Question about the 80%/20% rule for battery maintenance in winter


New Member
Stuff that hurts Lithium ion batteries:
-Sitting at high state of charge.
-Full depletions.
-Full charges.
-High charge rates / fast-charging.
-High discharge rates / full throttle, PAS 3-5.
-Charges when warm. (Ex: after a ride)
-Temperature cycling. (Indoor / Outdoor / Indoor / Outdoor)

Lethal stuff:
-Charging below -5C (So don't charge outside during the winter.)

So to maximize battery life, just be lazy with charging and charge up to a bit over 30% higher than what you'll need. If you need 25km, make sure you have 45km of range. That way you stay safely over 20%. That final bit of energy draw can be hard on the cells, but the detrimental part is when voltage/capacity drops off a cliff in the 4-8% range. Try to stay well away from that.

Oh, and do a full charge up once every month or two (depending on how much you ride) to balance the cells. Cells going out of balance doesn't really hurt anything, unless you get close to 0% regularly. An out of balance pack may have one cell hit 0% while others are still at 4%... 6%... 8%. That can be a problem, since the higher voltage from the stronger cells means the protection cutoff won't trigger before the unbalanced/weaker cell takes damage. Then your pack is pretty much destroyed. There's minimal harm doing more full charges and more balancing than necessary - but if you never let the Bike go under 30%, you could go a long time between full charges. It would maximize pack lifespan, but it requires far more thought and management effort.