Why Tesla's EV charging system won the race to become America's standard
motortrend.com
motortrend.com
I'd love to know what information is "missing" from the J1772 communication protocol, the trade offs on a digital vs analogue "protocol"? Does it require more control circuitry on each side? Are there safety issues with such high power being controlled by a relatively complex microcontroller and protocol? Is the claimed difference even relevant? J1772 has since 2012 allows digital information to be passed using a AC power-line communication standard. J1772 claims to support 240v, so why are they only using numbers showing the "advantage" of the (likely only available in non-residential supplies) 277v compared to 208v? And why aren't the comparing agains the CCS2 standard? Surely that's the most obvious competitor?
The article being so unfailingly positive yet incomplete triggers my "Advert" detector.
That's pretty much the answer to all your questions, it's a different plug standard using other SAE standards for communication.
As to why it won out in the US, pretty much solely due to the fact that Tesla is basically the only national charge network that gives a damn about their charge network. It's a crap shoot for basically every other charge location and the actual coverage is pitiful compared to the Tesla network.
Because J1772 only does AC charging. NACS does both AC charging and DC fast charging, and the AC is more flexible for installation (both 208 and 277 single and split)
I think the author is confusing the DC and AC aspects of NACS. AFAIK, NACS uses the same J1772 analog protocol for AC charging. I don't think it really matters that much, but if you were designing things from scratch today, it might be nice to have things like:
* Plug-and-charge at commercial AC chargers. Nobody has this today.
* Tell the car whether off/mid/peak energy rates apply (at home AC chargers). You could program your car to charge only at off&mid rates, unless the battery is empty, then let the EVSE figure out what rates apply.
* Send state-of-charge from car to charger, to enable smarter load balancing: Several companies make EVSEs that can supply full current when one car is present, but command the first to throttle back to half current when a second car is plugged in. You might want to adjust that split to, say, 75/25 if the new car is near empty.
> J1772 has since 2012 allows digital information to be passed using a AC power-line communication standard.
Ehh... not really. The J1772 analog protocol can tell the car "hey, I'm actually a CCS station, so let's talk CSS digital protocol". But J1772 itself doesn't define any kind of digital protocol.
> the "advantage" of 277v compared to 208v?
The advantage is that if you happen to have "480V 3-phase" service available (which is common in commercial and industrial settings), you can directly attach NACS between one phase and ground (which gives you 277V). With J1772 you need a transformer to step down to "120V 3-phase" (which gives you 208V between two phases). You also get about 30% more power for the same conductor weight, which makes the copper wiring cheaper.
The two common distribution voltages in North America are 277/480 (phase-ground and phase-phase) and 120/208 (phase-ground and phase-phase). We also have 240, which is "split phase" (two conductors 180 degrees apart).
> And why aren't the comparing agains the CCS2 standard? Surely that's the most obvious competitor?
Well, CCS2 is the DC charging "add-on" to J1772. So IMHO it doesn't really make sense to talk about it in the context of AC charging, unless you're trying to "well akshually... gotcha" someone with an obscure technical point.
If you do want compare NACS and CCS2, the biggest one is simply ergonomics: CCS2 is like mini-USB (not even micro), while NACS is lightning/USB-C. CCS2 is heavy, bulky, and sometimes fails to make a good connection. You need to get the alignment just right to insert and apply a lot of force to get the thing locked in. To remove, you again need to throw your back into it. NACS, by contrast, just pops in and out with your finger tips. NACS ports are curved to guide in a slightly misaligned plug. If you haven't tried it yet, you really owe it to yourself to rent a Model 3 for the weekend and supercharge a couple times. The ergonomics are just vastly superior.
Two wires is enough for 208V phase-to-phase from a three phase power source [0]. NACS supports three phase power sources in this configuration.
[0] https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F...
So support for 3 phase definitely isn't an issue for residential use, where you don't really care about the charging speed. And it isn't an issue for public charging because you'll want to use fast DC charging there.
For public charging DC fast chargers are incredibly expensive, whereas a 3 phase AC charger is pretty cheap and effectively the same price as single phase charger. Delivering more power for the same install cost is valuable since it opens more charging use cases for low cost charging.
