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Harold Halewijn avatar image
Harold Halewijn asked

EV Charger calibration issues

Hi, I'm using the EV Charger (old style) for 12 months now. Until now I didn't pay attention to the power calibration so I can't tell you if this was differently with previous firmware versions.

If I want to charge 3-phase cars, I have to set the power calibration setting to 0.8 to reflect real power. I can check this with smartmeters in my cabinet. But when I charge a hybrid-car (single phase) I have to change the calibration setting to 1 to see real power taken.

schermafbeelding-2023-08-18-105643.png

These pictures show the charging of single phase. You can notice the charge rate reported by EV Charger (2783) and the AC loads (4729, there are some small additional loads there).

schermafbeelding-2023-08-18-105730.png

Above picture is with power calibration set to 0.8

next picture shows right value after changing to 1.

schermafbeelding-2023-08-18-105747.png

If yoy want, I can supply the same pictures for a 3 phase car.

Why is this?

ev charging station
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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ commented ·
Hi, the power measurement is not very precise as we are only measuring the current and not the voltage. So the power displayed is just an approximation
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kudos50 avatar image kudos50 Lucian Popescu (Victron Energy Staff) ♦♦ commented ·
That's kind of a big oops for me as I'm using the numbers to do expenses every month.

Also, Harold is mentioning 0.8 and 1.0 to get his numbers matching from 3 to one 1 phase. That's a 20% difference whereas he most definitely never ever has a 20% voltage sag during charging.

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kudos50 avatar image kudos50 Lucian Popescu (Victron Energy Staff) ♦♦ commented ·
If you have a moment @Lucian Popescu (Victron Energy Staff) I think this thread is pretty important for some users including myself. I have also read the thread about users discussing the future/new reporting feature in VRM to charge their company or their employer. All of that is not realistic if the numbers are this far of.

For me there is no way to explain the 20% gap that Harold has experienced just because you don't know the voltage. If his numbers are showing up on other users dashboards as well, this is not "just a minor inconvenience". Specially because people don't even realise they actually have a problem to begin with.


If it's only the voltage that is missing and the current is pretty accurate, it would not be too difficult to "help" those users by writing a flow that sets the EVCS power calibration automatically based on the voltage you are using for your estimations (230 I presume) and the voltage taken from the grid meter or the inverter. This would not be 100% accurate and it will not cover power factor deviations during the start and stop process. But it will come closer than what you have now if charging at night with no wind energy (225V?) or by day if the whole neighbourhood is generating solar (235V and up)?

But all this does not fix nor does it explain the 20% gap.

I had a funny experience myself this afternoon. A friend had his M3SR set to 100% and at the end of the charge process the car was only taking 1kW for a long time. As the house was empty and almost everything is metered I know for a fact there were no other consumers with significance. The ac-load said 1.1kW spread over 3 phases, the car said it was taking 1kW, but the charger said 0W charging. Lasted for over 30mins if memory serves me well. This showed both on VRM and on the charger webpage.

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