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Ingineer
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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 11:42 am

GeekEV wrote:That sounds great, Phil! Though I'm a bit confused by the statement that the LEAF draws 16a. It's a 3.3Kw changer in the car, right? By my math, that's 13.75A max at 240v. What am I missing?

But in any case, this rev 2 mod will be capable of up to 20A (if the car supports it)? Did I read that right?

Thanks!
No, Nissan tells us the charger output is 3.3kW. Assuming a 240v circuit, The input is 16a x 240v or 3.84kva. kva is equal to kW only when there is unity power factor (1). Since the LEAF's on-board charger is power-factor corrected, it's probably close enough to call it unity for rough calculations.

The LEAF's on-board charger is a power conversion device, and in accordance with physics and the laws of thermodynamics, it is nowhere near 100% efficient.

As for the 20A capability, I will not know if I can allow it yet, as I mentioned more testing is required. But the prototype allows it.

-Phil
Last edited by Ingineer on Thu May 19, 2011 11:46 am, edited 1 time in total.
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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 11:45 am

Ingineer wrote:Nissan tells us the charger output is 3.3kW. Assuming a 240v circuit, The input is 16a x 240v or 3.84kva. kva is equal to kW only when there is unity power factor (1). Since the LEAF's on-board charger is power-factor corrected, it's probably close enough to call it unity for rough calculations.
Got it. I thought, mistakenly, it was a 3.3kW draw, not output... That makes sense.

Just for academic purposes, based on what you said about the 33.3% duty cycle and 20a, that WOULD apply if using it with something other than a LEAF that supported higher current?

Thanks!

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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 11:48 am

GeekEV wrote:Got it. I thought, mistakenly, it was a 3.3kW draw, not output... That makes sense.

Just for academic purposes, based on what you said about the 33.3% duty cycle and 20a, that WOULD apply if using it with something other than a LEAF that supported higher current?

Thanks!
Correct. There is no EV currently on the market right now I'm aware of, except for a Tesla with a converter dongle, that can draw more then 16A from J1772.

-Phil
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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 12:02 pm

QueenBee wrote:I understand KISS well but I think anyone who plans on using this along with a quick220 would certainly need the 12A/220 model or as Phil noted at 16A draw a 15amp breaker will trip so if you didn't have two 20amp circuits you would be stuck at 12 amp 110volt draw.
I'd have to agree with this statement. Of the few garages I have scouted for use of the Quick 220 none of them had two dedicated 20 amp outlets. At best I encountered one 20 amp and one 15 amp outlet. So in this scenario the Rev 2 would be popping breakers all the time.

While I want the full 16 amps to use at RV parks and with dryer plugs, I'd hate to vibe up the flexibility the Quick220 offers.

I vote for user selectable amperage settings. Then it becomes a full featured, "give me all you've got" EVSE!

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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 12:07 pm

nader wrote:Of the few garages I have scouted for use of the Quick 220 none of them had two dedicated 20 amp outlets. At best I encountered one 20 amp and one 15 amp outlet. So in this scenario the Rev 2 would be popping breakers all the time.

While I want the full 16 amps to use at RV parks and with dryer plugs, I'd hate to vibe up the flexibility the Quick220 offers.

I vote for user selectable amperage settings. Then it becomes a full featured, "give me all you've got" EVSE!
The question is, If I have to spend more dev time adding the user interface (as simple as it may be), how much extra are you willing to pay for selectable amperages?

-Phil
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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 12:46 pm

Ingineer wrote:
IBELEAF wrote:I am probably way ahead of time, but still curious if this upgrade will work with future Leafs that might have 6.6 kWh chargers
In the prototype, I have set the Pilot to 33.3% duty cycle, which will allow up to 20a. So if you had an EV with a 6.6kva charger, you would only get 4.8kva. That's about ~73%, so not bad.

I can't safely increase beyond 20a without new hardware in the EVSE. And as it is, I need to run extensive tests at 20a to verify there is no problem.

6.6kva will require 27.5a, which really should have better than 12awg cable as well, so really the whole EVSE would need to be replaced. (Except for the sticker on the front that says "Zero Emission"! =)
So the Pilot is set to 33.3% duty cycle in all cases? So that's telling the vehicle that 20A is available at 120V and 240V?
On the LEAF, you point out the car will limit to 12A even if offered more by the EVSE, so it's a non issue for the current LEAF. Future LEAFs or other EVs might take the full 20A at 120V being offered by the EVSE, tripping 15A circuits.

