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Discussion Starter · #1 ·
I currently have an I3 and am looking into the possibility of a second car at home. This second car is likely to be a Tesla.

One of the first challenges that I have is that the UK power supply to the house is limited by a master fuse of 60A. This limits the house to around 15KW of power.

With the Tesla having such a large battery there are many nights when it is likely to be running for several hours flat out at 7.4KW. Typically the I3 needs around 2 hours to charge with the normal daily use it gets.

Two chargers running at 7.4KW each would very quickly mean I am likely to blow the master fuse if anything else of any significant power is turned on such as a kettle or a hair drier. I am trying to avoid a situation where I am having to make manual choices as to which device I can charge or make use of in the house.

So to address this I have enquired of my power distribution company the possibility of having the supply to the house increased from the current 60A to a higher rating hopefully a 100A but subject to what can be supplied.

My challenge is they have come back and asked for the following specs from the charger's :-

·ENA EREC P28 for control of flicker & voltage fluctuations
·ENA EREC G5/4-1 for control of harmonic voltage distortion
·Charger conforms to BS EN 61000-3-11 & 12.

Has anyone in the UK been through this before and managed to get these documents from any of the manufacturers as I seem to be drawing a lot of blanks currently.
 

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Soul EV & Tesla Model S
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I too asked this question to my electric company. They were very helpful. They gave me a list of necessary upgrades I needed to make and quoted me a 100 A fuse replacement. My brother who is an electrician said that the upgrades were not really necessary. He also said that 60a is not exact and normally the house could use more and not trip the fuse.

My brother suggested I leave as is unless it starts to blow the fuse. He said at this time they would probably change the fuse for free. I haven't yet got the Tesla so it's still all theory.
 

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Discussion Starter · #3 ·
My concern is the overall combined load. For example last night when my wife was cooking dinner and the charger was going we had peaks of 12.5KW without adding in a second car that would be charging as well.

I am hoping that the new Tesla Wall charger will allow me to get upto 40amps which would be 11KW to speed up the charging and make best use of the economy 7 meter.
 

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My concern is the overall combined load. For example last night when my wife was cooking dinner and the charger was going we had peaks of 12.5KW without adding in a second car that would be charging as well.

I am hoping that the new Tesla Wall charger will allow me to get upto 40amps which would be 11KW to speed up the charging and make best use of the economy 7 meter.
If you charged the i3 at 16 amps instead of 32 that would reduce your peak load, and the i3 will always have enough time overnight to refill at 16A.

You won't get 40amps on the Tesla. In Europe, if you have a "single charger" you effectively have a 16amp charger capable of using 3 phases. If you have dual chargers you have a 32amp charger capable of using three phases. At home you only have single phase, so the most you can pull is 32amps. You can however set the car to use less than that.
 

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Soul EV & Tesla Model S
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If you charged the i3 at 16 amps instead of 32 that would reduce your peak load, and the i3 will always have enough time overnight to refill at 16A.

You won't get 40amps on the Tesla. In Europe, if you have a "single charger" you effectively have a 16amp charger capable of using 3 phases. If you have dual chargers you have a 32amp charger capable of using three phases. At home you only have single phase, so the most you can pull is 32amps. You can however set the car to use less than that.
I'm not sure this is correct. Although you can't buy single phase 10kw units off the shelf they can be built. With this you could get the full 40A. Well this is what I was told by Robert at ZCW. Wether you really need one is another question.

I looked at this as I've already had my free unit for the gen 1 leaf. If I get the model S I will be buying/installing the unit at my own cost.
 

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Discussion Starter · #6 ·
Even throttling back the i3 to 16 amps and the Tesla at 32 amps still means I can't have a shower before I go to bed if both cars are charging. With only 7 hours of cheap electric in the night then I am at best going to only be able to had 1/2 a charge a night on the Tesla.
 

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Even throttling back the i3 to 16 amps and the Tesla at 32 amps still means I can't have a shower before I go to bed if both cars are charging. With only 7 hours of cheap electric in the night then I am at best going to only be able to had 1/2 a charge a night on the Tesla.
Economy 7 might not be the cheapest (or most practical) option for you, particularly if you have two EV's and electric shower & cooker....
 

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I'm not sure this is correct. Although you can't buy single phase 10kw units off the shelf they can be built. With this you could get the full 40A. Well this is what I was told by Robert at ZCW. Wether you really need one is another question.

I looked at this as I've already had my free unit for the gen 1 leaf. If I get the model S I will be buying/installing the unit at my own cost.
You're going to change the charger in your car? Or you're going to install a device at home which takes single phase AC and creates 3 phase AC?
 

