I charged the Kona today at the Leviton EV charger at my local Hyundai dealer. The Charger is labeled 40A. The car got 6.7 kwh of charge.. Not sure if this is normal for commercial 200 Volt.. 200 Volt x 40 amps = 8 kw.. So, why am I only getting 6.7 kwh charge??
Why is that different at my house? My home EVSE is 32 amps and I'm getting 7.5 kw on the input side (dash readout). Why the .8 x 40A calculation? If I would do the same calculation on my home evse it would be .8 x 32A = 25.6 amps x 240 volts = 6144 watts but I'm getting 7500 watts, so it appears that the calculation multiplying the amperage by .8 only applies to commercial EVSEs??
Commercial buildings will have a 3-phase feed (3 hot wires, one neutral). https://en.wikipedia.org/wiki/Three-phase_electric_power If you measure from any hot to the neutral you get 120V, but if you measure across any of the two hot wires, you get 208V, not 240V. The reason is really that the two hots are 120 degrees out of phase and not 180 degrees out of phase. Single-family homes would rarely if ever have 3-phase service. Instead we essentially only get one of the 3 phases, and we typically only have two hots and one neutral. The two hots are 180 degrees out of phase, so if you measure across the 2 hots, you get 240V.
I understand that commercial wiring is 3 phase.. What I don't understand is electriceddy's multiplication of 40 X .8?? For example, there is a Chargepoint 32 amp station Downtown Lakeland. It is "rated 6.6 kw" and the actual power on the dash readout is 6.0 to 6.1 kw. 32 a x 208 volt = 6656 watts which is what the unit is rated.. the loss from 6.6 kw to actual power received by car could be considered normal loss.. Now, if I do the same calculation with the 40 a unit, it would be 40 a x 208 volt = 8320 watt, so I should easily get the maximum input wattage of 7.5 on my dash but I don't.. I'm just trying to understand the 40 * .8 calculation??? Why does that calculation not apply to the 32 amp commercial Chargepoing EVSE?
I have the same 32A EVSE at home and at work. At work the voltage is about 196V and I get 6.2A charging. At home it's about 240-245 and I get 7.5 or so. You can't assume the EVSE is getting 208V on 3 Phase wiring, just like you can't assume it's getting 240V on household wiring.
That's the slight disadvantage of level2 chargers at commercial properties ... they usually get 3-phase, so leg-to-leg voltage is lower. What's too bad is that the OBC can't or won't figure this out and simply draw more current to make up for it, especially if your nice 40A EVSE is telling it that it's fine to do so! But the OBC seems to simply limit by current, 30 or 31 amps or whatever, which is pretty dumb. Now, if we had more type-2 connector adoption in the US *with* 3-phase charge capability, we'd be happily pulling 10 or 11 kW at public level-2 stations all the time... _H*
I hear you Hobbit. Here in France I am quite frustrated by that (DC charging is fine and up to decent, circa 50kW speeds). But on the public, 3-phase Type-2 plugs (as you have mentioned) I can only draw single-phase and therefore 7.1-7.2kW... These crappy Renault Zoe cars here draw 21kW (or 3X my single-phase ergo they must have the adequate inverter) on the same Type-2. PS: I say crappy because of smaller batteries and the fact that they drive like a slightly quick golf-cart (my neighbour has one) and he prefers my Kona.
in NZ our commercial properties get 400V 3-ph which is conveniently 230V P-N. The vast majority of homes normally just get one phase, 230 V @ 63 amps, but I learned yesterday that some are supplied with 2 phases to get past that current limitation but avoid the install and metering cost tier of 3-ph. Weird ...
