[Rebster]

Both myself and partner are considering ordering EVs in the not too distant future, but not clear what that would mean from a home charging point of view. Would we need two charging points installed or are there any other options available?

 

[MarkAlexHarris]

Hi @Rebster. I had this discussion with an installer earlier in the week. I was told that the majority of domestic houses would be limited to 7.2kW, 30A maximum since this is the (sensible) upper limit with existing wiring and single phase. More would require the 'grid' to install new wiring from the road, which might be possible but would be an additional cost of £k magnitude (unless there was a legitimate reason to argue that the wiring needed replacing anyway - which I have seen in another post somewhere). What was recommended was a dual charger (one box, two plugs) which would charge one vehicle first to 80% before then charging the second vehicle. I mentioned that charging with a limit of 30A would be unlikely to achieve 10% to 100% charging on two cars during the night-time period (I was assuming 2 x long range vehicles). The answer given was to consider whether both cars would return home on low charge every night and it was suggested that this would be unlikely, therefore I was considering an extreme case.

Very interested in other views/experiences ?

 

[Rebster]

Hi @Rebster. I had this discussion with an installer earlier in the week. I was told that the majority of domestic houses would be limited to 7.2kW, 30A maximum since this is the (sensible) upper limit with existing wiring and single phase. More would require the 'grid' to install new wiring from the road, which might be possible but would be an additional cost of £k magnitude (unless there was a legitimate reason to argue that the wiring needed replacing anyway - which I have seen in another post somewhere). What was recommended was a dual charger (one box, two plugs) which would charge one vehicle first to 80% before then charging the second vehicle. I mentioned that charging with a limit of 30A would be unlikely to achieve 10% to 100% charging on two cars during the night-time period (I was assuming 2 x long range vehicles). The answer given was to consider whether both cars would return home on low charge every night and it was suggested that this would be unlikely, therefore I was considering an extreme case.

Very interested in other views/experiences ?

Thanks Mark - do you know which suppliers offer dual chargers? Been struggling to find this online.

 

[peterca]

I wonder whether it would be possible to fit two chargers - one a 30amp and one a 16 amp? I think most houses have a 100 amp mains fuse and I think would take that. OLEV grant is available for two chargers if you have two EVs.

 

[Hilltop Dave]

There was an earlier discussion on this subject at 2 EV household - second charging point, and my post 29 of the thread refers to even earlier discussions about what to do if you only have a 60A supply fuse.

 

[TrevorH]

We have one of each ( a 32amp and a 16amp) and a 100 amp mains fuse. You can get two grants if you have 2 EVs (this includes a PHEV). So doable..key will be what mains fuse you have / can have.

 

[roger davis]

We have 2*32A EVSE's and a 100A main fuse. However one of them is a Zappi, which will throttle it's charge rate if the incoming current hits 100A.

 

[ASM]

Hi @Rebster

Before considering complex solutions, do you actually need two charepoints?

How many miles do you drive each day in each car?

A 10 hour overnight charge will add roughly 70kWh of energy which is 200 - 280 miles of range depending on car efficiency and driving style, and assuming a battery big enough and empty enough to take this much energy.

So with 2 long range BEVs you could charge on alternative nights with one charge point proving you do less than 100 miles of driving in each one each day.

 

[roger davis]

So with 2 long range BEVs you could charge on alternative nights with one charge point proving you do less than 100 miles of driving in each one each day.

This is our issue. We have two short-range PHEV's, each having an EV range of about 40 miles. So in order to run both on battery as much as possible they both need charging every night. Hence our need for two chargepoints.

The funny thing is both cars only charge at 16a, but our next cars will probably charge at 32A. Hence the future proofing.

 

[dk6780]

Given that you can currently get two OLEV grants I'd suggest that two separate charge points are the most flexible answer. If you want to use off-peak charging it would be a pain to have to switch the plug over in the night for those occasions when you need to charge both cars, and even allowing for bigger batteries than required it is best to operate them between 20 and 80% capacity meaning daily charging.
We also have two 32 amp points on a 100 amp incoming fuse with load reduction which has yet to be needed. What other loads do you have that will use at least 36 amps continuously after allowing for diversity that will run at the same time? The fuses don't blow instantly on less than 20% overload so you have to try hard. Currently the DNOs are required to upgrade your supply for either EV or ASHP or GSHP use, so even if your current supply is below 100 amps it shouldn't be a problem.
In reality we charge our cars overnight on Go so apart from the immersion heater and baseload there is nothing else on and we've had no issues in two years.

