Installing New Outlet for Any EV

I am going to talk about SAE J1172, as I am most comfortable with that and the Prime uses it.
When the car is plugged into the EVSE, negotiation takes place. (Wikipedia calls the EVSE 'supply equipment')

SAE J1772 - Wikipedia
reads:

• Control Pilot (CP) functions begin
  • supply equipment detects plug-in electric vehicle (PEV)
  • supply equipment indicates to PEV readiness to supply energy
  • PEV ventilation requirements are determined
  • supply equipment current capacity provided to PEV
• PEV commands energy flow
• PEV and supply equipment continuously monitor continuity of safety ground
• charge continues as determined by PEV
• charge may be interrupted by disconnecting the plug from the vehicle

So notice that before current flows, that the EVSE tells the car what Amperage it can provide, then once current flows, the car determines the charging it needs. So your friend's BEV will only get as many amps as your EVSE will provide, and will only request what it needs, doing no damage to either.

The other question, using the 240 volts directly from the receptacle, will just trip the breaker. Which 'solves' that problem.

 

While this sounds reasonable, you probably plug a 5-watt cellphone charger or a 100-watt reading lamp into a 15-amp circuit every day without giving it a second thought. The breaker is intended to protect the wiring from the panel to the outlet, not the device plugged in at the end.

All EVSEs, including the OEM charging cable which comes with the Prime, have their own internal protection. Of course, that could fail but it is unlikely.

The problem with this approach is that the diameter of the wire needed for a 50 amp circuit may be physically too large to fit safely into the terminals of a smaller breaker. Most 20-amp breakers won't accommodate #8 wire. And there is no way to connect #8 wire to a 20-amp outlet without splicing smaller diameter wire as a "pigtail" at the end, something definitely not allowed by code.

To do this "correctly" and in a way that resolves your worries, run the 50-amp circuit to a small sub-panel located near the outlet and install a 20-amp breaker (preferably with GFCI ground fault protection) in the sub-panel. This solves both your safety concern and the wire size problem.

 

Well, there goes @JimboPalmer idea.

 

Hmm, I'll have to go back and refresh my memory on how I did this on my home solar system. Wired for 50A from main panel through production meter and quick-disconnect to subpanel, currently with a 40A breaker on main panel. But before the most recent expansion, I had a 20A breaker there on that heavier wiring. That earlier phase didn't actually have a subpanel, just a single 20A branch coming into the disconnect. But now two active branches (now 20 and 15A breakers) and a third branch for future expansion meet at the added subpanel.

Or did I get lucky by having a breaker line not falling into that 'most' limitation? Thus fitting well into the same approach Jimbo describes. And I did this years before he described it.

This PV system was built in three phases so far, with wiring and module layout set to allow one or two more expansion phases as load increases or plug-in vehicles are added. At each stage, I used the smallest breaker ratings that fit, and upsized as needed when expanding.

 

Bingo!! I've lost count of the number of times I've pointed this out. The breaker is there to protect the wire and the outlet. Tons of people are afraid to plug their 16A L2 EVSE into a 30A or 50A outlet but plug their 1/3A lamp into a 15A outlet all the time.

What am I missing? I thought the idea was to future-proof by having 50A wires and outlet. #12 won't fit into a 20A breaker's terminals any better in a sub panel than a main panel. And a #8 wire might fit in a 20A breaker terminal but it'll be close.

 

One thing to consider is that a lot of EVs have the charge port on the front left, where's our cars have it on the rear right. I'd hate to spend a lot to install a "future proof" outlet, and then have to drape the gigawatt cable across my garage in a few years.

 

I had a 50A breaker added with a NEMA 14-50 outlet. My service panel is old and out of production so you can't even buy breakers for it. Luckily the electrician had a 50A breaker for it.

 

IN reply to post #20, which said: "What happens when his family or friends comes over and wants to charge their EV (max charging rate 6.6 kW+) or plug in an RV?"

I would find it somewhat rude for a visitor to ask for a free charge at my expense. If someone wants to drop by and charge their car at a rate exceeding 6.6kW, it would be cheaper to hand them a $5 bill and point them towards the nearest public charger.

Here's why. The public utility charges me 37 cents per kWh during afternoon/evening hours . If my "guest" is drawing 7 kW that's $2.59 an hour. By the time they fill their 65 kWh battery, I'm down $25. No thanks.

As for the cost of future upgrades... IF my parents were coming to visit in an RV and IF they needed to sleep in it and IF their RV actually needed more than 20 amp on 220V then I could swap in a 50 amp breaker for that short period. Keeping a spare 50 amp breaker on hand will only cost $10.

 

I wouldn't mind but I'm also not paying $0.37/kWh.

 

I wonder why it's so cheap up there?

 

It's not really cheap. It's the TOU BEV rate. From 3 PM to midnight it's max rate of 35 -> 37 cents , every day, all year long. From midnight to 3 PM it's 18 cents (just checked).

 

I just mean vs. $0.54/kWh here, but that's not the BEV rate. The BEV rate is something like $0.43 from 4-9pm. Still the equivalent of $5.59/gallon.

 

Can you sign up for the Prime plan? Only $0.17/kWh off-peak

 

Yeah, but your off hours is from 9 PM to 4PM at 17 cents an hour. That's closer to $2.5 per gallon.

 

For now I'm even less expensive at $0.13 at non-peak because I'm on a grandfathered plan. That will be ending soon.

Our utilities in California got smart. They have to get rate increases approved by the California Public Utilities Commission, which looks at the utility's operational costs and profit margins and gets public comment before approving a rate increase. Our utilities know it's a hard slog getting a rate increase through the PUC, and they'd never get a 30 - 40% increase through, so they hit upon a different plan. They created some new Time-of-Use plans with their new high rates, which sailed through PUC because nobody was on those plans and it wasn't a rate increase because they were optional plans. Everyone just figured they wouldn't pick such an expensive plan. Then, after the approval was over and done the utilities notified customers that their old plans would be terminated and they'd have to pick from one of the new plans that cost 30 - 40% more.

Our insurance companies did a similar thing a few years ago. They're required to get rate increases approved by the Insurance Commissioner with public comment. Since they aren't as successful there as they'd like, they hatched up a new plan: they just automatically quadrupled everybody's deductibles while leaving rates the same. If you wanted to get back to your original deductible you had to pay more, of course. According to them, and the insurance commissioner, this wasn't a rate "increase" since your bill didn't change unless you requested a change.

 

Wrong thread, sorry.