Model Y onboard charger Voltage Tolerance?

[tomstephens89]

Hi all,

A friend of mine has a CTEK Chargestorm Connected 2 installed at home, 32A single phase. Frequently when charging his Model Y LR, the charger will receive a 'SuspendedEV' message, meaning the car is stopping the charge.

Being an electrical mind (We work together in a company of technical engineers), we investigated and found there to be a massive fluctuation of his supply voltage. Now his street is a 1930's build so the DNO's cabling is probably questionable but heres what we have found....

We are logging at 10s intervals the voltage reported by the Carlo Gavazzi MID approved meter in the charger and within the last 15 hours we have seen fluctuations of nearly 30v. And thats without him plugging the car in. Max was 263v and the Min was 230v. However, when he has been charging the car and encountered problems, the car has shown as low as 208v! We will continue to log and see if we can record that but I think theres a problem here....

My suspicion is that either some upstream cabling is badly undersized for the modern demands, or the transformer serving the street is on its way out or undersized. The fact that we have seen voltage as high as nearly 264v so far suggests to me that they may have already tried to compensate for the drop by increasing the transformers output voltage.

Question is, is this a problem for the onboard charger? I have a feeling the low points may well be (~208v) but what about the high (~264v)?

I know these are both way outside of the limits and the DNO needs to sort it out but the more evidence we have the better.

The DNO has been out to him and managed to identify the house is on a 'looped' supply with the neighbour. However they are on 100A fuses and no-one spotted any cabling sizing issues on the incomer. This suggests to me the issues are as I said... upstream cabling or transformer.

Does anyone know the voltage range of the MY onboard charger for the UK market?

Thanks!

 

[Andrew_SE23]

I presumed that the low voltage threshold is determine by the charger firmware or the sow are running on the MCU, i.e. it is just a variable set to reduce any damage to upstream components and not a technical limitation of the physical charger.

Is the message you mention from the CTEK Chargestorm? I don’t recognise it as a Tesla message.

 

[Morhydro]

In the UK, the declared voltage and tolerance for an electricity supply is 230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts. if you are getting consistent voltage outside these limits you need to contact the network operator in your area.

 

[tomstephens89]

In the UK, the declared voltage and tolerance for an electricity supply is 230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts. if you are getting consistent voltage outside these limits you need to contact the network operator in your area.

I know and he has.

I presumed that the low voltage threshold is determine by the charger firmware or the sow are running on the MCU, i.e. it is just a variable set to reduce any damage to upstream components and not a technical limitation of the physical charger.

Is the message you mention from the CTEK Chargestorm? I don’t recognise it as a Tesla message.

'SuspendedEV' is from the car. Its part of the charge protocol.

Further to this. We have continued logging and in the space of the last 12 hours, the supply has been at 270V midday. And this evening with the car on charge, down to 220v. Boiled the kettle at the same time and its down to 208v.

What a terrible supply.

 

[tomstephens89]

In almost 30 hours of logging, out of the 9900 samples taken, check this out:

Max V	269.4​
Min V	206.5​

File attached for those that are interested:

Voltage Log.csv

Shared with Dropbox

www.dropbox.com

 

[pdk42]

I've been suffering from a lot of voltage variation where I live. I see voltages as low as 208V and as high as 245V. The car usually throttles the charge rate back to 24A most of the time because it's unhappy with the voltage swings. I've moaned to the DNO, but all I get is tumbleweed.

 

[Sean.]

In almost 30 hours of logging, out of the 9900 samples taken, check this out:

Max V	269.4​
Min V	206.5​

File attached for those that are interested:

Voltage Log.csv

Shared with Dropbox

www.dropbox.com

I’d formally write to the DNO and complain. If no joy then take the complaint to the Energy Ombudsman or OFGEM

 

[tomstephens89]

I've been suffering from a lot of voltage variation where I live. I see voltages as low as 208V and as high as 245V. The car usually throttles the charge rate back to 24A most of the time because it's unhappy with the voltage swings. I've moaned to the DNO, but all I get is tumbleweed.

Capture that evidence and demand they resolve it. That is way below the UK prescribed limit for our supply.

 

[pdk42]

Capture that evidence and demand they resolve it. That is way below the UK prescribed limit for our supply.

Yeah, I think I'm going to have to step up the pressure. Can anyone recommend a decent voltage logger? The Teslafi logs are really too low resolution to help.

 

[tomstephens89]

Yeah, I think I'm going to have to step up the pressure. Can anyone recommend a decent voltage logger? The Teslafi logs are really too low resolution to help.

I'd use a fluke v3000fc or something that can be calibrated. Or a quality MID approved electrical meter that gives you a voltage output.

 

[Astrape]

Yeah, I think I'm going to have to step up the pressure. Can anyone recommend a decent voltage logger? The Teslafi logs are really too low resolution to help.

If you go to the charge log detail in Teslafi open the menu hamburger and click download as a csv file you get the data at minute intervals. For this purpose thats plenty of resolution. You only capture it while charging but thats probably a useful high load sample for your property anyways.

You could ask EO if they have the voltage data in the server record and ask if they could grab a weeks data and mail it to you.