I'm thinking that using a Quick220 or similar, that you will on occasion, be plugging in to 15A circuits and 16A would trip the breaker.

I also think about situations where the circuit is shared with a coke machine or some other modest loads or maybe other hotel rooms if you decide to Quick220 (with permission of course!) at a bed and breakfast etc.

So ultimately, you have three settings (based on the LEAF EVSE)

Auto (Always offers 20A, cars that accept more than 12A at 120V can be problemeatic)
8A (shared circuit 120V or 240V)
12A (dedicated 15A circuit 120V or 240V)
16A (dedicated 20A circuit 120V or 240V)
20A (dedicated 30A circuit 240V)

Or the Auto mode could be more sophisticated: (12A at 120V, 20A at 240V).

Value of selectable current option: +$200 as an easy figure. I'd pay more though, but given LEAF owner market and the effort, that seems a good price point. $100 would include more people, though the value is to people who need that sophistication. User selectable current is too complicated a feature for people who are blissfully ignorant of Amps and circuit breakers and want to sty that way.

To speed development, for the moment, you could offer the full level 2 mod for the LEAF, and people who need lower current (12A) or need both low (12A) and high current (16A) at 240V could just get two mod units and use the unit that suits the need. So they have to purchase two units, but they have hte flexibility of current level by using one or the other of the two units they've purchased. Long term a fancy, user adjustable current draw with an Auto mode for default would address more situations, but that can come later, maybe after the Phil Inc. public offering!

Purchasing two units is an additional cost outlay, but is partially offset by the additional cost a selectable current model would add, the development time, including finding a reliable moisture proof switch mechanism, units available sooner, redundancy of having two units for convenience adn backup etc.

You can put a catchy label on them: "Phil's 12A go anywhere EVSE", "Phil's 16A enhanced EVSE dongle". Ok, I leave that one to your marketing department! A large easy to read 12A or 16A on the units would make them easy to identify annd simple to use.
Last edited by ElectricVehicle on Thu May 19, 2011 12:47 pm, edited 1 time in total.
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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 12:46 pm

Ingineer wrote: I'd love to hear what everyone thinks.

-Phil
I'm thinking I wish I learned about this yesterday when my EVSE was still in your hands! ;) I'm not sure I'll want to bother with sending it back, but maybe...

Thanks for pushing the design along!

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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 12:53 pm

Ingineer wrote:6.6kva will require 27.5a, which really should have better than 12awg cable as well, so really the whole EVSE would need to be replaced. (Except for the sticker on the front that says "Zero Emission"! =)
The 6.6 kW chargers may be rated for charging power, so the input power would be higher. I consider the Level 2 to be a 30 or 32A supply at 240V, in any case, as you point out, it would require replacing most of the Nissan EVSE components for currents over 20A.

In the initial [J1772] standard, two charging levels are defined.

Code: Select all

Level        Voltage  Peak current 
AC Level 1   120 V    16 A 
AC Level 2   240 V    32 A (2001) 80 A (2009)
http://en.wikipedia.org/wiki/SAE_J1772
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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 12:57 pm

To save on development costs, I think it would be best to keep it simple. If someone want's 12A then purchase the upgrade Rev1. If someone want's to charge at higher current then purchase Rev2.
In the prototype, I have set the Pilot to 33.3% duty cycle, which will allow up to 20a. So if you had an EV with a 6.6kva charger, you would only get 4.8kva. That's about ~73%, so not bad.
Wouldn't it be safer to set the pilot to allow up to 16A Max. Currently the Leaf can only draw 16A but when the next generation of Leaf comes with the 6.6kWh charger, trying to pull 20A from a 20A plug is bound to cause a few tripped breakers.
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Re: Revision 2 upgrade for Nissan EVSE - Allows full level 2

Thu May 19, 2011 1:20 pm

For those talking about using this with a Quick220 type device, I have a question. This is probably my electrical naïveté taking here, but wouldn't the 20A (maximum) draw be effectively split between the two 120v legs such that each circuit would effectively see 10A? That would be fine on a standard 15A circuit, no?

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