Level 3 (public quick charge stations)

KeiJidosha said:

Mobile L3 is cool and all. But EV charge capable emergency AAA trucks, roaming the freeway, are not a substitute for permanent QC installed in useful locations. The current lack of public charging infrastructure teaches new EV owners that the LEAF is less useful than it could be.

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I agree that until a network of QC is widely available, consumers will be more hesitant to purchase an EV. Our mobile solution is not designed to be a replacement for public chargers but rather a complement as Level 3 charging will not be widely available for some time.

Vincent said:

KeiJidosha said:

Mobile L3 is cool and all. But EV charge capable emergency AAA trucks, roaming the freeway, are not a substitute for permanent QC installed in useful locations. The current lack of public charging infrastructure teaches new EV owners that the LEAF is less useful than it could be.

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I agree that until a network of QC is widely available, consumers will be more hesitant to purchase an EV. Our mobile solution is not designed to be a replacement for public chargers but rather a complement as Level 3 charging will not be widely available for some time.

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Makes sense. Wish you were on the West Coast. Your rig would be a hit at our LEAF get-togethers. It would allow members with range or schedule issues to attend.

If these are deployed before public L3 stations, I see a rash of AAA calls in our future.

"Hi AAA, my car is nearly dead and needs a QC boost. I'm at the HomeTown Buffet in Mira Mesa. See you soon."

drees said:

Vincent said:

The generator that powers the Level 3 charger is 95% efficient. It is fully integrated into the truck and uses the truck's engine to act as the power source for the Level 3 charger. The generator is a 60kW 3-phase unit. Note that the vehicle used to test the mobile application of the DC charger was the Mitsubishi iMiev. Providing a full Level 3 charge (85% of full battery capacity) on the iMiev required 20 minutes and used one gallon of diesel.I know that the battery pack on the Leaf has a different capacity.

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There is no way you are converting 95% of the energy of a gallon of diesel into electricity (~38 kWh -> ~36 kWh.) for one reason alone - the truck's engine from which your generator draw's it's kinetic energy to convert to electricity is no more than 45% efficient at it's optimal loading point and most likely less than that since it's not optimized for power generation.

But for the sake of the argument let's assume it's 45% efficient so it's able to convert a gallon of diesel (38 kWh equivalent) into 17 kWh equivalent of kinetic energy. Then your generator which is 95% efficient is able to covert the 17 kWh into 16 kWh of electricity. (This still ignores any conversion losses of the DC quick charger itself which must convert the 3-phase AC to DC for the car - this should be 5% or less, though)

Still quite a bit short of a full charge for the Leaf, but enough to drive it about 50 miles or so - basically equivalent to the appx 50 mpg a TDI gets on the highway. Can't complain about that if you are stranded and need a mobile quick charge to get you to the nearest fixed charging point, though.

It would be interesting to see the official specs, though.

Vincent said:

*In the interest of full-disclosure, I work for Real Power, the company that created the Mobile DC Charging prototype vehicle.

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Funny - your original post indicated that you were a third party. Might want to update that.

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Note that this data was obtained while charging a Mitsubishi iMiev and, as I have mentioned earlier, we have not had a chance to charge a Leaf as of yet. The charging vehicle is equipped with a 6.6L Duramax Turbodiesel engine. The generator is a 60kW 3-phase unit and the EV Charging unit is an Eaton model with a 50kW capacity.

1 gallon of diesel = 130,500 BTU = 38.2 kWh

i-MiEV has a 16kW battery pack typical charge is around 12.8kWh (80% charge)

Assume the duramax is 40% efficient, our generator is 90% efficient and the charger is 95% efficient.

38.2 kWh * .4 = 15.28 kWh * .9 = 13.75kWh * .95 = 13.1 kWh or approximately 12.8 kWh


So that is why (and how) we only use 1 gallon of diesel to provide a full Level 3 charge on a Mitsubishi iMiev. It'll be really interesting to see how we perform when charging a Nissan Leaf.

