Charging from socket permanently

[WannabeOwner]

I'm curious as to when 13AMP charging breaks even with Off Peak plus a Wall Charger

4 hours (say) off peak, assume 7 MPH - that's 28 miles (10,000 p.a.) - more than the average consumption ... but it would have to happen evenly - if the user drives 10K p.a., but only one day a week, then most of that will be at Peak rate.

Assuming Wall Charger is £1,000 and Peak Electricity is 40p and off peak 10p so 4 miles at 40-10 = 30p saving - so 7.5p per mile cheaper.

£1,000 / 7,5p = 13,000 miles. Say a payback of 3 years is acceptable that's 11 miles a day

So basically for someone doing 28 + 11 = 40 miles a day average or 14,250 p.a. then Wall Charger would be cheaper.

In practice, given that daily mileage would be "lumpy" it would be less than that.

Also, its debateable whether Off Peak is worthwhile for 13AMP car charging ... Peak Rate will be higher for all other usage, and actualy Off Peak usage will not be anything like as much as with a 7kW charger ...

There are also rates for car charging based on kWh added to the car (rather than a 4-hour window) but I don't know if they are available to 13AMP charging?

 

[Jason71]

Yeah. I mean I love the fact that the car is always warm when I get in but it seems to be quite generous with how long it gives itself and it's often sat there having reached temperature for 20 minutes before we actually leave. If I was running a fan heater to heat a cold shed up to 18 degrees for 20 minutes I expect I'd get through quite a bit of power.

I always do it manually as in turn on climate. if I just want the cabin warm for a trip to work then 5-10 minutes is plenty. even if its icy. Its only if I am road tripping and want to maximise range that I would give it longer to properly warm the battery up.

 

[tdjohn]

The other issue is that the EVSE is heavy, and if the EVSE is pulling on the plug you will end up with a poor connection which is dangerous.

https://shop.tesla.com/en_gb/product/cable-organizer

I got one of these having tried a knock off from ebay.

 

[kelvin 660]

I have a Tesla wall charger that cost £800 to install and I was wondering if it would have been cheaper using a UMC instead?
What I've worked out is that if you do less than 29 miles/day (less in winter) and you charge up every night then you don't need a 7 kWh charger, as you won't save any money. However you will save money if, you do longer trips on consecutive days and also you won't have to plug in every day.

If you use Octopus GO (4hrs) or IO (6hrs), the cheapest charges are;

Charging with the UMC on 4 hours/day off-peak you will get ~ 29 miles/day
Charging with TWC on 4 hours/day off-peak you will get ~108 miles/day
Charging with TWC on 6 hours/day off-peak you will get ~162 miles/day

Looking at TeslaFi, I have used 772.99 kWh on drives over 29 miles. If all were charged at 0.31p/kWh less 0.075p/kWh, it would have cost me an additional £181. That means it will take some 4+ years before the TWC would have paid for itself !

In conclusion, if you don't do many miles, or will be moving house soon, a UMC charger will be your best option.

 

[Adopado]

In conclusion, if you don't do many miles, or will be moving house soon, a UMC charger will be your best option.

*If the UMC is limited to 10A.

 

[WannabeOwner]

would have been cheaper using a UMC instead?

Perhaps worth giving some consideration to the Wear and Tear on the UMC, and the fact that if UMC breaks there is no backup (whereas if Wall Charger breaks you still have UMC).

Wall charger would mean you would charge 3x faster - if ever you needed to (but probably if you needed to you'd not get enough in time anyway and would use a Rapid Charger instead)

Also the need to coil up the UMC wet in the rain if you need to take it with you ... I have mine in the car for emergencies. Never needed it for that purpose so I expect that's overkill ... however I have used it when staying at Relies for the weekend ... would I remember to take it with me if it was not in the car? (Clearly most people won't have my failing on that score!)

But I agree, at "normal UK average mileage", and assuming that isn't "A long trip a couple of days a week", a wall charger looks expensive.

 

[Jason71]

Perhaps worth giving some consideration to the Wear and Tear on the UMC, and the fact that if UMC breaks there is no backup (whereas if Wall Charger breaks you still have UMC).

Wall charger would mean you would charge 3x faster - if ever you needed to (but probably if you needed to you'd not get enough in time anyway and would use a Rapid Charger instead)

Also the need to coil up the UMC wet in the rain if you need to take it with you ... I have mine in the car for emergencies. Never needed it for that purpose so I expect that's overkill ... however I have used it when staying at Relies for the weekend ... would I remember to take it with me if it was not in the car? (Clearly most people won't have my failing on that score!)

But I agree, at "normal UK average mileage", and assuming that isn't "A long trip a couple of days a week", a wall charger looks expensive.

