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Discussion Starter · #1 ·
Hi there. I have recently had a Zappi Myenergi home charger installed (professionally). Pleased with the charger itself and installation was all fine.

However, when I charge the car it seems like a large percentage of the energy pull from the grid appears to go into the house (image attached).

Is this something that you would expect, that the charger pulls much more than it puts into the car?
Thanks in advance...
140815
 

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Do you have home / solar batteries that charge at the same time?
 

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That makes sense. The home used 9.0 kWh and the car 31.2 kWh.

Total imported from the grid was 40.3 kWh.

I assume you don't have solar or it wasn't generating much that day?
 

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I really wouldn’t expect that and get nothing like that with my Zappi, it just correctly reports the actual output to the car and house consumption correctly.
I would hope on a newly tested install you don’t have a wiring fault that is sinking 2kW of power somewhere before it reaches the output of the Zappi, something would be melting if so.
Seems far more likely to me that the current sensor that the zappi installer should have fitted around the incoming live mains connection is not quite right. It seems to use this to measure overall inbound power demand, and then subtracts what it measures going to the car in order to generate the ‘home’ value. If this is placed in a tight consumer unit access space it may have an additional wire contained within it or be on the wrong tail or something like that?
 

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As this is overnight and probably the home should be consuming very little unless you have batteries then would be useful to know what the home consumption is without the Zappi charging - then you can see if the CT is located correctly?
 

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Don't forget there's around 10% energy loss when charging an EV (maybe even 15%, depends on the particular EV). So if your car reckons you've added say 40 kWh to it, the Grid/whatever will have had to supply more like 44 kWh. That extra 4 kWh went into resistive losses in the battery itself, which warmed up as a result & may have cooled off since (which is why we like finishing a charge just as we're about to leave, if poss), other losses will be power to run the car's computer, and internal mains charger boosting 250V AC up to 400V DC etc.
 

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Discussion Starter · #8 ·
Thanks for all the replies. I’ll try MyEnergi support.
For reference: it’s a Tesla Model 3, yes it was overnight so no solar incoming and no other usage in the home so the 2kW extra is unexpected. As is suggested it perhaps looks like a CT clamp issue. As far I can tell the setup looks alright but I’m no expert!!
 
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