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Reduced charging rate

pdk42

Active Member
Jul 17, 2019
1,211
1,264
Leamington
My car has started reducing the charge rate on AC charging. It starts fine at 32A but after a little time (usually 5-10 mins), it drops back to 12A and stays there. I can see from the app that the charger is still advertising 32A (i.e. it displays 12/32). If I look at the car’s screen after the drop has happened, I can see this:

121A3C32-7130-4CA0-BFCA-A2CB5E2A10D8.jpeg


It’s obvious that the car thinks there’s a voltage drop, but I’ve swapped cables with no change in behaviour and have also charged another EV (ID3) on the same charge point and it works without issue. The supply here does show a decent voltage drop when pulling a lot of power (typically 240V down to 222V) but I’ve been charging for almost 18 months without significant problems (although I often see short periods of reduced rate overnight, but it’s usually down to 24A and for a short period only).

Ideas?
 
Interesting - I had that for the first time the other day. I had assumed there had been a real voltage drop but perhaps not. I also have typically 220V when there is other demand and the car is charging. That is not unusual so either the voltage dropped below that for real or perhaps the sensitivity has changed in recent firmware. Stopping and restarting the charge from my phone brought it back to 32A and it stayed there after that.
 
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pdk42

Active Member
Jul 17, 2019
1,211
1,264
Leamington
I took the car to a newly-installed BP Pulse 7kW charger this afternoon and it charged without issue. Voltage was a healthy 245V for the entire charge and the display showed 8kW. So I think I’ve got some supply glitch. We’re at the end of a long overhead supply at the edge of the village and I think some of the infrastructure is pretty dated too (especially the pole mounted transformers). Maybe there’s some additional load elsewhere that’s causing it. I’ll contact the DNO and see if they can take a look.
 
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@pdk42 if you use TelsaFi. TelsaMate or no doubt some other tools, you can see the details for each charge (voltage, current and resutling kW charge). It might be interesting to have that record when you speak to the DNO, everybody loves a graph! :)
It fluctuates a bit for during my charges as well, but I have never seen the message you had.
 

pdk42

Active Member
Jul 17, 2019
1,211
1,264
Leamington
@pdk42 if you use TelsaFi. TelsaMate or no doubt some other tools, you can see the details for each charge (voltage, current and resutling kW charge). It might be interesting to have that record when you speak to the DNO, everybody loves a graph! :)
It fluctuates a bit for during my charges as well, but I have never seen the message you had.
Yes, I have Teslafi, but the resolution of logging is too coarse to see what’s going on in detail.
 

Irata

Member
Oct 16, 2020
998
606
UK
Do you have anything in the house that shows voltage? For example, I have a UPS on the computer and it shows me the input voltage and can log to the minute.

Then you can see if the voltage drop is the whole house or just at the car.

Last year I sent a copy of my UPS logs to my DNO, they were fantastic and have since done reinforcement works to fix it.
 

Adopado

Well-Known Member
Aug 19, 2019
5,822
4,423
Scotland
My car has started reducing the charge rate on AC charging. It starts fine at 32A but after a little time (usually 5-10 mins), it drops back to 12A and stays there. I can see from the app that the charger is still advertising 32A (i.e. it displays 12/32). If I look at the car’s screen after the drop has happened, I can see this:

View attachment 650474

It’s obvious that the car thinks there’s a voltage drop, but I’ve swapped cables with no change in behaviour and have also charged another EV (ID3) on the same charge point and it works without issue. The supply here does show a decent voltage drop when pulling a lot of power (typically 240V down to 222V) but I’ve been charging for almost 18 months without significant problems (although I often see short periods of reduced rate overnight, but it’s usually down to 24A and for a short period only).

Ideas?

I can confirm that a screen reported 220v (or even below into the high teens) wouldn't normally cause the car to drop below 32amps. I could speculate that a brief bigger voltage drop occurred that the screen/app did not have time to log and then it came back up? If that was the case then it would be reasonable to expect that the charge would go back to 32amps after a restart.
 

pdk42

Active Member
Jul 17, 2019
1,211
1,264
Leamington
I can confirm that a screen reported 220v (or even below into the high teens) wouldn't normally cause the car to drop below 32amps. I could speculate that a brief bigger voltage drop occurred that the screen/app did not have time to log and then it came back up? If that was the case then it would be reasonable to expect that the charge would go back to 32amps after a restart.
Yes, it does go back to 32A after a restart, so your analysis is probably correct. I will try to see if I can get some better voltage monitoring.
 
Reduced supercharging on my Model S P85D - about half of what it was - but a surprise was a message that due to the supercharger station being in high use that I would also be restricted to 80% charge. (There were at least 2 stalls open.) Since my range also recently decreased abruptly, this lower range makes my car suspect to travel out of town on trips. Has anybody else seen this message on their screen while plugged into a supercharger?
 

Adopado

Well-Known Member
Aug 19, 2019
5,822
4,423
Scotland
Reduced supercharging on my Model S P85D - about half of what it was - but a surprise was a message that due to the supercharger station being in high use that I would also be restricted to 80% charge. (There were at least 2 stalls open.) Since my range also recently decreased abruptly, this lower range makes my car suspect to travel out of town on trips. Has anybody else seen this message on their screen while plugged into a supercharger?
It’s a common “restriction” …. Well it isn’t a restriction really as you can still set your charging level to a higher percentage if you need to.
 

Jason71

Active Member
May 8, 2019
4,027
4,296
Shropshire
Why would I get this message, then? I wasn't able to increase the percentage.
when the station is busy they automatically set the limit down to 80 to encourage you to leave at 80 and not hog the chargers. Normally you can still raise it manually to whatever you like. If they have changed that and you could not raise above 80% even manually then that is new/different.
 
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I could do with some advice on charge rate.
Plugged into a Rolec 2 x 22kw 3 phase supply at work, using the correct lead.

Starts charging at 16 / 16amp 44 mph 240v
then after 5 mins or so the amps fluctuate down as low as 6 amp with a charge speed of 12mph.
this can happen at any time during the charge.

Swap to the lower capacity lead ie limit to single phase and the charge sits consistently at 27mph 32amp.
Supercharging, home charging all perfectly ok.
Whats wrong???
 

Adopado

Well-Known Member
Aug 19, 2019
5,822
4,423
Scotland
I could do with some advice on charge rate.
Plugged into a Rolec 2 x 22kw 3 phase supply at work, using the correct lead.

Starts charging at 16 / 16amp 44 mph 240v
then after 5 mins or so the amps fluctuate down as low as 6 amp with a charge speed of 12mph.
this can happen at any time during the charge.

Swap to the lower capacity lead ie limit to single phase and the charge sits consistently at 27mph 32amp.
Supercharging, home charging all perfectly ok.
Whats wrong???
I would first try another 3 phase cable just to rule out a fault there. It could be heating up due to a poor internal connection. (Unless you already know that the cable works ok on other 3 phase charge points.)
 
M

Mr_Dave

Guest
Is it always the same charge point? Remember it’s the car that controls the charge rate and if the onboard computer detects a fault with either a spike or dip in current, the car will always adjust to protect itself. Try a completely different 22kW charge point using the 3-phase cable and try to eliminate each variable one at a time.
Also, even though it’s a 22kW charge point, and even with a 3-phase cable, the most the car will accept is 11kW AC.
 

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