I hope every one of you in the U.S. and your family and friends have a happy Thanksgiving. -Jeff

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By George S. Bower


Answer: Level 3 charging is one level higher than level 2 charging. Level 2 Charging is AC while level 3 is DC.

Right?

Wrong.

According to the SAE, level 3 charging doesn’t imply DC. It can be either AC or DC.

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“Levels” are indicative of the charging power. The higher the level the higher the power whether it is AC or DC.

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Most people refer to AC EVSE’s (Electric Vehicle Service equipment) as “chargers” but technically they are not chargers.

The charger is actually on board the vehicle. The on-board vehicle charger converts AC current to DC current since electric vehicle batteries are DC. The EVSE is the little box on the wall of your garage (generally 240 volts), or the portable unit that lives in the trunk of your car (generally 120 volts).

These EVSEs are an intermediary between your vehicle and the outlet in your home. The EVSE “talks” to your car and determines things such as what the maximum charging power the car will take and whether there is proper grounding.

Getting back to charging levels, there are no SAE level 3 charging specifications defined. Level 3 is TBD (to be determined).
The following SAE chart is a great reference for the details of all the different AC and DC charging levels.

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The maximum power level for each level is summarized in the following chart.

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AC chargers generally use household AC power (either 120 volt or 240 volt). Level 1 AC is 120 volt and level 2 is 240 volt. The maximum power you can get with a level 1 charger is 1.9 kilowats. That is the power you will get from your portable 120-volt AC EVSE. It is set by the maximum current available out of a 20 amp 120-volt wall outlet.

Stepping up to level 2 AC charging, we are at 240 volts and a maximum of 19.4 kw which corresponds to 80 amps. Most plug-in hybrids will accept level 1 or level 2 AC – not level 3.

SEE ALSO: Dear Elon Musk: Your Wireless Charging Solution is Here ​

The Chevy Volt’s AC on-board charger is 3.3 kw level 2. The Chevy Spark EV’s level 2 charger is also 3.3 kw while the Nissan Leaf is 6.6 kw. Note that these vehicles are not pushing to the high end of level 2. The high end of AC Level 2 (19.2 kw) is usually for a pure battery electric vehicle like a Tesla.

There is a level 3 AC category which would be higher than the level 2 maximum of 19.2 kw but this category is currently undefined.

DC chargers do not reside in the vehicle as AC chargers do. The charger is contained in the large cabinet to which the charging cord is attached. Level 1 DC goes to a maximum of 36 kw. Level 2 DC goes to a maximum of 90 kw.

Currently level 2 DC is the highest level defined by SAE specification at 90 kw. Anything higher than 90 kw falls into level 3 which is TBD. However the preliminary upper limit is 240 kw.

That’s a lot of power.

What vehicles have the highest charging power capability?

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Tesla holds the lead in high power charging at 120 kw. However some of the earlier Tesla Model S cars can only take around 90-100 kw. These are known as “a” battery cars. Model S examples that can take the full 120 kw are “b” battery cars. The “a” and “b” ratings can be found on the battery pack behind the front wheel of the car (take note also if you are planning to buy a used one).

Tesla’s lead in high power charging is being challenged however. Audi has announced 150-kw charging and aligned itself with some other German manufacturers to install a super charging network in the United States. The group is called the “Charging Interface Initiative Association” (CharIN).

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Audi has announced the e-tron Quatro concept that will enter production in 2018. This will be Audi’s Tesla competitor with high power all electric front and rear wheel motors, competitive range with the Tesla, acceleration competitive with Tesla and interior room of an SUV.

This article appears also at Hybridcars.com

 

Nice article, Jeff. I was one of those who confused the fast DC charge as Level 3. But I know that the 2017 Chevy Bolt EV will be the first GM production vehicle with fast DC charge as a standard feature, but until GM releases the production specifications, we may only guess how much power it can charge per hour.

