It depends on your needs, and how much gas you're willing to still use.

At 120v, 8 amps is only 960 watts. Over 8 hours, that would be almost 7.7kWh, but you won't actually use that much. For reasons too complicated to go into here, unless you never fully charge your battery, the charger won't run flat-out the entire time. As a back-of-the-envelope calculation, I'd estimate that you'll actually use only about 5kWh of energy in that 8 hours.

And not all of that will go into the battery, because the charger isn't 100% efficient. More like 85%. So you'll typically only put about 4250 Watt-hours into the battery over that 8 hours.

A fairly efficient light EV typically uses around 250 watt hours per mile when driven carefully (no big blasts of acceleration, no major hill climbing). Assuming your PHEV is light (under 3000lb) and you drive gently, your 8 hour 120v charge will give you about 17 miles of all-electric driving.

If it's larger and heavier, your electric range could be much less -- perhaps half to two-thirds that distance.

If that's enough for your daily 2-way commute, no problem. Otherwise you'll need the bigger charger.

Or else you'll want to plan on using gas when the battery runs down.

Actually, I think you'll eventually want the 240v charger anyway. The 120v chargers that come with EVs and PHEVs are really only good for occasional and emergency use, except maybe for the proverbial little old lady who only drives 2 miles to church on Sunday. If you actually expect to do any significant amount of driving on electricity, at least level II charging is pretty much mandatory.

My car uses 450 watthours per mile (mfr specs.). I've only had it for a week or so and as long as I use it around town, the overnight (12 hours) charge at 8 amps is enough. Having a faster charge would be useful if I were making two or more trips away from my house (charging it in between), but that's not my current usage. And, of course, I do use gas when the battery gets low.

I'm not really sure what the question is. If 120v charger meets your current needs and presumably Mitsubishi will sell you240v version next week (or next year), why install it now?

I'm just trying to see if I really need it, considering its cost.

Need vs want.

A higher voltage charger will hopefully charge faster. Same current (maybe) but twice the voltage, hence twice the power. That's really the only reason to get one, charging in, say, 4 hours rather than 8. Mit should be able to tell you the charge time with a 240v unit.

You have to read the specs on your vehicle and the "charger" both. Yes you usually get a faster charge rate with a L2 (240V). The car and the charger negotiate how much current is available/needed. I've built one of these. Hopefully, the 8/12 switch is on the unit and not the car like the dumbasses at Chevrolet did in the later Volts.

Ron, the 8/12 switch is on the unit, and I haven't had time to query the Mitsubishi dealer. The mfr's specs say that the charge time at 12 amps is 8 hours and for 8 amps is 13 hours. Both are for the level 1 (110 volt) charger. Level 2 (240 volt) charges in 3.5 hours, at 30 amps, and Level 3 (CHAdeMO) is 25 minutes (80%). Of course, Level 3 is only for charging on a trip, and probably not too useful, although there is one of these chargers right outside my office building.

A related matter is that my understanding of battery technology is that fast charging is bad for the battery, so why charge faster than necessary? Probably 8/12 amps is not significant.

" fast charging is bad for the battery, "

Depends on the battery type.

Everything else being equal, yeah, charging slower is friendlier for most batteries. But it's not quite that straighforward.

Most batteries can be safely charged (to around 80% SOC) at least as fast as they can be safely discharged. Very fast charging or discharging (in much less than an hour) usually requires active battery temperature management. In other words, lots of cooling. If you can keep the temperature down, and I'm talking about the battery's internal temperature, most of the depreciation from fast charging goes away.

The ability to produce and handle high power is one of the design factors that electrochemists balance when they design batteries. It factors into the design as specific power (power for weight) and power density (power for volume). Other major design factors include specific energy (energy storage for weight), energy density (energy storage for volume), cycle life, and cost.

As with most things, you can't get everything you want. You gotta compromise.

FWIW, some batteries NEED high charge rates for some (usually short) part of the charging cycle. If they're not given those high currents, they'll lose capacity and age prematurely. This is the case with some high power AGM lead batteries. I'm not an electrochemist, so I can't even begin to understand the physics of why this phenomenon exists, just that it does.

