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Charging off Mains - long term

Mikeoneuk85

Member
Oct 13, 2019
57
12
Droitwich Spa
I’ve just had Pod Point visit but the installation has now been cancelled as my property requires authorisation from D&O for approval as my electrical line is shared between myself and my neighbour. Potentially this may cost several thousand pounds to sort out the re-routing of power cables for myself and my neighbour.

I was just wondering if i could get by without a EV charger and run it off my mains? My situation is as follows:-

Model 3 SR+
70mile commute a day
I can charge off my mains for 12 hours a day so adding roughly 100-120 miles a day.

My concern is colder weather which will impact range loss. Maybe i could do the occasional supercharge when needed but wouldn't want to have to do this on a daily basis.

Any thoughts and is it safe to run off mains electric long term?

Any info would be much appreciated.
 

tsh2

Member
Aug 27, 2019
274
71
Cambridge, UK
Long term battery management is controversial, but I think charging at 3kW is fairly optimal for battery life. Doing an occasional warm supercharge might have some advantages. The 13A plug (and specifically its fuse) will be the weak point. Plan for this overheating, and make sure there is no potential fuel for a fire.

You can pre-warm in the morning on mains, that should help to offset the cold weather impact.
 

Adopado

Active Member
Aug 19, 2019
3,247
2,409
Scotland
I’ve just had Pod Point visit but the installation has now been cancelled as my property requires authorisation from D&O for approval as my electrical line is shared between myself and my neighbour. Potentially this may cost several thousand pounds to sort out the re-routing of power cables for myself and my neighbour.

I was just wondering if i could get by without a EV charger and run it off my mains? My situation is as follows:-

Model 3 SR+
70mile commute a day
I can charge off my mains for 12 hours a day so adding roughly 100-120 miles a day.

My concern is colder weather which will impact range loss. Maybe i could do the occasional supercharge when needed but wouldn't want to have to do this on a daily basis.

You can certainly do it. Are you allowed to use 16amps (commando)? If so that would be even better but so long as you have the time available to charge there's no reason you can't use a 3 pin plug but that is limited to 10amps. The issue to consider is using the supplied UMC charger. In poor weather that needs some waterproof cover and it's also something that you would normally want to have in the boot for emergency use. That then means manhandling a length of wet horrible cable in the morning. Best to buy a Tesla or 3rd party additional UMC that you can dedicate to home charging, so that's extra cost.
 

Adopado

Active Member
Aug 19, 2019
3,247
2,409
Scotland
Long term battery management is controversial, but I think charging at 3kW is fairly optimal for battery life. Doing an occasional warm supercharge might have some advantages. The 13A plug (and specifically its fuse) will be the weak point. Plan for this overheating, and make sure there is no potential fuel for a fire.

You can pre-warm in the morning on mains, that should help to offset the cold weather impact.

Though I have only charged a few times with the 3 pin plug I never had any issues with unduly hot plug/socket/cable (warm but not hot). No doubt the 10 amp limit is intended to keep things within spec. Definitely good advice to check everything is safe and up to snuff though!
 

WannabeOwner

Well-Known Member
Nov 2, 2015
5,758
2,893
Suffolk, UK
Not yet, might be in a years time as its in the pipeline.

No 13 AMp sockets lying around outside near the parking area that you can purloin? :)

70 miles @ 4 miles / kWh = 17.5 kWh minimum.

70 miles should be around 8 hours @ 13 AMP, for Model 3. So "probably ok" in 12 hours in bad weather. Possibly "good enough" that you could make up any weekdays that fail to replenish totally at the weekend (when not heading off for the weekend :) )

My understanding is that 13 AMP is not as efficient as 7kW, so your "running cost" may increase somewhat compared to Wall Charger ... but still be miles cheaper than Petrol.

I agree with the idea of Commando. Can't see there will be any restriction on your Local Sparky installing that, and if you are worried about Load you could either install 16 AMP or install 32AMp and dial down the AMPs when charging ... but realistically if you schedule the car to charge in the middle of the night, at 32AMP or 7kW, are you and your neighbour going be taking hot showers :p or doing a spot of arc welding :rolleyes: ?
 

