I have very happily had a OpenEVSE charger for a few years now, it was professionally installed and has been working well.
I have it setup so that it sleeps when our electricity tarrif is expensive and charges when it’s cheap. This means that under normal operation it sleeps for a long time and then starts charging for a few hours over night.
When doing this it seems to reliably error with a “no ground” fault, however if I plug the car in and immediately start charging it works with no problems.
I haven’t changed anything about the setup or done any updates before this error started occurring, so I am at a bit of a loss.
I was hoping to get some advice on if this is likely to be a charger or firmware issue vs a wiring issue for which I should get an electrician round.
@Cadair do you mind sharing what the exact fault with the circuitry was? Our charger is seeing lots of “no ground” faults too, but the electrician just checked the Matt:E device and said there were no issues. As a result, he advised turning off the ground monitoring, but the charger still powers down for hours at a time. I’ve yet to find a pattern, in terms of time on/off our network.
[edit] amps and volts since monitoring last week looks like this
So, for info.. this turned out to be the PCB controller in the Matt:e. The original unit (an SP-EVCP-B) is 2-4 years old, and that came with a PCB covering the older standard voltage range.
Apparently the British standard has since changed and the voltage range covered went from 207-253V (230-+ 10%) to have an upper limit of 262V.
Matt:e tech support, who were great, said that some EV chargers have had issues when loads fluctate on local networks, due to the increased numbers of heat pumps and solar panels, hence the BS standard changing.
It was swapped earlier (see image), and the car charged around midday with our solar panels exporting at about 4kW, which would normally mean the charger went off until the loads dropped to below 253V. A £100 fix rather than much more for a new Matt:e or even charger (as the earthing functionality is built in to most chargers now, apparently)
That’s great to hear Matt:e has resolved the issue. However, AFAIK the grid voltage standard has not changed, it’s still 253V. I just checked this with a couple of DNOs, and they still state 253V max. I’m sure @Robert.Wall will be able to confirm?
It sounds like Matt:e are relaxing the threshold where they consider high voltage to be a potential PEN fault, this is the purpose of a Matt:e box.
262V is significantly above the maximum grid voltage and could potentially damage equipment, e.g your EV. I would recommend notifying your DNO, they will probably install some logging equipment to verify your voltage and potentially look at tapping down the transformer in your area to reduce the voltage.
I’m certainly not aware of a change to the rules, but as we all know, increasing amounts of private generation (PV mostly) is creating problems with grid instability. It’s quite likely that there will be local areas where the voltage can go higher if there’s a concentration of local generation. The BS change will be to take account of this, to give some assurance that your equipment won’t be damaged. As Glyn implies, it’s probably not something that can be controlled even regionally, and means someone coming to your local sub-station to change a transformer tap.
UK Power Networks give the range as 230V -6% +10%, so 216.2V to 253V UK Mains Voltage
I checked as I thought that I was told -5% +10% a couple of years ago when we were experiencing significant issues with the supply on the lane - there were several new solar PV installations and we were recording a mean in excess of 253V. SSE logged it for a couple of weeks and then about a year later it suddenly dropped to a mean around 240V - my neighbour’s EV charger is a lot happier!
"The standard domestic mains supply for Europe is 230 V ± 10%, giving a lower limit of 207 V and an upper limit of 253 V. It is permissible under BS 7671 to have a voltage drop within the installation of 5%, which would give a lower limit of 195.5 V. The UK standard prior to harmonisation was 240 V ± 6%, giving an upper limit of 254.4 V.
Although the UK nominal standard is now 230 V, the supply system has not generally been adjusted, and the voltage centers around 240 V."
(This was correct when it was written many years ago now, it was published here.)
which is also the present EU standard. It closely approximates to 240 V -10% +6%, so in effect our old UK standard has been extended downwards by 4%.
Long before I got an OpenEVSE charger and Matt:E, my inverter would trip out with grid over voltage when sunny, as did others in the village.
The DNO even went around moving us to different phases on the poles to try and balance out the problem.
I got fed up dealing with the DNO and installed an Optivolt100, running it on the 4% tap which resolved the problem for me.
It does however give me a low voltage issue in the winter when my house will go below 216V and trip the Matt:E. (Lots of EV chargers and heating pumps in the village as well as solar!)
That problem is solved by using the shaper facility on the charger to restrict car charge on those occasions.
Maximum voltage yesterday measured by the emonVS was 244.4V (this is after the Optivolt) so circa 254V and the therefore it’s doing the job still.
