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What are the symptoms of "phantom 16A charging"?

pdk42

Active Member
Jul 17, 2019
1,053
1,030
Leamington
It might look like a dumb question, but bear with me...

My car tonight started repeatedly ramping up charging to just over 16A and then pulling the power completely (down to 0) and then ramping up again to 16A then back down to 0, then up again, then down again - you get the picture. The only way I could get it to do a constant charge was to restrict it to 16A. Supply voltage looks good (235V). Is this the same as the phantom charging issue, or something else?

Thanks!
 

pdk42

Active Member
Jul 17, 2019
1,053
1,030
Leamington
Thanks. Yes, definitely something else.

I pulled all the breakers on the house distribution board except the charger and restarted - 32A solid. Then I added each circuit one by one and when they were all back it was still at 32A.

I've got builders in doing work on the patio and there is cabling under there that they're exposing so my guess is that it's something to do with that.
 

NewbieT

Active Member
Aug 16, 2019
1,028
626
North West
I had it once before, ramp-up, stop. > repeat. I stopped and started the charge it went away. Never happened since or before. It wasn’t on the current software version either.
 

pdk42

Active Member
Jul 17, 2019
1,053
1,030
Leamington
Just tried it again now and it starts charging fine. I've done nothing other than leave it a couple of hours. I'm at a loss to know what's going on. Was away these last four days and used a Tesla destination charger for three nights at a hotel without issue, so I'm beginning to think it's the charger or the supply at my house. It's all very frustrating!
 

pdk42

Active Member
Jul 17, 2019
1,053
1,030
Leamington
This was the behaviour I had a few weeks ago Charging Issue.mp4 . It happened twice, haven't seen it since. I wondered after whether it was related to a conflict with the ev.energy app?
Yep - that's exactly what I'm getting. A few points:

- I'm using what amounts to a dumb charger (it's a smart charger, but configured dumb), so it's not related to any smart-charger behaviour (such as with ev.energy).

- I find when it is doing this, if I restrict the max current to 16A (using the car's charging screen), then it works fine, but as soon as I go to 17A, it barfs (drops to zero and the process repeats).

- The problem comes and goes. When it's playing up nothing I've tried seems to fix it (and I've tried reseting the charger, rebooting the car, reconnecting cables, and pulling the breakers on all the other circuits in house), but then an hour or two later it'll just start working again.

My suspicions is that it's supply-related - or at least some interaction between the supply and the car. I used a Tesla destination charger at a hotel this past weekend and had pretty solid 32A charging for 3 consecutive nights.

I say "pretty solid", because even with the Tesla destination charger, I see occasional drops down to less than 32A. This is from the destination charger:

upload_2020-9-1_23-31-28.png


This is my charger last night once I got past the initial "won't go past 16A" problem:

upload_2020-9-1_23-34-18.png


It seems a lot worse at home!
 
Last edited:

Fly.guy

Member
Feb 11, 2019
88
82
UK
It looks as if your mains voltage is quite low and that it kicks up noticeably when the rate of charging derates. This would suggest that you have quite a ‘weak’ mains supply. Possibly at the end of a long circuit in a rural location ?

It could be that the car is noticing the low voltage and reducing charge rate as a protection measure. This might also explain why it behaved as expected when you dropped other loads by switching off all the other breakers in the house.

Is this yo-yoing also something you see when you set the car to charge in the small hours of the morning ? Overall load on your mains supply will be lower then and hence voltage would probably be a bit higher....
 
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pdk42

Active Member
Jul 17, 2019
1,053
1,030
Leamington
Thanks for your suggestions. Voltage might be an issue, but it never drops below 220V and my understanding is that the spec is 230V -6%/+10%. That means so long as it's 216V or more it's in spec. The TeslaFi logging doesn't show any dip before the cut-out, but that could be because the logging interval is too short. As a further pointer to it not being voltage-related, when it gets into its ramp-up/reset mode, it does this at 17A, when the voltage is around 225-230V.

However, it's true that I'm on the end of a small-village overhead power supply and I know that the DNO are planning some transformer upgrades in the village, so it could well be supply issues. But OTOH, in the middle of the night when there's little else going on either here or elsewhere in the village (there's only one other EV so far as I know), I find it hard to believe it's entirely down to that. At 3am I'm pulling probably no more than 35A total, which must be well within the limits.

It would be good if there were some detailed logs I could look at in the car to know what it thinks is going on. I know that Tesla service have access to more detailed logs, so maybe I should raise a service request and see what happens.
 
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