TM3PTN

Member
Sep 8, 2019
203
95
Bolton
I had to use the 3-pin plug when I first got my machine - had no issues at all aside from the slow charging.

I have had a commando socket installed by a local sparky a few days ago, and bought a 32A adapter from Tesla. I'm now getting 7KW which is roughly 28mi/hr. I can dial the Amps up or down as I see fit and if i think there is something not quite right. However, I have had no reason to turn it down from 32A for the past week.

Regarding the thought id taking the UMC with you everywhere - you get a type 2 cable in the car which I keep on me and IF I am in the position where I need to charge, I can connect to any EV charger close by. I keep the UMC in a locked box that my commando socket is installed in, and would only really take it with me if I was away overnight and needed to plug in at a 3-pin away from home.

Re. heat - as mentioned above, no issues. It warms up as expected (it is heat passing through the wire after all), but it is designed with safety in mind so nothing to worry about.
 
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Glan gluaisne

Supporting Member
Sep 11, 2019
2,782
2,684
UK
For the first year or so that I owned my Prius Plug in I charged it twice a day using the 10 A granny lead (I know the charging time was a lot less than a Tesla, but it was long enough to make a plug warm up a bit). Never had a problem in doing this, but it's worth making sure that the circuit you connect the granny lead to is in good condition, as a 10 A continuous load can make a 13 A plug/outlet run a little bit warm.

Best bet would be to see if you can get a 16 A commando outlet installed, as in my experience commando lugs are much better at handling fairly high continuous loads than a 13 A outlet/plug.
 
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Yev000

Active Member
May 3, 2019
1,210
783
Knaphill
Everyone recommending commando install are missing the point. There is a reason a dedicated charger requires a separate cable. If you can't install a charger then you can't really install a commando socket for the same reasons. It's not some kind of magical solution. It's just cheaper.

As for 3pin charging. You'll be fine.

I got SR+ charging at work with a 45 mile round trip commute. Over the 8-9 hours I spend at work I get more back than I use even now during winter and not driving efficiently (I average 320 Wh/m)

So your car will definitely charge fine overnight.

The only issues would be:

1. The ring the socket you use is on might not be great and the cable might get warm. Which could be a fire hazard, especially if you use that ring for other stuff, like running a heater.
2. The UMC potentially wearing over the years and in the sun and rain....
 
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thorfun

Member
Oct 16, 2019
46
27
London
had a Jaguar I-Pace for 3 months before I sent it back for a refund. I'm currently in rented accommodation so I couldn't get a charger installed so I was charging it with a 3-pin plug from a socket running under the garage door. never had any issues and so is definitely possible.
I do work from home a lot though so my daily range usage was mostly the school run and a few other shortish journeys.
 

Glan gluaisne

Supporting Member
Sep 11, 2019
2,782
2,684
UK
It also doesn't require permission from DNO (as I understand it)

Hit the nail on the head.

No problem at all installing a 16 A commando as long as the total load on the supply, allowing for diversity, can accept an additional 16 A. The chances are it probably can, and anyway, it's not hard to sort things so that the total load is limited so that it does remain inside the supply capacity.
 
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Jonslatt

Member
Aug 31, 2019
174
130
Malvern, UK
Jumping in a little late here so I apologise. I also share a mains feed with a neighbour. Comes off the pole and then split to go to my consumer unit and their’s. We both have a DNO 60A fuse just prior to the consumer unit and meter.

Personally I can’t see the issue and why you have to get the power rerouted. Check what fuse you have. If you decide to use half of you 60A capacity charging your car then that is no different to your neighbour having a couple of electric fires going all night or a 32A supply for a hot tub.

I had my Type 2 socket installed by Polar 3yrs ago when I had a PHEV and there was no mention of external supply. All the installer was interested in was that the consumer unit was reasonably new, there was room to put a dedicated circuit in and that there was proper earthing.

Would maybe contact another installer such as Polar and see if they say the same thing.
 