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Soul EV & Tesla Model S
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You're going to change the charger in your car? Or you're going to install a device at home which takes single phase AC and creates 3 phase AC?
No sorry as I said I'm not 100% on this and you may certainly be more knowledgeable on this than me. I would buy/build a home unit that is 40A single phase. This would give the full 10/11KW to the car. As I understand it the car has a 11KW in built charger as standard. The dual charger option allows 22KW. I know we mostly use the 32A 7.4KW home units but I'm sure that the car will accept 11KW single phase. Am I wrong?
 

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I don't know if I'm reading this right, but have you told the board that you plan to install a "high power charger" and therefore need the supply to your house upgraded? Maybe that's why they are asking the questions? They want to know about this charger.

Surely you are only fitting an EVSE - a supply for the car. It won't generate harmonics in it's own right. It won't cause voltage fluctuations in it's own right. The car might, but that's a different question? I presume all car manufacturers already have to comply with regulations with regard to plugging into domestic mains (?).

Do you have to give a reason for upgrading the house supply? Could you just not say purchasing a second EV, requiring a second EVSE load up to 32A and leave it at that?

Presumably you would still (legally) have to inform the DNO re the second EVSE install - not sure quite how that would work for homebrew. Only ever had the OLEV unit fitted, so all that is done by installer/supplier.

But as Edd says the Tesla 11kW / 22kW is 3 phase, so a moot point.
(Tesla chart says 400V/16A - 400V x 16A X SQRT(3) = 11,085W for a 3 phase supply).
 

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Might be worth looking at some kind of solar system, possibly with battery pack, if you are looking to use that much electricity. You could then charge at different times without having to cram everything in to the Economy 7 period.
 

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The Tesla will only charge at 30A with most home Type 2 chargers.

Suggest you use the charge timers in the cars. You can start the S charging at 12.30am, and the i3 at 3am.

Worse case, you then have a 46A draw at 3am-5am, assuming you need more than 60 miles of charge in the Tesla.

Guessing that there will not be much cooking or hair drying going on at that time in the morning, so you should be ok. I certainly don't have an issue with my 100A supply, despite my place having electric everything - heating, cooking, hot water, car...
 

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Discussion Starter · #13 ·
To make economy 7 pay then you need to be looking at around 40% of your consumption being overnight.

My typical daily consumption with 1 car is around 25KWH a day. Pre EV I was around 15KWH per day.

With a second car and time shifting all the washing/drying to happen overnight then I can easily get to that 40% point. As I also already have PV panels installed then my daytime consumption is already reduced to a lower level so already skews my usage pattern to more overnight.

My request to the DNO was to ask for the power to the house to be increased and they want a reason for this which I said was a second EV hence the reason for them asking for the data about compliance and how much harmonics will be generated.

I am wondering what they do for all the other 32A connections they provide for multiple charging points in Milton Keynes. Especially as the charging point itself is essentially dumb as regards to doing anything with the power.

At the end of the day I would be happy to get two 7KW charging units working and have headroom to be able to do other things in the house like boil a kettle :)

Interesting as to what the differences are between the UK and US chargers as in the US they can feed 80amp 240V to the car on single phase.

chart.jpeg
 

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Discussion Starter · #14 ·
There is the interesting question raised about what is the point of the dual chargers.

If the only time they are of any use is when you are connected to 3 Phase power then the number of times that people will have that ability will be very small. The only public 3 phase is the 43KW fast chargers that are shared with a CHAdeMO which in the US Tesla have an adapter for so you would be better using the CHAdeMO connection.
 

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Do you have an all electric house? An electric shower could cause problems.


EDIT: you do have an electric shower.


You need to get a 100A service.


Even with a 100A service you will need to manage load. Probably best not to take a shower when both cars are charging.





The only public 3 phase is the 43KW fast chargers
There are a few public 22kW 3phase chargers around.
 

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There is the interesting question raised about what is the point of the dual chargers.

If the only time they are of any use is when you are connected to 3 Phase power then the number of times that people will have that ability will be very small. The only public 3 phase is the 43KW fast chargers that are shared with a CHAdeMO which in the US Tesla have an adapter for so you would be better using the CHAdeMO connection.
3 phase is a lot more common in Europe, so it makes sense over there.

You -can- get 3 phase at home, it's just very expensive.
 

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I'm going through the dual chargers option in my head at the moment also. I have 3 x 100 amp phases at home and am still undecided as to whether the dual chargers would ever be needed. Is it really vital to have a fully recharged car by 10PM every night? On the road I can only ever see DC Superchargers and CHAdeMO being used.
 

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Discussion Starter · #18 ·
About once a month I am in the situation of arriving home late and needing to leave early but I would only be able to get a 1/2 charge into the car which isn't enough for the next day.

Hoping there will be a super charger installed somewhere near me in the future to solve that problem.
 
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