32A vs 40A vs 48A vs 80A — what your car can actually use.
Short answer: The charger's amperage rating is the maximum it can deliver. The car's onboard charger sets the maximum it can accept. Installing a 48A charger for a car capped at 32A wastes money — the car will charge at 32A regardless. The right amperage is whatever matches your car's onboard cap. For most modern EVs that's 48A; Bolts and older Mach-Es cap at 32A; Ford Lightning with Charge Station Pro caps at 80A.
The chain of caps
Your EV charging rate is determined by the lowest of three numbers:
- Your home's electrical panel capacity (100A, 125A, 150A, 200A)
- The charger's rated continuous output (32A, 40A, 48A, 80A)
- The car's onboard charger maximum (32A or 48A for most cars; 80A for Ford Lightning w/ Pro)
The slowest link wins. Installing a 48A charger doesn't make a Bolt charge faster — the Bolt's onboard charger caps at 32A, so it charges at 32A regardless.
Car-by-car onboard caps (2024 model year)
- Tesla Model 3 / Y / S / X / Cybertruck — 48A
- Ford F-150 Lightning (standard) — 48A
- Ford F-150 Lightning + Charge Station Pro — 80A
- Ford Mustang Mach-E (2022+) — 48A (older Mach-E was 32A)
- Rivian R1T / R1S — 48A real-world (despite marketing of 80A onboard)
- Chevy Blazer EV / Equinox EV — 48A
- Chevy Bolt EV (all years) — 32A
- Hyundai Ioniq 5 / Kia EV6 / Genesis GV60 — 48A
- BMW i4 / iX / i5 / i7 — 48A
- Mercedes EQE / EQS / EQB — 48A
- Polestar 2 — 48A
What each amperage actually gives you
- 32A continuous = 7.7 kW → ~23–29 miles/hr depending on efficiency
- 40A continuous = 9.6 kW → ~28–35 miles/hr
- 48A continuous = 11.5 kW → ~32–37 miles/hr
- 80A continuous = 19.2 kW → ~55–60 miles/hr (Lightning-only)
The NEC 625 continuous-load rule
National Electrical Code section 625 requires the breaker to be sized at 125% of the continuous load. So:
- 32A charger → 40A breaker
- 40A charger → 50A breaker
- 48A charger → 60A breaker
- 80A charger → 100A breaker
This is why a "NEMA 14-50" outlet (rated 50A) only delivers 32A continuous — the 80% rule applies to portable charger amperage as well.
The right amperage rule: match the charger to the car's onboard cap. Anything higher is wasted money. The free panel check from a network installer determines what your car can use and what your panel can support.