Is my charger working correctly?
Discussion
Hey all, I've had an Ohme Home Pro charger installed recently. The electrician who fitted it at the weekend left the job half-finished, saying he didn't have a data cable to hooke something up. Another electrician from the same firm came out today and said no data cable was needed as the Ohme units use a 4G simcard. As I learned later, despite his assurances, I think he might have been wrong.
I've plugged my car in, it's currently charging at 2.4kwh. I thought this seemed a bit slow, isn't the Ohme supposed to be a 7kwh unit like other chargers?
I thought perhaps this was changing slowly due to my Ovo Charge Anytime tarrif, so the device was drawing current more slowly, as I'd scheduled the charge to end at 9am tomorrow, I thought it may be measuring out the juice. According to the Ohme app, can should be at 90% charged tomorrow morning, so there's no need to rush the charge.
Out of interest, I click the 'max charge' button to see if that would speed it up, as it should theoretically put it on the fastest charge available (for times when you just need the car charged, schedule be damned). This also seemed to max out at 2.4kwh, but it did think it could take my car from 30%-90% in 6 hours.
I note the CT clamp reading on the screen is 0.0, which according to Google, isn't right. A little look at the installation guide indicates this does need a data cable which is attached to the CT clamp on the charger and to a wire near the electricity meter.
I'm 90% sure at this point that I'm going to be calling the electrician back. Give me a common sense check here, my charger should be pulling 7.4kw, should it not?
I've plugged my car in, it's currently charging at 2.4kwh. I thought this seemed a bit slow, isn't the Ohme supposed to be a 7kwh unit like other chargers?
I thought perhaps this was changing slowly due to my Ovo Charge Anytime tarrif, so the device was drawing current more slowly, as I'd scheduled the charge to end at 9am tomorrow, I thought it may be measuring out the juice. According to the Ohme app, can should be at 90% charged tomorrow morning, so there's no need to rush the charge.
Out of interest, I click the 'max charge' button to see if that would speed it up, as it should theoretically put it on the fastest charge available (for times when you just need the car charged, schedule be damned). This also seemed to max out at 2.4kwh, but it did think it could take my car from 30%-90% in 6 hours.
I note the CT clamp reading on the screen is 0.0, which according to Google, isn't right. A little look at the installation guide indicates this does need a data cable which is attached to the CT clamp on the charger and to a wire near the electricity meter.
I'm 90% sure at this point that I'm going to be calling the electrician back. Give me a common sense check here, my charger should be pulling 7.4kw, should it not?
SteBrown91 said:
The ohme uses 4g to communicate to the Supplier/Ohme etc but it will need a data cable from the CT clamp to the charger.
Yes, I just found something about this in the installation guide on the Ohme website. Electricians called, now coming back for what will be the 4th visit to my house to fit this charger.Go electric, they said, it's so easy, they said
Well, at least I've got some chargers close to home if I need to go somewhere urgently. Charging at 3-pin speed would take forever.
Depends on your needs. I've used 3 pin at home for 13 months now. 5 hrs per night at 8.5p per kW. 
I have had to use a total of 49 hrs at the 'day' rate when I used it a lot (yes, I've kept a spreadsheet), 939 hrs at cheap rate, so far. In winter on cold nights, I was only getting 1.6 kW per hour net, ie under 6 mph.
I have had to use a total of 49 hrs at the 'day' rate when I used it a lot (yes, I've kept a spreadsheet), 939 hrs at cheap rate, so far. In winter on cold nights, I was only getting 1.6 kW per hour net, ie under 6 mph.
The current transformer measuring the total house electrical load is connected by a data cable to the charger. It's an analogue signal so a twisted pair data cable is good.
This data cable is quite often part of the power cable running to the fuse box.
Without the CT the charging current may be limited.
This data cable is quite often part of the power cable running to the fuse box.
Without the CT the charging current may be limited.
Just turn off load balancing in the app. You don't have to use the CT clamp, but its probably a good idea if you might have a lot of other house load at the same time as charging.
Mine isn't connected FWIW as when my consumer unit was changed, the electrician didn't reconnect it... My car still charges at the full 7kW.
If that doesn't work, its possible the installer hasn't setup the charger to 32A? You should be able to see both settings in the charger configuration in the app.
Mine isn't connected FWIW as when my consumer unit was changed, the electrician didn't reconnect it... My car still charges at the full 7kW.
If that doesn't work, its possible the installer hasn't setup the charger to 32A? You should be able to see both settings in the charger configuration in the app.
Edited by R32 on Tuesday 8th April 09:08
R32 said:
Just turn off load balancing in the app. You don't have to use the CT clamp, but its probably a good idea if you might have a lot of other house load at the same time as charging.
Mine isn't connected FWIW as when my consumer unit was changed, the electrician didn't reconnect it... My car still charges at the full 7kW.
If that doesn't work, its possible the installer hasn't setup the charger to 32A? You should be able to see both settings in the charger configuration in the app.
Max charge current is 32A, according to the details for my charger in the app. The company who installed it will be sending someone out to fix it. Mine isn't connected FWIW as when my consumer unit was changed, the electrician didn't reconnect it... My car still charges at the full 7kW.
If that doesn't work, its possible the installer hasn't setup the charger to 32A? You should be able to see both settings in the charger configuration in the app.
Edited by R32 on Tuesday 8th April 09:08
Thanks for the help everyone, the issue is now all but completely confirmed to be the missing CT clamp.
R32 said:
Just turn off load balancing in the app. You don't have to use the CT clamp, but its probably a good idea if you might have a lot of other house load at the same time as charging.
Mine isn't connected FWIW as when my consumer unit was changed, the electrician didn't reconnect it... My car still charges at the full 7kW.
If that doesn't work, its possible the installer hasn't setup the charger to 32A? You should be able to see both settings in the charger configuration in the app.
A CT clamp may be required by the DNO (Distribution Network Operator) for an EV charger installation, especially if the installation involves load balancing or if the DNO requires monitoring of the property's overall power consumption. This is becoming a much more common stipulation by DNO's these daysMine isn't connected FWIW as when my consumer unit was changed, the electrician didn't reconnect it... My car still charges at the full 7kW.
If that doesn't work, its possible the installer hasn't setup the charger to 32A? You should be able to see both settings in the charger configuration in the app.
Edited by R32 on Tuesday 8th April 09:08
ashenfie said:
A CT clamp may be required by the DNO (Distribution Network Operator) for an EV charger installation, especially if the installation involves load balancing or if the DNO requires monitoring of the property's overall power consumption. This is becoming a much more common stipulation by DNO's these days
It’s absolutely required for any on line DNO (or delegated ENA) authorisation, with the whole house load at no more than 60A, and that’s assuming it’s already a 100A fuse and non looped connection.If you do anything else, you’re into surveys etc.
Don’t turn load balancing off, indeed, don’t go near the installer menu at all unless you know what you’re doing.
The wallbox doesn’t limit the current itself, it sends a signal to the car to tell the charger in the car how much AC it can draw based on its max capacity or less depending on the CT etc. I call it wall box, as technically it’s not a charger, the charger is in the car for AC charging.
Edited by Rough101 on Sunday 13th April 10:25
Just to manage your expectations, with a CT clamp taking readings and passing them back live to the Ohme you will get variable speed charging even at "max".
My Load Limit is set to 80A, and when the house is busy with load (particularly the heat pump) the car will only get 6.4kWh - 6.8kWH even when the overall load isn't close to 80A, so I guess it gently moderates it's draw with the overall load, rather than operating a hard cut-off.
My Load Limit is set to 80A, and when the house is busy with load (particularly the heat pump) the car will only get 6.4kWh - 6.8kWH even when the overall load isn't close to 80A, so I guess it gently moderates it's draw with the overall load, rather than operating a hard cut-off.
Knock_knock said:
Just to manage your expectations, with a CT clamp taking readings and passing them back live to the Ohme you will get variable speed charging even at "max".
My Load Limit is set to 80A, and when the house is busy with load (particularly the heat pump) the car will only get 6.4kWh - 6.8kWH even when the overall load isn't close to 80A, so I guess it gently moderates it's draw with the overall load, rather than operating a hard cut-off.
The DNOs are in most cases installing 80A fuses and if you are drawing 80a then the fuse size is the least of your worries. As you say the car in capacity terms will draw up to 32amps. A 5kw heat pump between 500w-2500w depending on weather (though thats not constant), so 11amp. Now what are the chances of the rest of the house using 37a? Its a big problem when calculating max load and the reg's guidelines majorly over egg it. My house for example ticks along 95% at around 2A mainly because I work from home. My Load Limit is set to 80A, and when the house is busy with load (particularly the heat pump) the car will only get 6.4kWh - 6.8kWH even when the overall load isn't close to 80A, so I guess it gently moderates it's draw with the overall load, rather than operating a hard cut-off.
Edited by ashenfie on Saturday 19th April 11:39
ashenfie said:
The DNOs are in most cases installing 80A fuses and if you are drawing 80a then the fuse size is the least of your worries. As you say the car in capacity terms will draw up to 32amps. A 5kw heat pump between 500w-2500w depending on weather (though thats not constant), so 11amp. Now what are the chances of the rest of the house using 37a? Its a big problem when calculating max load and the reg's guidelines majorly over egg it. My house for example ticks along 95% at around 2A mainly because I work from home.
I have a 10kW electric shower. That pulls 42A, so that alone plus the car charger is already beyond the 60A of my DNO’s supply fuse.Edited by ashenfie on Saturday 19th April 11:39
mikey_b said:
I have a 10kW electric shower. That pulls 42A, so that alone plus the car charger is already beyond the 60A of my DNO’s supply fuse.
That’s what load balancing is for. Even on a house with an SPN supply 100A fuse the DNO usually require load balancing to limit the current during charging to less than 60A, anything more and they’re likely to require a survey.Gassing Station | EV and Alternative Fuels | Top of Page | What's New | My Stuff