Mini-QC Rapid-Charger (RC) Project for LEAF QC Port

[DaveEV]

We will be posting a demo of the 240VAC supply shortly (the one we just posted was a demo equivalent to 3-phase 380V supply).

Anyone else picturing something that has a J1772 receptacle on it than can do up to 80A on 208-240VAC for 20 kW charging on the road? And then plug into a NEMA 14-50 at home for 10 kW charging at home.

[philipscoggins]

How about a a J1772 for civilization and a NEMA 14-50 for campgrounds?

This could be a great advance in EV technology!

[hill]

We will be posting a demo of the 240VAC supply shortly (the one we just posted was a demo equivalent to 3-phase 380V supply).

Anyone else picturing something that has a J1772 receptacle on it than can do up to 80A on 208-240VAC for 20 kW charging on the road? And then plug into a NEMA 14-50 at home for 10 kW charging at home.

I'm curious about loss %. 240VAC to DC traction battery, versus 3-phase 380V (via a relatively efficient 240V to 380V - 3 phase rotary converter/motor) to traction battery loss.
.

[valerun]

We will be posting a demo of the 240VAC supply shortly (the one we just posted was a demo equivalent to 3-phase 380V supply).

Anyone else picturing something that has a J1772 receptacle on it than can do up to 80A on 208-240VAC for 20 kW charging on the road? And then plug into a NEMA 14-50 at home for 10 kW charging at home.

I'm curious about loss %. 240VAC to DC traction battery, versus 3-phase 380V (via a relatively efficient 240V to 380V - 3 phase rotary converter/motor) to traction battery loss.
.

Yes we were wondering about that, too. Unfortunately such a mechanical converter is quite heavy.

For our systems (assuming output is ~400VDC for a Leaf):
* A 208/240VAC system is ~95% efficient at 240VAC input / 22kW output, ~94% at 208V input / 18kW output
* A 380VAC system is ~96% efficient at 25kW output
* A 600VAC system is ~94% efficient at 18kW output

In all cases, the heat output is ~1kW - this is about as much as we can get out of that enclosure with air cooling before we hit thermal derating with 25C ambient (derating happens starting at 55C
heatsink temp).

J1772 input is possible. It's a good idea for us to demo sometime soon - thanks for suggestion. The chargers already support J1772 protocol natively so this should be relatively seamless.

V

[NYLEAF]

Would this theoretically allow a Tesla without the second on-board charger to achieve 20kW charging from an 80amp J1772 charger by using this device combined with a CHAdeMO to Tesla adapter? Probably not at all cost effective, but a cool thought nonetheless.

[valerun]

Would this theoretically allow a Tesla without the second on-board charger to achieve 20kW charging from an 80amp J1772 charger by using this device combined with a CHAdeMO to Tesla adapter? Probably not at all cost effective, but a cool thought nonetheless.

theoretically - yes. Practically, I would just add a second charger (I think it's a Tesla-supported upgrade for $4-5k, right?)

[TonyWilliams]

Would this theoretically allow a Tesla without the second on-board charger to achieve 20kW charging from an 80amp J1772 charger by using this device combined with a CHAdeMO to Tesla adapter? Probably not at all cost effective, but a cool thought nonetheless.

theoretically - yes. Practically, I would just add a second charger (I think it's a Tesla-supported upgrade for $4-5k, right?)

$3500 installed.

http://shop.teslamotors.com/products/2n ... rd-charger" onclick="window.open(this.href);return false;

[Heinz]

First of all, a big thank you to everyone who has contributed to this project. It's a remarkable piece of engineering, electrically and mechanically.

Even though I'm not an expert in high power electronics I have a background in tube guitar amp building. So I had a look at the EMW charger schematics. The power stage uses some serial/stacked capacitors in order to increase the maximum voltage. This is common practice in tube amps, as well. However, it seems advisable to add balancing resistors so the two caps share the voltage equally. Without balancing resistors the center voltage is not guaranteed to be at half the total voltage and may drift due to age, temperature and tolerances. Eventually, one of the caps may experience a voltage in excess of its rating which will destroy it. Two 100k 1/2W resistors in parallel to the caps should do the trick.

The discussion about the QC connector pins and materials also caught my attention. I did some research on IEC 60309 plugs which are rated up to 125A. These are somewhat similar in construction and contact design. The pin material on these industry standard plugs is brass up to 32A and nickel (or nickel coated brass) for 63A and 125A. However, I was unable to find out the exact plug and pin diameters. I have some 16A plugs at home and the pin diameters are 5mm for the phases and 7mm for the neutral. Since there are so many different types of these plugs I'm wondering if there is one that has 9mm pins. These may be a good starting point for a DIY chademo connector. I will go to a hardware store and take measurements.

[valerun]

First of all, a big thank you to everyone who has contributed to this project. It's a remarkable piece of engineering, electrically and mechanically.

Even though I'm not an expert in high power electronics I have a background in tube guitar amp building. So I had a look at the EMW charger schematics. The power stage uses some serial/stacked capacitors in order to increase the maximum voltage. This is common practice in tube amps, as well. However, it seems advisable to add balancing resistors so the two caps share the voltage equally. Without balancing resistors the center voltage is not guaranteed to be at half the total voltage and may drift due to age, temperature and tolerances. Eventually, one of the caps may experience a voltage in excess of its rating which will destroy it. Two 100k 1/2W resistors in parallel to the caps should do the trick.

The discussion about the QC connector pins and materials also caught my attention. I did some research on IEC 60309 plugs which are rated up to 125A. These are somewhat similar in construction and contact design. The pin material on these industry standard plugs is brass up to 32A and nickel (or nickel coated brass) for 63A and 125A. However, I was unable to find out the exact plug and pin diameters. I have some 16A plugs at home and the pin diameters are 5mm for the phases and 7mm for the neutral. Since there are so many different types of these plugs I'm wondering if there is one that has 9mm pins. These may be a good starting point for a DIY chademo connector. I will go to a hardware store and take measurements.

Thanks Heinz for your kind words and for your suggestions. You are absolutely correct regarding balancing resistors. This will have to be done in the next revision of the boards.

Regarding pins - after a reasonably long search, we now can finally make complete plugs with pins and all. We have found a local 3D print shop that is not charging an arm and a leg for large prints and who was willing to work with us through 3+ iterations of the build parameters to avoid warping, account for shrinkage, etc, etc. We have also found a precision machine shop that could build the pins to our exact specs. Finally, we found a precision plating shop that could nickel & silver-plate our pins to the same spec as Nissan parts (yes, we measured the silver thickness with precision instruments). large 9mm pins are pure 110 copper with 1 mil silver plate, small signal pins are brass with 0.5 mil nickel plate.

Pins pic attached. You can now buy the plugs from our store with just 2-week lead time.

Val

[TonyWilliams]

Val, great work on the pins. We've been going through much the same motions with our own pin production issues, so I am intimately familiar with how much leg work is required.