NEMA 5-15 vs 14-50 Efficiency

[teknoprep]

I am moving to a new house, and the garage has a NEMA 5-15 outlet where I park. Conveniently, it's also right next to the circuit breaker, which is brand-new and has space to expand.

Considering I only drive 30-40 miles per day, I'm debating whether it's worth it to install a NEMA 14-50 (or other type outlet). I'm guessing it would cost <$500 since it's right next to the breaker, but are there any disadvantages in efficiency to just using the standard plug? I read somewhere that it costs more to use a 5-15 vs 14-50 due to it being less efficient - is this true, and would it end up costing more in the long-run than to just installing the 14-50 now?

 

[LCR1]

It's been a while but the last study I read puts 120v charging around 75% efficiency, while high power 240v is around 93-97%. This was for all EVs, and the tesla runs a lot of systems during charging so there is power going to car constantly that isn't being being put in the battery. Because of this, the longer it takes to charge the more power that goes to systems other than the battery.

Check to see what it takes to get a 14-50 installed. I didn't need any permits so it was less than $50 to do it myself.

 

[teknoprep]

It's been a while but the last study I read puts 120v charging around 75% efficiency, while high power 240v is around 93-97%. This was for all EVs, and the tesla runs a lot of systems during charging so there is power going to car constantly that isn't being being put in the battery. Because of this, the longer it takes to charge the more power that goes to systems other than the battery.

Check to see what it takes to get a 14-50 installed. I didn't need any permits so it was less than $50 to do it myself.

Thanks! That's exactly the info I needed! So it looks like I'd be spending 20% more in power everytime I charge my car, plus it takes 10x as long. This sounds like a no-brainer!

And I'm reading that NEMA 14-50 and 6-50 are essentially the same for Model 3, so maybe it'll save some money by going with 6-50? Or is 14-50 more universal so I should stick with that?

 

[LCR1]

Thanks! That's exactly the info I needed! So it looks like I'd be spending 20% more in power everytime I charge my car, plus it takes 10x as long. This sounds like a no-brainer!

And I'm reading that NEMA 14-50 and 6-50 are essentially the same for Model 3, so maybe it'll save some money by going with 6-50? Or is 14-50 more universal so I should stick with that?

Completely depends on what codes there are in your area, if there are no electrical codes to follow then you can run a 6-50 (three wires total) and save a little money but you'd have to buy the 6-50 adapter for $35. Most places with code require you use 4wire, 14-50 outlets. If you run the 14-50 (4 wires total) you'll spend a little more on cable but don't have to buy the adapter.

Even though there are no electrical inspections or permits where I live, everything I install is 4 wire; the cost is minimal, it future proofs everything, and I don't have to worry about compatibility of things when I buy new appliances or whatever. You said it's right next to the breaker, so running 6/3 (actually 4wires total) should be a negligible difference in running 6/2 wire. And you don't have to worry about upgrading anything in the future, the outlet can then be used for all kinds of things going forward.

 

[doghousePVD]

The difference in cost for a short wire run in trivial (3 wire vs. 4 wire). The 14-50 is more common in residences and campgrounds.

The 6-50 is common in mechanics garages and other places that do welding. My vote, absent any other info, is to go with the 14-50.

I always try dissuade folks from trying to live off a 5-15 (standard Edison). Your average driving is not really relevant, it is your maximum that is important. While most days you arrive home at six with a 30 mile commute, sometimes you have an emergency and have to go to the airport or hospital, get stuck in horrific traffic, or have a wild night on the town and don't get home until after midnight. Yet you still have to go long distance the next morning.

 

[LCR1]

Some things to consider

1) If your area follows NEC 2017 standards and you claim that outlet is used solely for EV charging then you're required to have a GFCI breaker installed, they cost $100. If the breaker/circuit is used for anything other than EV charging you can have a regular breaker. My RV is parked next to the garage, so if anyone ever asks I installed the 14-30 and 14-50 for the RV, or the huge welder I plan on buying in I don't know, never .

Although I do understand the concern because EVs pull a lot of power for a long time; even stoves, dryers, water heaters, welders and RVs cycle off/on. Your oven and dryer aren't running full blast, the elements cycle so it's not a continuous load like a EV charger is. Is one inherently safer than the other? when installed and used properly it makes no difference.

2) Run the 6 gauge copper wire to a 50 amp breaker. You'll have people and electricians tell you since the car/EVSE is only rated at 32A you can get away with a 40amp setup, and you can, but it's a headache and not worth the flexibility loss. You'll have this outlet for as long as you have a car and with the advent of more EVs you never know if a friend needs to borrow an outlet with higher capacity in 5 years. Just run everything rated for 50amp and be done with it, again, not worth skipping on the few bucks.

Something else, but I forgot.

 

[animorph]

My HPWC charges at home show an average of 76% efficiency from TeslaFi. When I charge at my son's house on 120V 12A it shows 69% efficiency. Some would be in very hot conditions but nothing very cold.

Edit: HPWC is 72A for earlier charges and 40A mostly since we got the 3. The numbers above were for my X.

Edit: Some of my charges will be very short, which can be very low efficiency.

 

[ucmndd]

@LCR1 got you covered. Go with the 14-50 with #6 wire and a full 50A breaker . If you’re installing next to your panel it should be very minimal cost ($500 should be max-max if you went with the gold-plated electrician and pull a permit). I did my own in an outdoor RV box right next to my panel for less than $50.

 

[teknoprep]

This is all great info - thank you everyone!

 

[ewoodrick]

I am moving to a new house, and the garage has a NEMA 5-15 outlet where I park. Conveniently, it's also right next to the circuit breaker, which is brand-new and has space to expand.

Considering I only drive 30-40 miles per day, I'm debating whether it's worth it to install a NEMA 14-50 (or other type outlet). I'm guessing it would cost <$500 since it's right next to the breaker, but are there any disadvantages in efficiency to just using the standard plug? I read somewhere that it costs more to use a 5-15 vs 14-50 due to it being less efficient - is this true, and would it end up costing more in the long-run than to just installing the 14-50 now?

Don't worry about the efficiency, it's not that important. $500+ to pay for the plug installation is definitely going to offset it.
At least start with the 120V 15A plug. You can very possible switch it with a 120V 20A plug and get even more at modest cost.

Don't spend money until you know exactly what you need/want.