Second 7kW charger at home - any issues?
Discussion
As the title really - I'm planning on having a second 7kW wall charger installed as about to get a second EV and can get one from work for free as it's my first EV company car so thought it makes sense to.
Is anyone aware of issues with having two installed on normal household mains - 100A main fuse, house just over 2 years old.
I guess I'll find out when the installer comes to survey, but I was intrigued if anyone on here has had any problems with doing this.
Is anyone aware of issues with having two installed on normal household mains - 100A main fuse, house just over 2 years old.
I guess I'll find out when the installer comes to survey, but I was intrigued if anyone on here has had any problems with doing this.
You could get something like this that shares power?
https://www.ctek.com/uk/ev-charging/chargestorm-co...
I don't think you can have two 32A chargers on a 100A domestic circuit, it's just not enough headroom. I'm no expert but it has been discussed before and I thought it was a no no.
A charger like the one I've linked above should do the job fine, it's surely rare when you both need a 10-100% charge over night, 7KW shared should be enough?
https://www.ctek.com/uk/ev-charging/chargestorm-co...
I don't think you can have two 32A chargers on a 100A domestic circuit, it's just not enough headroom. I'm no expert but it has been discussed before and I thought it was a no no.
A charger like the one I've linked above should do the job fine, it's surely rare when you both need a 10-100% charge over night, 7KW shared should be enough?
Agree, don’t foresee needing to charge both cars on a daily basis, as that’d be a lot of miles! It was purely that the option to get a second one installed for free is there. A level of redundancy might be useful if one goes down for some reason too. I guess it could be set to 16A to be more cautious?
There are chargers available that might do 2 outputs and load balance between the 2. Something like this:
https://www.rolecserv.com/ev-products/ZURA
That also has CT Clamps so would base itself off the load being used by the house to slow down as well.
Would need a hefty cable to be installed to cover 2 x 7KW to a single charger though.
https://www.rolecserv.com/ev-products/ZURA
That also has CT Clamps so would base itself off the load being used by the house to slow down as well.
Would need a hefty cable to be installed to cover 2 x 7KW to a single charger though.
As above, myenergi zappi has a grid ct and can be set such that it limits it's contribution towards total incoming house draw.
There are at least 2 houses near me with 2 EV chargers and they will be 100A incoming fuses looking at the ages of the house. How often would you be running 9kw of additional load during the cheap EV tariffs? I guess it could be a problem if intelligent octopus was trying to max charge both cars at 6pm.
I only have 1 EVSE but it's on a second CU running a split pair from Terminal blocks. It has nothing to do with the house CU but collectively they share the 100A head.
There are at least 2 houses near me with 2 EV chargers and they will be 100A incoming fuses looking at the ages of the house. How often would you be running 9kw of additional load during the cheap EV tariffs? I guess it could be a problem if intelligent octopus was trying to max charge both cars at 6pm.
I only have 1 EVSE but it's on a second CU running a split pair from Terminal blocks. It has nothing to do with the house CU but collectively they share the 100A head.
Edited by tvrfan007 on Monday 28th August 17:29
Your DNO will tell you what you can have.
They might grant approval for a second charger but with a combined import limit. Don’t generally assume that with a 100A service fuse you can happily pull 64A + house loads all night with the DNO’s blessing.
Zappi does a good job of group device management (if you have more than one they communicate) and is also very flexible in terms of its CT monitoring if you add a Zappi to an existing unmatched charger. You could get it to monitor the load of the other device and make sure the two combined were under X
I do this with 2 x Zappi with the DNO granting a 22kW allocation for ev charging so I could have 1 charger running at 22kw, both running at 11kw or even install a third and have them running at 7.4kW each, all with DNO approval… but can’t just let them run at max power (assuming I had the cars to do so)
They might grant approval for a second charger but with a combined import limit. Don’t generally assume that with a 100A service fuse you can happily pull 64A + house loads all night with the DNO’s blessing.
