Electric Cars
Slow Public Fast Charger: Why Charging Speed Drops
The fast charger starts at full speed, then drops to 30-50 kW and stays slow.
What causes it
Battery thermal throttling, a charger derating under shared load, a low battery percentage, or a car-side limit on charge curve.
What to do
- Charge from a lower starting point - the curve is fastest from 10-50%; starting at 70% is always slow.
- Check if the site is shared - two cars on one 150 kW unit split the power; move to an empty stall.
- Precondition the battery - a cold battery charges slowly; navigate to the charger so the car warms it first.
- Try another station/network - some networks and stalls are consistently faster.
- Update the car's software - charge-curve optimizations are common over-the-air fixes.
Realistic expectations
- 10-50% is the fast zone (100-250 kW depending on car).
- 50-80% is medium (50-100 kW).
- 80-100% is slow for everyone (20-50 kW) - leave early.
Plan stops to charge 10-60% instead of waiting to 100% and you cut total trip time dramatically.