I had posted before that some of the EVSE manufacturers, especifically EMW, will also manufacture DC chargers. They have 25 kW chargers as kits or fully assembled units, and they also have the CHAdeMO interface for the Nissan Leaf. Read more here:
http://www.emotorwerks.com/index.php/dc-charging-systems

They have written that they are working on the SAE DCFC interface and will announce when available. So a EV fan who owns two BEVs will probably buy such a set to charge faster at home, and only use AC as an opportunity charging method.

Feliz Dia de Acción de Gracias!

Raymond

 

Off-topic but related to GM:

Cadillac's Camera Mirror wins Popular Science's "Best of What's New" award -
http://gmauthority.com/blog/2015/11/cadillacs-rear-camera-mirror-attains-2015-best-of-whats-new-award-from-popular-science/
http://media.cadillac.com/media/us/en/cadillac/news.detail.html/content/Pages/news/us/en/2015/nov/1118-mirror.html

Some of the forum members asked if the external mirrors could be replaced with cameras and screens. Cadillca did this with the main rear view mirror. The exteriors will come soon.

Raymond

 

Great article and good to see that there are more long term plans in place for EV infrastructure. These Level 3 standards need to be completed quickly. There are many jurisdictions that are concerned about shifting charging standards and this is holding back some of the installation of charging infrastructure. Many jurisdictions are worried about installing a charging infrastructure only to be obsolete a several years down the road.

 

I was having a discussion with someone about SAE Combo/CCS. His impression was that CCS chargers weren't capable of charging above 50 kW. This is obviously not correct, but it appears that there are no commercial CCS chargers currently available in North America that exceed 50 kW.

This was in the context of discussing charging speed for the Bolt, which is claimed to be 80% (from 0%? 10%?) in 45 minutes. Assuming the Bolt has a 55-60 kWh battery, and is able to accept 50 kW throughout the charge without tapering until after 80%, it seems like it could charge to 80% in 45 minutes at 50 kW.

 

Happy Thanksgiving Day to all!

Excellent article, Jeff. A little nit to pick: the 2016 Volt has a 3.6 kW charger, probably to allow reasonable charge times overnight for the larger capacity battery.

Warmer temps today here on Long Island, allowing more EV miles and smiles when driving to what will be a great meal and enjoyable company.

Everyone enjoy the day...

 

Good article George and Jeff. These SAE standards need to be finalized at some point or we will have different standards for every country! Oops. Too late.

One day the Betamax vs VHS vs DVD will work itself out. Oops. Streaming took over.

Point is, the car manufacturer's vendors control this more than anyone. Eventually, it will work itself out when one is found to be superior. Like srreaming video.

I'm thinking wireless.

 

Loboc :
Good article George and Jeff. These SAE standards need to be finalized at some point or we will have different standards for every country! Oops. Too late.


One day the Betamax vs VHS vs DVD will work itself out. Oops. Streaming took over.


Point is, the car manufacturer’s vendors control this more than anyone. Eventually, it will work itself out when one is found to be superior. Like srreaming video.


I’m thinking wireless.
I agree about a wireless standard. I believe there is one being tested now (WIP or Work in Progress), and when that standard is set, the manufacturers of 2017 and future BEVs (maybe the EREVs too) will offer the receiver as a optional feature. Then the buyer can choose a transmitter, just like the EVSE is chosen and bought now.

Wireless charging will also allow more opportunity charging, and maybe get funded to be installed on new superhighways, where Federal funds should be applied (not for H2 fuelishness).

Raymond

 

Raymondjram ,

Thanks Raymond. George S. Bower wrote this one.

Y Feliz Acción de Gracias a usted. Que Jesús los bendiga.

 

Happy Thanksgiving everyone!!

 

I haven't been following Tesla as they are beyond my price range. Currently they use the most powerful charging interface out there. Are there any reports to battery degradation related to frequent use of their high powered Superchargers?

