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Limit AC charging power

1462 Views 5 Replies 3 Participants Last post by  bstringer
Dear EQC owners and fans,
I have a home charger (22kW) that I use to charge the car at the maximum value of 11kW.
A new rule in coming that increase the price of electricity proportionally to the peak power.
As consequence I would like to reduce the maximum AC loading using the home charger.
Is there a functionality in the car that allows this limitation?
(I have tried but it seems that the limitation of power only applies when the car is connected to mains= via the "normal plug")?
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(I have tried but it seems that the limitation of power only applies when the car is connected to mains= via the "normal plug")?
Correct. I don't think there's anyway to do it from inside the car. But you should be able to wind it back inside your EVSE (aka wallbox, aka home charger). Is it something you want to just wind back once and leave, or do you want to be able to set it to different charge levels at different times? Most EVSEs require you take a cover off to get to that control. Here's how it's set on mine:

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Thank you dBC,
that's what I was doubting, I have tried the "max current" option of the car but indeed it does not work.
What I would like to do is to limit the absolute maximum peak, so to a given fixed value (e.g. 7kW), not flexible.
Unfortunately my wallbox is fully digital, it can be configured to do this, but only by an installer (need special admin right for the config APP).
I was trying to avoid paying 150€ for changing a simple setting in the wallbox (probably 2 minutes work), but it seems that I have no choice.
I think that still for such an expansive car, this flexibility shall be included.
I'm guessing it's a tethered wallbox? If it were a BYO-cable wallbox you could potentially achieve the same result by buying a 32A single-phase type 2 cable... then it would only charge at about 7.4kW. But a new cable might cost as much as getting the installer to reconfigure it.

I know there are a few countries bringing in peak demand based charges, so those installers are probably going to make some easy money. I'm pretty sure on a Tesla model 3 you can dial up whatever AC charge rate you want in the car. It's not clear why MB restricted that setting to just the "nonna plug".
Something else that might work, if you've got access to a friendly electrician happy to experiment, is to just disconnect L2 and L3 at the breaker. My wallbox is a 3-phase version with the knob above set to 'A', which basically makes it a 22kW capable wallbox like yours, but only one phase is wired up (I only have one phase) so the car happily draws 32A on that phase and charges at 7.4kW.

That assumes your energy provider bases their new peak demand calculation on your net peak power across all 3 phases. If they base it on maximum current on any one phase, then this suggestion would make things worse - you'd be drawing 1x32A instead of the 3x16A you're presently drawing.
I was surprised that the EQS does not seem to have a way to limit the charge rate. I had owned a Tesla Model S and their charge interface allowed the user to set the number of Amps that the car would draw. There are times when one may be charging at an outlet that will not deliver the amount of current that it should and a breaker will trip. Lowering the maximum draw of the vehicle can address this issue proactively.
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