I've never seen an EV that L2 charging (or even more aggresive ones) are bad for the battery. Their internal charging circuitry is pretty sophisticated about not overheating things. These are not your cordless drill we're talking about (and even those have pretty robust charging circuits these days).

I would definitely look into why the 12A setting is not working on your charger. Hopefully your outlet is on a 20A circuit, you may want to check the breaker. Theoretically even the lower level of typical household circuit (15A) would be enough for a 12A draw, assuming there isn't anything else plugged in. But much better to have it on a 20A circuit. And it likely is, if I remember the code.

I'm not there right now, but I think all the receptacles in my house are 20 Amp and this one, which is on my front porch, is GF protected.

[QUOTE]And it likely is, if I remember the code.[/QUOTE]

Regular branch circuits in residences don't have any restriction as to the number of receptacles on a circuit.

I'm pretty sure the listing on these EVSEs requires internal ground fault detection so plugging it into a GFCI is OK, but redundant.

When I referred to the code I was talking about whether receptacles had to be 20A or whether they could be 15A. Afterwards I realized there can be 15A receptacle circuits. In fact one potential problem is that people change out the breaker and outlet to 20A type but leave the 14 ga undersized wire in place.

In any case even a 15A circuit should handle the 12A charger if there are no other loads on the circuit.

IIRC, there is an exception whereby you can put a 15A receptacle on a 20A circuit. But not the other way around.

Weed is correct. As long as there is more than one receptacle (duplex counts as two) you can put 15A receptacles on 20A circuit.

I've noticed that many receptacles which are 15A because they don't accept the 20A plug are actually rated at 20A.

They are all rated for 20A if they are listed.

15 amp house receptacles are rated for 20 amp pass through, so they can be used on a circuit with a 20 amp breaker, but are only rated for a 15 amp device being plugged in.

True 20 amp receptacles are rated for a 20 amp device, and one of the flat blades in the plug is shaped like a sideways T so the plug only fits in a 20 amp receptacle. I have a few 20 amp receptacles in my garage and utility area, but I have never purchased a device that used a 20 amp plug.

Bruce

Thanks, Ron and Bruce; you've confirmed what I thought.

>>They are all rated for 20A if they are listed.

Listed where? Can you clarify what this means?

All electrical devices need to be certified by a 3rd party before they can legally be sold and distributed. I think there are various parties that are acceptable certifications and depending on the country you are in, it may vary. The two off the top of my head are UL and CSA. (I'm in Canada)

So basically he's saying if it isn't a cheap illegal import, then it's rated for 20A.

Can I assume that if they have the Leviton or Lutron brand, they are UL listed?

Not necessarily UL, but it will be the appropriate listing for sale in the US or Canada if that's where they are selling the device.

Here's an example from Leviton's website:

https://www.leviton.com/en/products/dds15-bdz

It says that it's CSA, NOM, Bluetooth SIG, FCC, Title 24 Compliant.

Any big known brand is going to have the appropriate certifications. They aren't going to risk the huge fines for selling illegal devices.

So, greg, these are legal in the US even though they don't have the UL listing?

I'm no expert, but I think the CSA listing is acceptable in USA and Canada whereas UL is US only? I could be wrong though.

So the CSA listing is more encompassing.

Depends on what you mean by "electrical devices." For permanently installed devices, listing is part of code compliance.

But as far as I know, there is no law anywhere which requires any plug-connected electrical device to be third-party certified. You can find plenty of cheap dollar-store garbage appliances which either aren't listed, or for which the UL mark is counterfeit.

But we're not talking the "plug connected" device, we're talking about about the receptacle it plugs into. It must be listed, and a 5-15 receptacle is going to be good for 20A of passthrough if it is.

Ron, I have a code question regarding this charger issue. I brought the car home from my vacation home where I had been using it, with the 120 volt charger. I need to install a weather protected receptacle on the side of my house within reach of the car's parking spot. If I were to also install a 240 volt receptacle and the same area, can I use a box large enough for both receptacles and put the 120 volt receptacle on the 120 part of the 240 volt wiring (using a total of 4 12-ga wires, including ground)? The level 2 charger for my car uses 16A. I have an unused 240 volt dryer circuit with dual breakers which I would use.

