Difference in installing a 32 or 40 amp level 2 charger?

[AKgrampy]

I was thinking:
110 & 12 amps will charge 1.32 KW/h
Give up some to heat loss, and call it 1.2 KW/h
You said you had 13 hours to charge / night. So you can recover. 15.6kwh recovered each night.
Over 7 nights that’s 109 kwh recovered per week.
That’s about 120% of my extended range battery, which SHOULD get 270 miles at 100%. So that SHOULD be 320ish miles of driving / week just from a 110 socket. Even at colder temps, should be 240ish.
You said you need 240 miles for commute. So 110 socket should be doable.
Yes your SOC will decrease slowly through the week but will pick back up when you’re not commuting on the weekend.

An issue to be aware of is preconditioning with the 110 socket. If I read things correctly precondition of batteries and the cabin may drain the HVB (if it works at all - read this in users manual.) so if you precondition or heat cabin you will lose range. Someone with experience may chime in here. Finally do not wire your circuit on what you intend to use - wire it as applicable code requires - it will not cost that much more and peace of mind is priceless.

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[TheCats]

Think about convenience so that there isn't a disincentive to plug in. I have a ChargePoint CT4000, with the nice retracting cables. That's overkill for most users, but keeping the cord off of the ground makes it more pleasant to use. I even installed a wall-mounted J1772 holder, a blank socket, so that my wife wouldn't have to walk the extra two steps to return the cable to the EVSE pillar.

I charge at 24 amps because it's (very slightly) more efficient. I expected that I would bump it up to 30 amps when needed, but I've never need to. There have been times after returning from a road trip where charging to my daily-use 80% setting didn't complete until morning, which is just about right for never being concerned.

 

[dbsb3233]

Remember that an EVSE will probably be the most stressed electrical device and circuit in your home. Unlike an EVSE, devices like ovens, dryers, and A/C units rarely run for 8+ continuous hours at a time (longer use = more heat = more degradation). And their cords are hardly ever moved once installed (like an EVSE is). And they're hardly ever unplugged (frequent plugging in/unplugging gradually weakens the outlet contacts).

That's not to say that the minimum specs for an EVSE aren't safe. But if there's ever a good case for being overly caution and over-engineering the circuit, outlet, and cords, it's an EVSE.

 

[RickMachE]

Ok thanks for all the info guys. I figured out that I do have room in my sub panel to put in a 14-50 outlet. With the Ford plug. Do I need a 50 amp breaker or can I use a 30 or a 40?

See post #25. I attached the exact requirements from Ford...

 

[dtbaker61]

I have a ChargePoint unit hardwired to a 50 amp circuit breaker. I charge at 9.67 KWH in that configuration.

your breaker, charger, and the wiring may be capable of that.... but I'm pretty sure the MME can only accept 32amps from single phase 240vAC.... that's 7.68 kW

 

[dbsb3233]

your breaker, charger, and the wiring may be capable of that.... but I'm pretty sure the MME can only accept 32amps from single phase 240vAC.... that's 7.68 kW

Maybe I'm missing what you're saying, but for L2 the MME can handle up to 48A 240V (like the Ford connected charger). 11.5 kW.

 

[dtbaker61]

Maybe I'm missing what you're saying, but for L2 the MME can handle up to 48A 240V (like the Ford connected charger). 11.5 kW.

I believe that is only true with 3-phase 240v
1-phase 240v is limited to 7.7kW

 

[AKgrampy]

I believe that is only true with 3-phase 240v
1-phase 240v is limited to 7.7kW

What limits the current - the MME?

 

[timbop]

For a 220 line or 240 what breaker do I need. 30 amp?

The connector is a NEMA 14-50, which is only for 40A and 50A circuits. Because the car is constantly drawing power for hours the circuit has to actually be rated for more than you draw. So, for a 32A charger you need a 40A circuit, and for a 40A charger a 50A circuit. If you did go with a 24A EVSE then yes you would only need a 30A circuit, but I would still recommend having the electrician run wire heavy enough to handle at least 40A. It is easy and fairly cheap to replace the outlet and the breaker, but running the wire is often the time consuming and expensive part of the job

 

[timbop]

Ok thanks for all the info guys. I figured out that I do have room in my sub panel to put in a 14-50 outlet. With the Ford plug. Do I need a 50 amp breaker or can I use a 30 or a 40?

40 or 50 only for a nema 14-50 socket

You need a 50 Amp breaker, as a 14-50 calls for a 50 Amp circuit. The EVSE will only draw 40 amps, as the circuit needs to be sized 125% over by some code of some sort...I think it's a national code...

correct about the 125%, but you are allowed to put a 14-50 on a 40A circuit

6 gauge with 14-50 outlet and 40 amp should suffice. This is only for MME. I guess the breaker 40 or 50 doesn’t matter. I can use either

yes, with 6 ga copper you can use a 40A or 50A breaker.

 

[Maquis]

I believe that is only true with 3-phase 240v
1-phase 240v is limited to 7.7kW

Not correct. The MME can charge at up to 48A, 240V which is 11.5 KW (gross input).
The US MME will only accept single phase L2, European version can do 3 phase (Based on what those guys have posted on here).

 

[timbop]

I believe that is only true with 3-phase 240v
1-phase 240v is limited to 7.7kW

no. The max is 11.5kw on standard residential service 240VAC circuit in north america

 

[delacruz.c5d]

Not correct. The MME can charge at up to 40A, 240V which is 9.6 KW (gross input).
The US MME will only accept single phase L2, European version can do 3 phase (Based on what those guys have posted on here).

The limit isn't 40A. I'm not so sure what the upper limit is, but I charge my car at 240V/48A on a 60A circuit. It's roughly 11.2KW (roughly 250W are lost somewhere from the EVSE to the car in the cable)

Graphical proof:

I wonder if anyone has tried putting a MME on a 240V 70A or 80A EVSE...that would be something, but again, the gain at that point would be minimal, but would be an interesting academic discussion.

One more thing, and I'm sure we've all heard the horror stories, but there is a safety component to a hardwire install vs. a receptacle. I know I sound like an overly safety cautious <insertWhateverYouWantHere>, but I've seen some horrific failures of high voltage and amperage plugs. If you leave it a plugged EVSE plugged in all of the time, and make sure there isn't a ton of vibration or moving around of the plug and wires in the receptacle, then it should be fine. But when you start unplugging and plugging in things a lot in those...that's when failures happen...melted components and plugs and stuff. Real nasty.

Again, in my situ, I wanted a permanent EVSE in my house, I was already going to have an electrician swap a breaker, and run new cables, so having them hardwire the EVSE was a minor cost adder (if anything at all), and in my opinion, a safer install.

 

[RickMachE]

Not correct. The MME can charge at up to 40A, 240V which is 9.6 KW (gross input).

Maybe I'm missing what you're saying, but for L2 the MME can handle up to 48A 240V (like the Ford connected charger). 11.5 kW.

Correct, 48amps, which is 11.52KW. My house varies on the V, seen as high as 248 or 249, so closer to 11.9KW.

I just ran it at 48amps, and it maxed out at 11.27Kw.

 

[dml105]

Oy, this thread!

Ask an electrician. Not the internet.

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