Comments are always welcome!

90% efficiency out of the generator is pretty good.. that and the Eaton L3 charger are the pricey units, probably a lot more than the truck itself

The problem is the lack of cars with L3 charging receptacles.

Herm said:

90% efficiency out of the generator is pretty good.. that and the Eaton L3 charger are the pricey units, probably a lot more than the truck itself

The problem is the lack of cars with L3 charging receptacles.

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Agreed.

The Leaf, iMiev (or i) and soon the Think are the only vehicles currently available with a Level 3 receptacle. However, the mobile/rescue charging vehicle also has a Level 2 on board for a "top up" in case of emergency. So it can support all other EV, with the proper charging adapter for the 240-plug.

Also, the generator is actually the least expensive piece of the puzzle. The L3 charger is the most, and the production truck will fall somewhere in between...

Hopefully more cars will come out with the chademo L3 charging receptacle, I would think its a way to future proof the car and is not expensive to implement.. basically the connector itself, a relay and some extra wiring.

The L3 chargers are overpriced now due to the uniqueness of their application, but that will come down. They are essentially 50kw variable DC power supplies, outputting 500V DC.

Your trucks could also act like portable generators in emergencies, if fitted with the proper inverter.. that may be an additional revenue stream if you are under contract to the fed, state and local governments.

Herm said:

Hopefully more cars will come out with the chademo L3 charging receptacle, I would think its a way to future proof the car and is not expensive to implement.. basically the connector itself, a relay and some extra wiring.

The L3 chargers are overpriced now due to the uniqueness of their application, but that will come down. They are essentially 50kw variable DC power supplies, outputting 500V DC.

Your trucks could also act like portable generators in emergencies, if fitted with the proper inverter.. that may be an additional revenue stream if you are under contract to the fed, state and local governments.

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Herm,

There's no need for an inverter as our systems produce pure AC from the get-go. Pure sine wave @ 60hz. That is our core business. We already count local, state and Federal government as our clients. Our generator outputs range from 12kW to 150kW, all driven from the truck's engine using a pto gear.

Vincent said:

There's no need for an inverter as our systems produce pure AC from the get-go.

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But ... but ... L3 is DC, not AC.

planet4ever said:

Vincent said:

There's no need for an inverter as our systems produce pure AC from the get-go.

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But ... but ... L3 is DC, not AC.

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Yep. A truly integrated mobile quick charge station would integrate that huge L3 DC quick charge station into the area under the flatbed and get rid of the AC/DC conversion which saps an extra 5-10% efficiency out of the system.

drees said:

planet4ever said:

Vincent said:

There's no need for an inverter as our systems produce pure AC from the get-go.

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But ... but ... L3 is DC, not AC.

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Yep. A truly integrated mobile quick charge station would integrate that huge L3 DC quick charge station into the area under the flatbed and get rid of the AC/DC conversion which saps an extra 5-10% efficiency out of the system.

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Yeah, but, they don't need an inverter because they start with AC (must be an alternator, not a generator)...so they need a rectifier instead!

I don't think that would buy you anything since the charger still needs to control the charging current and that is actually easier to do on the AC side of the equation.

>>> A truly integrated mobile quick charge station would integrate that huge L3 DC quick charge station into the area under the flatbed and get rid of the AC/DC conversion which saps an extra 5-10% efficiency out of the system.

Vincent said:

i-MiEV has a 16kW battery pack typical charge is around 12.8kWh (80% charge)

Assume the duramax is 40% efficient, our generator is 90% efficient and the charger is 95% efficient.

38.2 kWh * .4 = 15.28 kWh * .9 = 13.75kWh * .95 = 13.1 kWh or approximately 12.8 kWh

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Interesting. So, you think charging is 95% efficient ? This would include ac-dc conversion at the charger + battery charging losses ...

mine isnt. it would appear to be the low to mid 80's for me at 120 volts. quick charges tend to generate more heat.