I think north america is going to regret not having 1st class support for 3 phase charging baked into all electrified vehicles in the long term.
Unless various European systems are weirder than I think they are, I’m not convinced I buy this. For a fleet, you have more than one car charging in a location. So you can connect each car to all three phases, use more complex AC-DC converters, and get a perfectly balanced three phase load for each car. Or you can connect each car to one phase and neutral or to two phases, use simpler AC-DC converters, and get an overall load that is still, statistically, close to balanced. And you can draw just as much total power across all cars in the two-wire configuration as you can in the three-phase configuration. And you use fewer wires and fewer switching elements in your circuit breakers.
It seems to me that the actual advantages of three-phase charging are:
1. A single car on a small three-phase service can charge faster if it uses all three phases.
2. A very long cable with only two current carrying conductors from a three phase service will have an unbalanced average voltage, thus potentially increasing capacitive leakage. (But a split-phase North American 240V system does not have this problem.)
Doubt it.
Long term, I think cars are going to drop AC chargers entire (they're heavy and expensive), and when DCFC are available everywhere there won't be any reason to pay for one in your vehicle. As manufacturers look for places to reduce cost and bring vehicles down market, we will start to see this.
For people who still want it, someone will build a portable 1.4kW DC charger that you can plug into a regular household socket.
Asking everyone to put a high power AC/DC converter in their house or charging infrastructure even for “low” (8-12kW) power stuff is asking a lot for pushing cost around. Long term, you want chargers to be cheap as chips… not more expensive.
Also, not sure if you’ve ever seen even the infrastructure for existing EV chargers… but I’m skeptical that infrastructure will outlast cars in most cases. There’s a ton of maintenance I’ve seen required just on the “dumb” AC chargers. People hit them, they get vandalized, or they just stop working. Making them even more expensive to repair would be the wrong move.
Commercial fleets in the US will use 3 phase for DC. For commercial installations, this is a non-issue [0]. It's more efficient to use DC charging at scale than reside on the vehicle's onboard rectifier.
>I think north america is going to regret not having 1st class support for 3 phase charging baked into all electrified vehicles in the long term.
It's already here... Where are you getting your information?
[0] https://www.eaton.com/content/dam/eaton/products/emobility/e...
There are certainly fleets that need rapid charging throughout the day and they will need expensive DC units. There are many fleets that only need lower speed, longer duration overnight charging at the fleet yard. Native 3 phase with load sharing charging hardware is the lowest cost way to achieve that. No need for expensive labour to move vehicles or power connections overnight, much lower installation cost than even the smallest DC charging hardware, and no need for expensive 400+V DC certified electricians.
If you need charging above that, especially at fleet level, it is cheaper to go with dedicated DC charging like the one's I linked. 48A single phase charging is more than enough for the vast majority of all EV use-cases, even for fleet vehicles. Amazon has the largest EV fleet fielded right now, and that's in the US.
You're complaining about a non-issue. Three phase AC EV charging is a solution in search of a problem.
Maybe so but 3 phase AC is already the minority, and we've barely started the transition to electric cars.
Look at https://www.zap-map.com/live
Orange is 3 phase AC. It's about as popular as single phase, and way less popular than DC.
They just opened a brand new transport hub near me with 100 charging points. All single phase.
I just don't think it's a big deal. I don't think people really care about the difference between 7 kW (takes hours to charge) and 22 kW (takes hours to charge).
Maybe people don't care about the hilarious clumsiness of the plug either; I don't know.
Also three-phase AC is ubiquitous here, you need it to run your sauna stove :D
CCS2 has 7 wires. 5 for 3 phase power (3 phases + ground + neutral) and 2 more for DC.
It a pretty mad design. If you think about it CCS2 requires every single car to lug around a 3 phase battery AC-DC converter instead of just putting it with the chargers. Doesn't make sense.
Two wires is enough for 208V phase-to-phase from a three phase power source [0]. NACS supports three phase power sources in this configuration.
[0] https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F...
3-phase -> DC is easier than single phase. One of the benefits of 3-phase is that power delivered is constant, so you don't need very big capacitors. That's part of the reason nobody makes a DC fast charger bigger than about 20kW.