Saturday, July 18, 2020

My collection is complete(ish)!

I drive an electric car, a Tesla Model S. Generally, I never worry about how or where to charge it. It has a large battery and a long range, ~400 miles, and I have a charging setup in the garage that is where it gets charged nearly all of the time, generally only to about 60% of capacity, because keeping the battery closer to 50% most of the time extends its life, and for daily driving I really only need about 20% of the range, so it tends to oscillate between 40% and 60% full. On long trips I also use Tesla's Supercharger network.

But, just in case, I'd like to ensure that I have the ability to plug it into whatever other sort of connector may be available. The whole collection needed for North American plugs is surprisingly large. And it's technically incomplete because there are a lot more plugs around, but these cover all of the common cases, I think.

The Collection
I'll go through them one by one.  There's one I have that isn't shown, because it's the one built into the car; the Tesla-style plug.  It's available at Tesla Superchargers and destination chargers. But this is about the set of adapters needed.

NEMA 5-15

Also called the North American Type B plug, this is the standard wall outlet plug. It's definitely not what you want to use to charge an electric car, but it can work. I drove a Nissan LEAF for two years with nothing other than a standard wall outlet for charging at home. Everyone has seen this, but here's a picture anyway:

NEMA 5-15, or Type B
The reason this isn't a great plug to charge with is because it's limited to 15A at 120V, which means it only provides at most 1.8 kW.  To charge a 100kWh battery from empty to full (which you never do, and could never actually do for complicated reasons I won't go into, but it's still a useful comparison point) on a NEMA 5-15 outlet would take about 56 hours. To put that another way, assuming 250 Wh/mile is the energy used when driving, each hour of charging nets you 7 miles of range. In practice a little less because there are some losses.0


The TT-30 is a common RV plug ("TT" stands for "Travel Trailer") that delivers 30A, double the NEMA 5-15, but still only at 120V.  So it provides up to 3.6 kW, twice as much as the NEMA 5-15.  So a full 100kWh charge would take about 28 hours, and you get about 15 miles of range for every hour of charging.


NEMA L14-30

The L14 is a plug commonly found on generators.  I actually have an 8kW generator with this plug, so having it is theoretically important for me. If my car were to run out of power reasonably close to home, I should be able to throw my generator in the back of the pickup, run it over to the car and charge the car up enough to get it home. Of course, that should never actually happen, but...

Like the TT-30, the L14-30 delivers up to 30A, but at up to 240V, meaning it can deliver up to 7.2 kW, charging the car from empty in around 14 hours, and delivering about 29 miles of range per hour of charging.

NEMA 6-30 and 6-50

The NEMA 6-series plugs are common in older homes for dryers, ranges and welders. They're no longer allowed by the electrical codes for new installations, because they lack a ground pin, instead making the neutral pin do double duty. Still, they're pretty common. We used a 6-30 when we plugged into a dryer outlet in McCall, Idaho, and the 6-50 when we plug into my brother-in-law's welder outlet.

The 6-30 delivers the same amount of electricity as the L14-30.  The 6-50 delivers up to 50A at 240V which is about as good as it gets outside of dedicated EV charging plugs.  50A @ 240V is 12kW which could theoretically charge a 100 kWh battery in just over 8 hours, and provides 48 miles of range per hour of charging. In practice, the onboard charger in my Model S can only accept 48A @ 240V, 11.5 kW, so unless I'm at a Supercharger, the fastest I could charge from empty to full (if that were possible) is 8.7 hours, gaining 46 miles of range per hour of charging.

NEMA 6-30

NEMA 6-50

NEMA 14-30 and 14-50

The 14-30 and 14-50 are the modern, properly-grounded versions of the 6-30 and 6-50.  They charge at the same rates; 30A @ 240V and 50A @ 240V.  Most RV parks have three outlets at each site: One or more NEMA 5-15s (standard household outlet), a TT-30 and a 14-50. Charging out in the boonies (say, northern Canada) where the Supercharger network isn't available would probably mostly be done at RV parks, so these three are the most useful.
NEMA 14-30

NEMA 14-50

SAE J1772

The J1772 is an EV charging outlet. It can deliver up to 80A @ 240V, which is 19.2 kW.  Were my car's internal charger able to accept that much, the 100kWh charge time would be 5.2 hours, and it would provide 76 miles of range per hour of charging. Of course, as I said above, the car's charger can only accept 48A.  This is the common plug found in most EV charging networks in North America. It's also what I have in my garage, since I originally set my charger up for a Nissan LEAF. In practice my garage charger doesn't seem to like charging faster than 40A; if I set it higher it gets too warm inside and turns itself down to 25A after an hour or so. So I always leave it set at 40A (~9.6 kW).

SAE J1772


The Tesla superchargers use Tesla's proprietary connector, and they work fundamentally differently than the above. The Superchargers provide DC, not AC, electricity, and they contain all of the battery charge controlling circuitry, rather than delegating that work to the car's onboard charger. The v3 Superchargers provide up to 520A @ 480V, which is 250kW.  That's a theoretical charge time of 24 minutes for a 100kWh battery, adding 1000 miles of range for each hour of charging.

The v2 Superchargers (which is what most Superchargers are) are slower, providing up to 312A @ 480V, or 150 kW.

Of course, you don't actually get those charge rates consistently. The Superchargers manage their charge rates based on the temperature and state of charge of your battery, and not all Teslas are capable of taking the maximum rates even when their batteries are near empty and at optimal charging temperature. The most I've seen on my car is 140 kW, which adds 560 miles of range for each hour of charging. But I've never used a version 3 Supercharger.  One is being installed about 20 miles from my home. I'll have to check it out.

1 comment:

My collection is complete(ish)!

I drive an electric car, a Tesla Model S. Generally, I never worry about how or where to charge it. It has a large battery and a long range,...