Don't see why not. If you're using one or the other, you don't even need to run additional wiring. All the L2 chargers I've seen just use 2hots and ground (no 120V).

However, you can still use an MWBC to drive both 120 and 240 loads if you have the handle tied together. It's exception no. 2 to 210.4(C). If you have the handbook they even show a picture of this in exhibit 210.2.

Sorry, but what's an MWBC? A dual breaker? I have to run additional wiring anyway because I'm moving the location of the box (and my current, 120V receptacle is in a weatherproof box, but not one of those with a weatherproof cover).

I have an unused 240 volt dryer circuit with dual breakers which I would use.

A 30 amp breaker? You can't use that if you are running 12 gauge wire and are installing a 20 amp receptacle on it. You need a 20 amp dual breaker.

MWBC = Multi Wire Branch Circuit

Typically, it's where two circuits share a neutral. In this case, I guess it would be two circuits sharing a hot.

If you are running new wiring anyways, why not just run two separate circuits? One for the 120v receptacle and one for the 240v receptacle. That way, it you could use the 120v outlet for something else (if needed) while also charging your car on the 240v outlet.

In fact, you might even consider upping the gauge on the 240v circuit. Maybe your charger right now only needs 20amps, but I'm sure in the future they will get faster and require more power. It may not be much more expensive to just install the thicker wire now.

Greg - you're right, I'm not sure what the dryer breaker is (I haven't looked at it recently), but its wire is 10 gauge and that's what I would use.

You can't put a 120v 20-amp receptacle on a 30 amp breaker.

What are the requirements for the 240v charger? Is it a 30 or 20 amp circuit?

Nope, not two circuits sharing a hot. Right the first time, shared neutral. It's been called that at times, but multiwire branch circuit seems to be the preferred term now. Whatever.

IIRC, a circuit protected at 30 amps would require 30 amp receptacles. Ron is more of a code expert than I am by far.

However, you could use a 30 amp 2-pole breaker to feed a small subpanel, and then break out 20 amp 240 volt and 120 volt circuits from the subpanel. Note that this will require a 4-wire feed (separate neutral and ground) from the main to the subpanel, so if you have an old 3-wire dryer feed cable, that would have to be replaced with a 4-wire cable.

David and Greg are correct. You can't put 15 or 20A receptacles on 30A circuits. Not allowed. Again, I've never seen an L2 charger that cared anything about 120 or Neutral, so two wire (plus ground) hookup is fine.

My local power company just sent me an offer for a $500 rebate if I purchase and install a 240 volt level 2 charger, which now is on sale for $599. Looking at the specs for the Chargepoint brand for residential use, I see that it requires a NEMA 6-50 receptacle on a 40 Amp circuit. I looked up the ampacity for several wire gauges and was amazed how many charts on the internet said 20 Amps for 14 Ga wire! I found a chart which says 15 amps for 14 Ga, and 40 Amps requires 8 Ga; does that seem right to you?

I seem to remember that 20a is 12 gauge. 40a is 8 gauge, unless you're talking cordage. In which case if 3 conductor it goes to 6 gauge.

Your memory coincides with mine!

Resurrecting this thread because my situation is changed, but similar questions apply. I'm selling the "main house" and moving full time to my vacation house. Last year I installed a 120 volt GFCI receptacle nearer my preferred parking area (snow kept sliding off my roof onto the original space!); this is on a dedicated 20A circuit. I'm now thinking about putting in a carport, which will be separated from the house by about 20 feet, so I will run underground cable from the house to the carport. I'll probably put in a sub panel and enough capacity to have two EVs. What should I run to have two at least level 2 chargers, as well as 110 volts for other purposes? Should I wire for a Tesla Supercharger? What would I need?.

Regarding usage, my PHEV, when fully charged overnight, displays between 12 miles and 40 miles available on battery, depending on many things, including temperature and, perhaps, recent usage.