Fast charging is essential for the adoption of battery EVs, so higher charging rates are good, but one thing I've learned as an engineer is you rarely get something for nothing, there's always some disadvantages that have to be taken into consideration. If degradation is one, it is important that the relationship between fast charging and degradation, if any, should be understood.

 

A great and timely article. It's very useful to see the CCS charging specification chart.

Tesla's top charging rate is actually up to 135 kW today and they have hinted they may move to 150 kW in the not too distant future. They are experimenting with installing water-cooled cables on some stations which allows for thinner and more flexible cables that have less copper (or aluminum?) in the cable wiring.

The original CHAdeMO DC charging was limited to 500V at 125A for 60 kW but there are now a few stations capable of 500V at 200A for 100 kW. The Kia Soul EV is apparently capable of charging at an eventual peak rate of 68-70 kW on a 100 kW CHAdeMO charger. It will be interesting to see what GM announces for the Bolt DC charging specs in January at CES. My guess is they will support the 90 kW CCS spec mentioned in the article.

The real limiting factor for Bolt-sized battery is probably not the peak total combined kW rate but the amperage rate since initial charging on an empty battery is typically well below 400V. During the charge, the actual voltage being used will slowly rise as the battery fills up and the current will gradually go down if the battery needs to limit the incoming power. So, even the "90 kW" CCS might start out limited by the charger's amperage capability to 350V at 200A for 70 kW where a Tesla supercharger can support well past 300A and can immediately start charging a Model S 60 kWh battery at around 100 kW briefly and then at 85-90 kW for quite a while because the total charging rate is limited by the car and its battery's charging limits rather than being limited by the charger's 200A CCS limit.

I'm guessing the new CCS coalition aiming for 150 kW charging is just moving the spec to be 500V at 300A. While that's a benefit for a 90 kWh Audi car in a few years it could also be a benefit for a 55-60 kWh Chevy Bolt if it turns out to allow for faster initial charging by allowing a Bolt to start off charging at 350V at nearly 300A instead of 350V at 200A.

 

Jeff: Great article as always!
Most Ev batteries are 370V. I suspect that stays so because higher voltages results in more expensive isolation requirements and more expensive inverters.

To charge L3 DC at 240kW means a current of (240000/370=) ~650A . That is a lot of current requiring thick cables! For comparison: large homes are currently fused at 200A@220V. The battery can probably handle it, as the discharge current of a Tesla is even higher. Regenerative braking in the Volt charges the small Volt battery at up to 50kW, so a 7x larger Tesla battery should easily handle 7x as much power which is over 250kW.

I do wonder how the high currents affect the loss in the cables and batteries. Generally haste is always waste, and loss goes up worse-than-linear with current. Volt charge loses are about 18% toi ehat in the battery, cables and charger. Supercharging will make this likely worse, and that must affects the miles/kWh (MPGe) rating negatively.

At ~4% internal loss in the battery cells, a 240kW charge would generate 10kW waste heat. The battery chiller must work hard to haul that heat out so the temperature stays below 30C.

Personally, I don't think charge speed is the problem for daily commute use. Alternating work and sleep hours are enough to charge the battery at a leisurely L2 rate for a ~50miles daily commute. More battery capacity, longer lifetime and lower cost seem to be bigger issues than charge speed IMHO. Long distance travel with EVs will be a pain for much more time to come. That why the Volt is a good idea: large enough battery for daily commute, but a fallback for occasional long trips.

 

Loboc : One day the Betamax vs VHS vs DVD will work itself out. Oops. Streaming took over.

Each of those eras had a good 10-year run of basically unassailable dominance, though. And these are different CONNECTOR standards, which are basically additive. It's not like someone has to invent a different kind of wire to deliver a different kind of electricity to the site. 240 + neutral is normal. 120 is half of 240 + neutral. Three phase is just three sets of 240 + neutral hooked up differently, and commercial sites PROBABLY have that already brought to the distribution panel to support SOMETHING. Air condition, walk-in cooler, something... So what's left? Spending a couple hundred bucks on ESVE hardware and a couple more on skilled help wiring it up. It's not like you're gonna RIP OUT the J1772 connectors, even. They'll be there for all the then 8-year-old Volts...

