Why does EV charging slow down?

There could be several reasons for slowing down of charging speed.

The most common reason is, that when the State of Charge of your EV crosses 80% it automatically slows down the charging speed as a part of the battery protection mechanism, it’s function of vehicle’s BMS (Battery Management System). It damages the battery health if continues to charge at the same high speed above 80%.

If SoC is below 80% and if you see your EV is not charging at same speed as it usually charges, then below are certain other reasons for slowing down of EV charging,

1. Too Cold or Too Hot battery temperature and charging without preconditioning (Surrounding extreme weather temperature also affects charging speed)
2. Low State of Charge i.e. below 10%
3. Charge port latch is not properly engaged
4. Reduced charging amperage knowingly or unknowingly (either from EVs side or charger’s side)
5. Charging at lowered power output
6. Degraded battery health

Important Note: Please see, different levels of charging provide different charging speeds. Level 1 charging is slowest, Level 2 is faster and Level 3 is fastest. So don’t compare charging speed in-between with different levels of chargers.

Plus, even comparing between the same level of charger the power output will anyway affect the charging speed, i.e. lower power output will charge at lower speed than charging at a higher power output. That’s obvious, I hope you know that already.