Hi all,
I was always curious about the 52kWh MEB cars like the ID.4 and how their AC charging would be limited to 7kW.
The 58 and 77kWh cars all support 7kW single-phase AC and 11kW three-phase AC. The 7kW limit for single-phase is standard and expected, because 32A is a normal limit for a single-phase charger. But, a 7kW limit that applies to three-phase AC charging is a bit weird.
Some non-MEB cars have 22kW AC chargers, which draw 32A on each of the three phases, and there are plenty of 22kW AC public chargers around. 11kW is more commonplace for the onboard charger in cars, translating to 16A per phase. A public charger with two ports could have a single 3-phase, 32A supply for a max of 22kW, and split the power evenly across two cars charging at 11kW.
When the MEB cars are limited to 7kW AC rather than 11kW, does that mean they don't do 3-phase charging at all? The problem would then be that in countries with 3-phase domestic supplies, the normal charger might be 11kW at 16A per phase. Being single-phase only would mean then that the car couldn't charge faster than 16A or 3.6kW.
Is it just a software lock? I have looked up the technical workshop manuals for the ID.3/ID.4 and they only reference a single onboard charger part number. Having a custom part just for the small number of smaller battery models would also seem a bit weird. A software limit to make it draw only 10A per phase would be technically simple, given that the car controls how much current it draws anyway.
I have an ID.3 with 11kW charging but my dad has an ID.4, and it's the one with the 52kWh battery and the 7kW limit. So I had a look, and the answer is not something I expected. The car can only charge on 2 phases! It's literally missing the pin for the third phase. So, when connected to a three-phase charger, it'll only draw 16A from the first two phases and then there'll be 16A running back through the neutral.
I think this is a similar pattern to how 7kW appliances are connected to three-phase domestic supplies in continental Europe. My Neff 7kW induction hob supports being connected to 1 or 2 phases.
It's not at all important but it's a mystery solved for me, at least.