VanillaAir_UK

Supporting Member
Jun 17, 2019
7,147
4,669
Surrey, UK
Would a 16A/3kW Mode 3 connector still require DNO permission? Would give a dedicated type 2 connection that may also benefit from OLEV grant. Or a 32A capable Mode 3 charge connector dialed back to whatever the DNO would approve?
 

Fredneck

Member
Nov 8, 2019
478
-32
Pennsylvania
I’ve just had Pod Point visit but the installation has now been cancelled as my property requires authorisation from D&O for approval as my electrical line is shared between myself and my neighbour. Potentially this may cost several thousand pounds to sort out the re-routing of power cables for myself and my neighbour.

I was just wondering if i could get by without a EV charger and run it off my mains? My situation is as follows:-

Model 3 SR+
70mile commute a day
I can charge off my mains for 12 hours a day so adding roughly 100-120 miles a day.

My concern is colder weather which will impact range loss. Maybe i could do the occasional supercharge when needed but wouldn't want to have to do this on a daily basis.

Any thoughts and is it safe to run off mains electric long term?

Any info would be much appreciated.

There is no indication that any charging is harmful to the life of the battery... well, anymore than any other charging that is. Certainly the slower charging is not going to be any worse than faster charging. You are lucky that you get the rate you do. I'm in the US were my model X gets about 3 miles per hour off the mains circuit. lol

I don't know that freezing weather impacts charging in the way you are thinking. It won't slow the charging rate from the few kW you are getting now. Actually, I'm not entirely clear on just how it will reduce the range. Does it require more kWh from the battery to drive the same distance? Or does it simply reduce the kWh capacity of the battery? Or maybe it reduces the efficiency of the battery in recovering the kWh you have put into it?

If it simply reduces the kWh capacity of the battery that won't impact your charging times at all.
 

Daverh

Member
Jul 7, 2019
273
187
Newcastle
Does it require more kWh from the battery to drive the same distance?

My understanding of the OPs situation is that they have to use 17.5KWh for their daily commute (70miles at 4miles/KHh) and can replenish ~30KWh overnight (2.5KW * 12hours assuming charging at 3KW isn't all that efficient).

Going into winter, the 4miles/KWh might change to 3miles/KWh meaning the commute would consume 23KWh*

@Mikeoneuk85 I think you'll be ok if you're charging for 12hours every night, not taking too many detours on the way home.
If you can replenish more on weekends then even better and recommend that you pre-heat your car in the mornings. Your car might not charge while doing that but it'll take some of the strain off your battery.

*this is all based on rough maths so take it with a pinch of salt
 

nufan

Member
Nov 6, 2019
106
91
UK
Apologies if this is a bit thread-hijacky in anyway - but with talk of commando installs above it may be okay.

For either a 16A or 32A commando install by a local spark - does it invoke the earth-rod/Type B RCD regs if they know it is for an EV? If so - and reading into the above, such things aren’t being done here - what do the sparks get told it’s being installed for that’s plausible for the current? Or don’t the non-specialised sparks care/know?

I have a (narrow unusable) garage around a meter from where my Xmas M3’s charge-point would be, and would be happy to use a commando in there with the UMC (after checking the 2005 new build’s circuit was good for it) for a few months before maybe getting something better (when A2 lead times come down perhaps) - but can commandos be installed without the above if it’s transparent it’s for an EV?

Thanks for any advice (and thanks regular UK/Ireland section posters: a lot of the advice you’ve put on the forum I readily slurped up and it greatly contributed to my decision to buy).
 
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LukeT

Member
Apr 9, 2019
729
335
UK
We have been limited to 16A commando at home for the 3 months and 7k miles we've had our Model S. Our socket pre-dated the EV so not sure the regs. However I can say that even with the S's higher per mile consumption I think your commute mileage and timing would be OK with a 16A socket. 3.8kw for 12 hours is 45kwh a night, so unless you have two big days on the trot you'd be bringing it back up to whatever your normal "full charge" was within 2 nights.

I would look into installing a 16A (or 32A if that's a goer) commando socket if regs allows that but not a proper charge point. Assuming a 16A draw here isn't going to get you and neighbour combined to a troublesome current of course, but that seems unlikely in the night time.
 

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