DaveinOlyWA said:

mine isnt. it would appear to be the low to mid 80's for me at 120 volts

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How can you tell ?

evnow said:

DaveinOlyWA said:

mine isnt. it would appear to be the low to mid 80's for me at 120 volts

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How can you tell ?

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that is a good question and that is why i dont have a specific #. but what i do have is an exact figure for what i have taken out of the wall.

and i have what the car says i have averaged as far as miles per KWH. the lifetime figure from the car is 4.1 and its not resettable. at least i have not figured out that.

then i take carwings data (with a grain of salt) and provide guess work. my efficiency could easily be as low as 75%

lonndoggie said:

drees said:

Vincent said:

There's no need for an inverter as our systems produce pure AC from the get-go.

Click to expand...

But ... but ... L3 is DC, not AC.

Click to expand...

Yep. A truly integrated mobile quick charge station would integrate that huge L3 DC quick charge station into the area under the flatbed and get rid of the AC/DC conversion which saps an extra 5-10% efficiency out of the system.

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Yeah, but, they don't need an inverter because they start with AC (must be an alternator, not a generator)...so they need a rectifier instead![/quote]

The generator used for this application generates 60kW of 3-phase AC power at 60hz. We do not require an inverter on our system as the L3 charger has an inverter integrated into it. The L3 is a commercial grade system designed for permanent mounting to be tied to the grid (AC) at a gas station or shopping mall.

Regarding the comment about "truly integrated mobile quick charge station", the truck you saw in the pictures and video is a "proof of concept" vehicle which was assembled just to prove that we could do it. We used an existing, off the shelf L3 charger and mounted it to a truck equipped with our generator system. It was never designed or built to be sold with the equipment configured in such a way.

Now that we know that the system works, we are designing a production unit of an EV Rescue/Recovery truck which will be commercially available. The design of the production unit includes reconfiguration of the L3 unit for mobile application so that it fits in a much smaller space (think of a highway box or a service body truck). We're hoping to have a true production unit ready by June.

Thanks for the great feedback. Keep it coming!

Vincent

DaveinOlyWA said:

the lifetime figure from the car is 4.1 and its not resettable. at least i have not figured out that.

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The average energy economy on the dash can be reset, if you want to do so, by holding down the upper right button of the square array of 4 buttons to the left of the steering column (similar to reseting the trip odometers by holding down the lower left button) - see page 2-27 of the main manual.

On the center console "energy" screens, you can save and reset that version of energy economy - the current average adds a new column to the history histogram and it starts over. To do that, use the "reset" button on the Energy Economy screen (Nav manual pages 2-7,2-8). Then when you drill down to History, you'll see an additional column.

I agree that if the car's own average economy figure has any validity at all (the 4.1 figure in your example above, which is pretty much what we are getting), the recharge efficiency (all aspects from wall to when the car starts measuring it) is on the order of 75-80%.

wsbca said:

DaveinOlyWA said:

the lifetime figure from the car is 4.1 and its not resettable. at least i have not figured out that.

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The average energy economy on the dash can be reset, if you want to do so, by holding down the upper right button of the square array of 4 buttons to the left of the steering column (similar to reseting the trip odometers by holding down the lower left button) - see page 2-27 of the main manual.

On the center console "energy" screens, you can save and reset that version of energy economy - the current average adds a new column to the history histogram and it starts over. To do that, use the "reset" button on the Energy Economy screen (Nav manual pages 2-7,2-8). Then when you drill down to History, you'll see an additional column.

I agree that if the car's own average economy figure has any validity at all (the 4.1 figure in your example above, which is pretty much what we are getting), the recharge overhead (all aspects from wall to when the car starts measuring it) is on the order of 75-80%.

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thanks for info on LT reset... i never read manual. maybe i should.

as far as the trip meter on energy screen, i reset set that daily and use it for a guideline of energy efficiency as well and that is giving me around 70-75% but that is penalized on climate controls which has to be factored out of the equation thus the carwings data on accessories reference

L3 charger at West Way Nissan, Oxford, UK: