Actually, there are several pieces here... Each configurable at some level.
- The car, and if it is setup to use a single charger / standard charger (40A) old style dual chargers (80A), or high amperage charger upgrade (72A), as well as the internal configuration of the car (which can be set to pull a lower amperage if needed).
- The wall charger, You can configure the HPWC for the maximum available amperage using an internal switch. This setting will tell the car how much power (amps) it could take, assuming the car can take that much based on the charger(s) and configuration setting. Note, this can actually be set lower than 40A if for some reason your system cant handle a full 40A circuit (60A breaker)
- The supply, including wires, circuit breaker, and supply. While the car and wall charger can talk to each other and will negotiate the best speed, the power supply side is not "smart" and you have to tell the wall charger how much power is available. the important thing here is to make sure that the HPWC is set to draw NO MORE THAN the limit that the power supply can handle. So, if you use a 60A breaker, you SHOULD NOT set the HPWC higher than that (actually a bit lower, but there is a conversion chart in the docs). or even if your breaker is 100A, but you are using wires that are not large enough, you would need to set the HPWC at the level that the wire can handle. If the HPWC was set higher than the supply could handle, it could either trip the breaker each time it started, or even start a fire in an extreme case.
so, some examples (assuming no electrical problems and the car charging settings at max)
- single-charger car -> HPWC(set to 40A): Will pull 40A
- dual-charger car -> HPWC(set to 40A) Will still pull only 40A
- single-charger car -> HPWC(set to 80A) will only pull 40A
- dual-charger car -> HPWC(set to 80A) will pull 72A/80A (depending on the car version)
So, you don't have to set the HPWC for 40A to limit it for the car... the car wont pull more than it can handle.