The home automation guys will have a low cost way of doing this I expect using a plug in device.

 

[Fursty Ferret]

You could ask EO if they have the voltage data in the server record and ask if they could grab a weeks data and mail it to you.

Good luck, they were spectacularly unhelpful when I made a similar request last year.

Is it a tethered or untethered charger? I had a cheap(ish) 10m cable and it introduced quite a large voltage drop on a supply that was already dubious. Eventually it reached a point where three people close together had EVs, and the voltage drop as we all charged together required the DNO to lay a new cable down the street.

 

[Astrape]

Question is, is this a problem for the onboard charger? I have a feeling the low points may well be (~208v) but what about the high (~264v)?

When I investigated my charger dropping back to 24A (from 32A) I found that many people stated the drop back occurs if the supply voltage falls 10% from its starting level. One source stated 8%. My Teslafi drop was about 8% but obviously low sample rate so it may have gone lower.

My guess is that some greater drop results in the charge stopping completely. From a voltage trace if it happens regularly it may be easy to identify the level change that triggers this.

The charger circuit is not changed between US and UK so we say it works on the 208V US wall sockets (and 110). The low level of itself is not a problem.

High voltage also unlikely to be a problem see Info from Tesla - 277v feed to Wall Connector (HPWC) - Which Cars Support It

Does anyone know the voltage range of the MY onboard charger for the UK market?

This suggests up to 300V will not cause a trip in the car.

 

[tomstephens89]

When I investigated my charger dropping back to 24A (from 32A) I found that many people stated the drop back occurs if the supply voltage falls 10% from its starting level. One source stated 8%. My Teslafi drop was about 8% but obviously low sample rate so it may have gone lower.

My guess is that some greater drop results in the charge stopping completely. From a voltage trace if it happens regularly it may be easy to identify the level change that triggers this.

The charger circuit is not changed between US and UK so we say it works on the 208V US wall sockets (and 110). The low level of itself is not a problem.

High voltage also unlikely to be a problem see Info from Tesla - 277v feed to Wall Connector (HPWC) - Which Cars Support It


This suggests up to 300V will not cause a trip in the car.

That does make sense. It's the massive fluctuation which causes a problem rather than being high or low.

 

[MovingSouth]

We have continued logging and in the space of the last 12 hours, the supply has been at 270V midday. And this evening with the car on charge, down to 220v. Boiled the kettle at the same time and its down to 208v.

One possible cause of the symptoms you describe is that one or more properties on the DNO supply have had significant quantities of solar installed. That raises the line voltage at midday and doesn't overnight, of course. I believe that is one of the reasons why you have to seek permission from the DNO and why there is an output limit on how much you can export. Do do much and you fry your neighbours kit.

 

[Astrape]

That does make sense. It's the massive fluctuation which causes a problem rather than being high or low.

This means that one thing that may help is to turn a couple of kettles, fan heaters, or an electric shower and then start the charge. Then turn the other things off immediately and try not use them while charging. This will mean there will be a lower start voltage that the car uses as the starting comparison to decide if a subsequent voltage reduction is too great. With a lower start voltage there will be a higher chance of a successful charge.
Of course getting the DNO to sort their supply is the solution in the long term.

 

[tomstephens89]

Out of interest, I have exactly the same charger installed at my place ready for when my MYP comes and I've started logging the voltage of my supply as well via the internal meter.

Mine is rock solid. I even turned on the immersion heater, shower and boiled the kettle and it only pulled down from 245 to 235 with what's got to be a 10kW load nearly. See the start of the graph when I loaded up.

 

[Sean.]

The DNO has been out to him and managed to identify the house is on a 'looped' supply with the neighbour. However they are on 100A fuses and no-one spotted any cabling sizing issues on the incomer. This suggests to me the issues are as I said... upstream cabling or transformer.

Which DNO is it?

Has your mate asked them to unloop the supply?

 

[Astrape]

Out of interest, I have exactly the same charger installed at my place ready for when my MYP comes and I've started logging the voltage of my supply as well via the internal meter.

Mine is rock solid. I even turned on the immersion heater, shower and boiled the kettle and it only pulled down from 245 to 235 with what's got to be a 10kW load nearly. See the start of the graph when I loaded up.

Ye that seems like a small reduction but say the car sees the 245 as the start voltage. If it falls to 220 the charge will fall back to a lower rate.
You got to 235 with 10kW, so lets add another 7kW for your charger, now 228. Lets say there is 5% voltage drop in the wiring of your charger feed and car cable (not unusual) thats now 217V and the car will reduce your charger current. We havent started to consider the voltage falling further because of neighbours loads on the local supply cable.
As you can see things build up quickly, so be careful of calling it rock solid.

 

[Sean.]

Mine is rock solid. I even turned on the immersion heater, shower and boiled the kettle and it only pulled down from 245 to 235 with what's got to be a 10kW load nearly.

As @Astrape says don’t yet count your chickens….

You need to be measuring V at the charge point whilst the car charger is actually pulling a load to get a true gauge of the voltage drop / quality of (a) the supply (b) your cabling etc from the CU to your charge point.