Zappi does a good job of group device management (if you have more than one they communicate) and is also very flexible in terms of its CT monitoring if you add a Zappi to an existing unmatched charger. You could get it to monitor the load of the other device and make sure the two combined were under X
I do this with 2 x Zappi with the DNO granting a 22kW allocation for ev charging so I could have 1 charger running at 22kw, both running at 11kw or even install a third and have them running at 7.4kW each, all with DNO approval… but can’t just let them run at max power (assuming I had the cars to do so)
Would the Ctek charger below be an option which as 2 outputs?
https://www.ctek.com/uk/ev-charging/chargestorm-co...
https://www.ctek.com/uk/ev-charging/chargestorm-co...
plfrench said:
Agree, don’t foresee needing to charge both cars on a daily basis, as that’d be a lot of miles! It was purely that the option to get a second one installed for free is there. A level of redundancy might be useful if one goes down for some reason too. I guess it could be set to 16A to be more cautious?
It's about potential capacity though, not operator set capacity. The dno and installer both have to assume maximum capacity can be handled in a safe and practical way.If you just want the free charger (why would you not) a workaround could be to let the installer swap old for new, and then you can privately sell the old removed unit. You can even remove it yourself if needs be to get the new installation to go ahead.
I don't see any real benefit of having a second charger installed in parallel. I'm a great believer in redundancy as I work for live productions.. but in this instance your redundant solution is the granny charger(s), which should be more than good enough short term if there's ever a fault. Or later f you get really desperate a trip to the nearest fast charger. On a temp basis you can surely cope without a home charger?
Sheepshanks said:
TheDeuce said:
The dno and installer both have to assume maximum capacity can be handled in a safe and practical way.
Do they? Even within a house "diversity" - the assumption that not everything will be used at once - is allowed for wiring purposes.I'll see what the installing company have to say - it's not been a no yet and they're aware I've already got another 32A EVSE.
Edited by plfrench on Tuesday 29th August 13:06
There have been a couple of times when I've wondered how close I'm getting to the 100amp limit on a winters evening.
Car charging at 32A, hot tub heating, boiler running, washing machine, tumble drier, oven, lights, gaming pc, tv's, etc etc.
It's got to be up there with the odd kettle or microwave use thrown in, certainly not another 32A's worth of headroom.
Car charging at 32A, hot tub heating, boiler running, washing machine, tumble drier, oven, lights, gaming pc, tv's, etc etc.
It's got to be up there with the odd kettle or microwave use thrown in, certainly not another 32A's worth of headroom.
RobbyJ said:
There have been a couple of times when I've wondered how close I'm getting to the 100amp limit on a winters evening.
Car charging at 32A, hot tub heating, boiler running, washing machine, tumble drier, oven, lights, gaming pc, tv's, etc etc.
It's got to be up there with the odd kettle or microwave use thrown in, certainly not another 32A's worth of headroom.
You can get chargers (maybe it's optional on them all?) with current transformers that link to the incoming supply and they back off the charger if ithings are getting marginal.Car charging at 32A, hot tub heating, boiler running, washing machine, tumble drier, oven, lights, gaming pc, tv's, etc etc.
It's got to be up there with the odd kettle or microwave use thrown in, certainly not another 32A's worth of headroom.
Sheepshanks said:
TheDeuce said:
The dno and installer both have to assume maximum capacity can be handled in a safe and practical way.
Do they? Even within a house "diversity" - the assumption that not everything will be used at once - is allowed for wiring purposes.I see no issues with having two 32a chargers on a 100a fuse, especially if at least one of them is smart enough to monitor the total home consumption and adjust accordingly. There are certainly electricians out there installing multiple chargers in residential properties... https://www.youtube.com/watch?v=eUKmkz8dQWQ
Sheepshanks said:
You can get chargers (maybe it's optional on them all?) with current transformers that link to the incoming supply and they back off the charger if ithings are getting marginal.
My neighbour thought that either their car or charger had developed a fault when it wouldn't initiate charging. It was a winter evening and they had their electric radiators, a double oven and an electric shower running and had no idea what a current clamp/load limiting device was.The chap a few doors up who was better informed was certain he had a 100a incoming fuse but it turned out that was just the housing rating. The fuse inside was actually 60a.
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