 

Peter Coffin : Each of those eras had a good 10-year run of basically unassailable dominance, though. And these are different CONNECTOR standards, which are basically additive. It’s not like someone has to invent a different kind of wire to deliver a different kind of electricity to the site.240 + neutral is normal. 120 is half of 240 + neutral. Three phase is just three sets of 240 + neutral hooked up differently, and commercial sites PROBABLY have that already brought to the distribution panel to support SOMETHING. Air condition, walk-in cooler, something… So what’s left? Spending a couple hundred bucks on ESVE hardware and a couple more on skilled help wiring it up. It’s not like you’re gonna RIP OUT the J1772 connectors, even. They’ll be there for all the then 8-year-old Volts…
We do need a national standard. Even the primitive electrical wiring that Edison began to establish in the U.S. over 120 years ago has problems causing fires. So the NY fire depsrtment began taking control and putting up rules to prevent fires. From that we get the National Elcetric Code (NEC) and the NEMA (National Electric Manufacturing Association), so all electrical wiring (plugs, cables, outlets, junctions, lamps, appliances, fuses, and circuit breakers) will all work with each other and allow the public to enjoy electricity without getting shocked, burned, injured, or killed. The SAE standards does the same for automovite equipent, so the EVSE has to follow both NEMA and SAE standards.

I know that the DC charger must follow those J1772 standards now so the 2017 Chevy Bolt EV will be the first GM BEV to use it.

Raymond

 

I find the promise of SAE combo DCFC interesting not just for the power possibilities, but for the V2H (vehicle to home) possibilities too. DCFC EVSEs will always be more expensive than L2, but they can cover the entire range of 1KW to 100KW+ with one standard. A commercial public EVSE unit can provide high power opportunity charging (at high cost), while a home unit can provide L2 like power for a lower station cost, while also offering V2H functions. The standard provides for vehicle to EVSE negotiation, so the car can be in control of what it allows, feature and power wise.

 

This is just stupid as there is no reason they cannot make these fast chargers more compact. The fact that Tesla can easily pump 120Kw through something half the size of the current J1772 standard is just ridiculous. Now they want to make the port and the charging cord even larger just makes no sense and will not help the cause of the electric car.

Please someone in the standards community look at what Tesla has done with its charging cord and either copy it, license it or make something very similar as it is elegant and functional.

 

I wonder how many years it will take AUDI to build out a charging network that is similar to Tesla's? I wonder if the 2 companies will collaborate (allow each other's cars to use each other's charging stations).

Let's face facts, even Tesla's charging network is spotty. It covers less than 1/3 the entire interstate system making road trips across the country impractical for most owners. Now, if Tesla and Audi (or other companies) split the build-out cost, they might actually get a jump on the market.

 

"The Chevy Volt’s AC on-board charger is 3.3 kw level 2. The Chevy Spark EV’s level 2 charger is also 3.3 kw while the Nissan Leaf is 6.6 kw. Note that these vehicles are not pushing to the high end of level 2. The high end of AC Level 2 (19.2 kw) is usually for a pure battery electric vehicle like a Tesla."

Not sure what this is supposed to mean. Nissan Leaf and Chevy Spark are both "pure battery electric" vehicles, and both have available DC charging with rates much higher than 19.2 kW.

The 3.3 kW rate is sufficient to charge overnight on AC, so not really a problem, aside from being uneconomical at stations that charge by the hour.

 

My 2014 Spark EV usually recharge about 45-48kW (120A) up to 78% SOC, which is almost 2.2C for a 17.3kWh usable of 21.4kWh rated battery.

http://gm-volt.com/2013/08/02/spark-ev-versus-volt-battery/

So yes, please bring higher power DCFC to match future higher battery capacity.