UMC is £180 which compared to what other manufactures charge for OEM UMC's is a bargain (£400+ for Renault) so if its that critical get a spare

 

[spdpsba]

UMC is £180 which compared to what other manufactures charge for OEM UMC's is a bargain (£400+ for Renault) so if its that critical get a spare

I was eligible for some funding and I paid around £400 (including all the costs) to install the wall charger. I understand things are expensive now compared to 2020 but still I think not having a wall charger limits the use of EVs. Yes, makes some financial sense and may be entirely practical if you are not doing that many miles but certain aspects of EV convenience need to be sacrificed if you are just relying on UMC. It is like having a 2 or 3 bedroom house - makes absolute financial sense, definitely no need to downsize, less expensive to maintain and look after but few days in a year you or your kids friends or family members wants to stay then you are bit cramped for space. It doesn’t happen often but still people buy 4-5 bedroom houses. It is something similar to an extent!

 

[yessuz]

If you could install the Commando socket (32 or 16 A) in your garage near the door, then you would get much faster charging rate with you UMC - uo to 7 kw or full 16 A rather than 13A from 3 pin...

any electrician can do it and with labour it should be up to 200 gbp.

So you would have proper charger speeds withour "ugly charger" at much lower price... this is achieved with the commando adaptor which you can purchase from tesla

https://shop.tesla.com/en_ie/product/blue-adapter---16a_32a-

however, I would look at option to install used charger (if new too expensive) in this case and install commando at the same time as the fail-safe

 

[thewishy]

If you're referring to only getting 10 A charging rate from a 13 A plug, this is not loss due to inefficiency - it's just the UMC limiting current draw to 80% plug rating as a safety measure. That 20% is not being wasted. Same as over here in Europe I can only charge at 13 A from a 16 A rated standard Schuko domestic plug. If I simply swapped out a Schuko plug for a blue 16 A commando and swapped out the UMC adaptor accordingly I could draw the full 16 A as there is no such de-rating applied to those sockets.

Charging the battery requires that the BMS and some car electronics are kept active. This consumes approximately 300w.

2.3kw AC - 2000/2300 =13% bms overhead
7.4.kw AC - 7060/7360 = 5% bms overhead
11kw AC 3Ph - 10740/11040 = 3% bms overhead

then charging the cells is about about 7% or so from a 230v source. I've noticed 3 phase with a 415v nominal has a higher efficiency (More or less ideal voltage to feed the batt no need to boost, I guess.)

In my experience it's roughly 20% overhead for UMC. 10% for 7kw. 5% for 11kw.

Payback for the extra 10% efficiency will be quite long if your mileage is low enough to get away with a UMC

 

[Jason71]

I was eligible for some funding and I paid around £400 (including all the costs) to install the wall charger. I understand things are expensive now compared to 2020 but still I think not having a wall charger limits the use of EVs. Yes, makes some financial sense and may be entirely practical if you are not doing that many miles but certain aspects of EV convenience need to be sacrificed if you are just relying on UMC. It is like having a 2 or 3 bedroom house - makes absolute financial sense, definitely no need to downsize, less expensive to maintain and look after but few days in a year you or your kids friends or family members wants to stay then you are bit cramped for space. It doesn’t happen often but still people buy 4-5 bedroom houses. It is something similar to an extent!

I don't disagree. but IF you could not install one due to cost, renting, etc etc, but the ability to charge nightly was critical then getting a spare UMC for backup is not crazy expensive.
Having said that friend of mines broke. He raised a service request ( having tested on mine to be sure it was the UMC) and mobile service brought him a new one in a day or two.

 

[GRiLLA]

If you could install the Commando socket (32 or 16 A) in your garage near the door, then you would get much faster charging rate with you UMC - uo to 7 kw or full 16 A rather than 13A from 3 pin...

any electrician can do it and with labour it should be up to 200 gbp.

So you would have proper charger speeds withour "ugly charger" at much lower price... this is achieved with the commando adaptor which you can purchase from tesla

https://shop.tesla.com/en_ie/product/blue-adapter---16a_32a-

however, I would look at option to install used charger (if new too expensive) in this case and install commando at the same time as the fail-safe

If they are installing a commando socket for EV charging then they will need to fit a pen-fault detection device and Type A RCD, which also means it will need to be a separate circuit to the rest of your house. Electricians need to follow the regs otherwise they don't stay as electricians for long. This is easily going to cost you £500.

 

[Wishmaster]

I have been using an external socket I got fitted 2 months before I took delivery,I told the it for charging a tesla and they said it will be fine.

So far 2 Months most of my charging is at home with no issue.