specs/11514.pdf