 

[Rebster]

Hi @Rebster

Before considering complex solutions, do you actually need two charepoints?

How many miles do you drive each day in each car?

A 10 hour overnight charge will add roughly 70kWh of energy which is 200 - 280 miles of range depending on car efficiency and driving style, and assuming a battery big enough and empty enough to take this much energy.

So with 2 long range BEVs you could charge on alternative nights with one charge point proving you do less than 100 miles of driving in each one each day.

At the moment I'm considering all options, including what you've just described. Was just wondering if there's an easy solution to charging two cars at home e.g. a dual charger. Surely this is going to become an increasing problem as EVs become more of the norm.

Not going to lie, I have no idea what fuse I have, what loads I have. So any solution needs to be suitable for a simpleton like me

 

[DragonQ]

There definitely are dual port chargers but they are mostly commercial models, I think.

 

[MarkAlexHarris]

There was an earlier discussion on this subject at 2 EV household - second charging point, and my post 29 of the thread refers to even earlier discussions about what to do if you only have a 60A supply fuse.

Thank you @Hilltop Dave. I've worked back through the forum history. Very helpful. Sounds like I need to take the plunge and speak to the Grid.

 

[MarkAlexHarris]

Thanks Mark - do you know which suppliers offer dual chargers? Been struggling to find this online.

Give me few days and I will come back to you. Waiting on the quote.

 

[MarkAlexHarris]

This is our issue. We have two short-range PHEV's, each having an EV range of about 40 miles. So in order to run both on battery as much as possible they both need charging every night. Hence our need for two chargepoints.

The funny thing is both cars only charge at 16a, but our next cars will probably charge at 32A. Hence the future proofing.

Yes, I'm in the same mindset. In fact I'm trying to future proof for 2x 500 mile vehicles. (Must be coming eventually.)

 

[MarkAlexHarris]

Just a slightly off tangent question. My installer was of the view that this level of charging (100A+ per dwelling) across the greater domestic housing stock was unsustainable on the basis that the street network was not up to it (I know the main Grid thinks it can manage as long as peaks are controlled, but I mean the 'last mile'). He was talking about the Smart City concept of inductive charging at traffic lights and car parks. Is that feasible with the existing city networks ? Thoughts ?

 

[Trevor Larkum]

I think the solution remains - and it was mentioned above - to install two charge points with load limiting (such as a Zappi). They will take care of those few times that both charge points are used at high power at the same time. Job done.

 

[Hilltop Dave]

I think the solution remains - and it was mentioned above - to install two charge points with load limiting (such as a Zappi). They will take care of those few times that both charge points are used at high power at the same time. Job done.

Unless you already have a significant other household electric load, only one of your charge points needs to have the load limiting capability. OK one car may charge a bit slower than the other, but even if you have EV's with big batteries, what is maximum the total mileage the two cars are likely to do in each of two consecutive days? [2 x 7kw x 7 hours (E7 hours) x 3 miles/kWh = 294 miles]

There is concern that if everyone in the street does the same, it would overload the supply network, but by avoiding charging during the winter early evening peak (4.30pm to 8.30pm), Western Power Distribution in their Electric Nation trial http://www.electricnation.org.uk/wp-content/uploads/2019/07/Electric-Nation-Trial-Summary-A4.pdf found that there is sufficient existing spare capacity to support at least 30 chargepoints per 100 houses.

 

[dk6780]

found that there is sufficient existing spare capacity to support at least 30 chargepoints per 100 houses

Which isn't going to go far by 2035 when most cars will be EVs, most houses have at least one car, and we are being encouraged to move to electric powered heat pumps for heating.

 

[Woodulike]

That's why companies like myenergi, the makes of the Zappi, are already involved with trials to test out load balancing controlled by a third party and all grant funded charge points have to be smart chargers.

For your two EVs, most people are able to have two charge points fitted. I have a 100amp fuse and have two chargers. If I run them both at the same time age have two immersion heaters running at night I'm drawing 95 amps. That means it would actually be possible to charge three cars at the same time if needed, but I imagine they would need load balancing for an electrician to be able to fit them.

The main fuse is normal just before your meter and will have the size written on it if you want to check yourself.
Even at 60 amps you would be able to charge two EVs with 2 load balancing charge points.

Unless you cars are parked side by side and you can fit a dual charge point in between them the easier use option is probably 2 separate points. They do restrict where you have to park the car every night.