Portable 120/240 Autodetecting Charger $700

[jwallace3]

Hello peeps. It's been quite a while since I've been on here. I have recieved many emails about the mod I was working on and unfortunately that project got shelved over developing a complete new charger. I've been working with my senior engineering students at Western Kentucky Univerisity on developing a 120/240 combination portable charger and I'm glad to say that it's finished! We are looking to make some enhancements before the production model is ready, but I just thought I'd get some feedback on the pricetag of around $700. The profit margin isn't huge at that number, but we are hoping to get the cost down with volume purchasing of parts such as the J1772 connector. We are looking into UL listing as well. Probably be a while before that happens. Here is a quick rundown of the specs:

120/240 auto detecting
12 amps AC @120
16 amps AC @240 (could be more, but the leaf doesn't need it)
GFCI
Nema L15-30 twistlock connector for switching out of pigtails
J1772 connector with 10Ga wire (a little heavier than we wanted, but was the least expensive/may end up with something smaller for better portablility)
3 LEDs representing AC present, Charging, and Fault condition

Future enhancements:
Metering capability
LCD screen
Bluetooth for connection to smartphones
Any other ideas people are willing to pitch

Look forward to any feedback you all have to offer. I will post a pic/video of the prototype working soon.

 

[smkettner]

16 amps AC @240 (could be more, but the leaf doesn't need it)

2013 Leaf could use more. Adjustable max current would also enable install on smaller existing circuits such 24a on a 30a dryer circuit.
With just 16a you will practically be obsolete by the time you have it on the market.

 

[garygid]

Settable Max-Amps.
Waterproof?
What J1772 connector?
Fused?
Weight and size?
Cord length?
Diode check?
Fully J1772 spec operation?
Rugged box?
Would UL "list" it?
Handle power outage and brown-outs?
GFI automatic reset?

 

[jwallace3]

16 amps AC @240 (could be more, but the leaf doesn't need it)

2013 Leaf could use more. Adjustable max current would also enable install on smaller existing circuits such 24a on a 30a dryer circuit.
With just 16a you will practically be obsolete by the time you have it on the market.

We have looked into that and will probably incorporate adjustable current for 240 charging. We looked into a 16/24 amp capability with just a simple push of a button. The current model doesn't have that, but it's not a ton of work to incorporate it. That would accomodate up to roughly a 6kW charger. Thanks for the input!

We are looking to make limited quantities for cost at the current moment as well once we get a more permanent enclosure picked out as well.

 

[mitch672]

jwallace3, you might want to checkout the "OpenEVSE" threads and google project, that's all been done, and there is an RGB LCD display now integrated, most use a 30A relay so it's capable up to 24A of current, which is enough for most (for now).

http://code.google.com/p/open-evse/" onclick="window.open(this.href);return false;

 

[TonyWilliams]

It needs to go to 30 or 32 amps. Ford Focus will use that today. LEAF will in a few more months.

 

[jwallace3]

Settable Max-Amps.
Waterproof? Yes
What J1772 connector? http://avnetexpress.avnet.com/store/em/EMController/Connector-Other/ITT-Interconnect-Solutions/EVC-C-30A-600S-20/_/R-13470751/A-13470751/An-0?action=part&catalogId=500201&langId=-1&storeId=500201&listIndex=-1" onclick="window.open(this.href);return false;
Fused? Yes
Weight and size? Right now the box is roughly 2 inches wider than the Nissan L1 ESVE. But this will be smaller soon. Dont' have an official weight, but I'll get you one of the current build.
Cord length? Roughly 20' without an adapting pigtail attached.
Diode check? No.
Fully J1772 spec operation? It depends of how you define full. If you define it as all of the possible conditions are addressed, yes, then we are fully J1772 operational. We address each condition, but certain ones that shouldn't be an error state (such as battery ventilation required) would send our charger into an error state.
Rugged box? Yes
Would UL "list" it? We are working on that. There is a business case we are currently working on and some Seed/grant money that we may be able to use for startup.
Handle power outage and brown-outs? Power outage - Yes, Brown outs - Will be once we finish the metering functionality. We will shut down when the charger sees less than 90 volts on either phase. That is per ANSI.
GFI automatic reset? You would have to unplug it from the source to reset the GFI or any other fault condition. This may be resettable via bluetooth on your phone in the future. We have to talk internally about safety issues and if it would jeapardize safety in any way first.

 

[jwallace3]

It needs to go to 30 or 32 amps. Ford Focus will use that today. LEAF will in a few more months.

Well yes, but you're kind of limited on the portability of it then. You would need a 40 amp outlet, bigger cable, etc. The vehicle won't pull more that you tell it to. The idea is really to give you more than just 120 opportunity charging.

 

[jwallace3]

jwallace3, you might want to checkout the "OpenEVSE" threads and google project, that's all been done, and there is an RGB LCD display now integrated, most use a 30A relay so it's capable up to 24A of current, which is enough for most (for now).

http://code.google.com/p/open-evse/" onclick="window.open(this.href);return false;

That's cool. I'm sure it's been done several times. I started this project back in the Fall with the engineering department just because I thought it would be a neat Senior project for the students. Turned out it was a pretty cool project and the students did great. The university has all the equipment to make and test a professional grade product. We are putting this thing through vibration, shock, water proof testing, etc. The whole 9 yards to make sure it's tough and reliable. The LCD part is basically done, we just have to finish our custom graphics and such.

The open source stuff is cool and I often contribute to those discussions. Thanks for the input.

 

[TonyWilliams]

It needs to go to 30 or 32 amps. Ford Focus will use that today. LEAF will in a few more months.

Well yes, but you're kind of limited on the portability of it then. You would need a 40 amp outlet, bigger cable, etc. The vehicle won't pull more that you tell it to. The idea is really to give you more than just 120 opportunity charging.

I wouldn't be limited if I could select the amps.

The limit is just "suffer the reduced charge with our product".

 

[garygid]

Without the diode check, it is not really J1772 compliant, right?
I think the diode (safely related) test is not optional in the specs.

 

[jwallace3]

Without the diode check, it is not really J1772 compliant, right?
I think the diode (safely related) test is not optional in the specs.

It's not required. Nissan nor the Blink chargers have it either. There are other ways to address the safety issues. It seems most manufacturers are using timers and other creative ways to make sure the end isn't sitting in a pool of muddy water.

 

[jwallace3]

It needs to go to 30 or 32 amps. Ford Focus will use that today. LEAF will in a few more months.

Well yes, but you're kind of limited on the portability of it then. You would need a 40 amp outlet, bigger cable, etc. The vehicle won't pull more that you tell it to. The idea is really to give you more than just 120 opportunity charging.

I wouldn't be limited if I could select the amps.

The limit is just "suffer the reduced charge with our product".

You could select with this, but you can ask for more that the circuit and cabling is rated for. That's the danger of giving that ability to the consumer. Our cabling and connectors are rated at 30 amps. Currently our traces on our PCB are only desined to carry 18, but that's already been addressed in the newer design. @24 amps that's 5.76kW That would charge a completely dead LEAF or Focus in the 4-5 hour range. We may be able to go to around 26 amps as well to get over the 6kW threshold.

 

[DarkStar]

Without the diode check, it is not really J1772 compliant, right?
I think the diode (safely related) test is not optional in the specs.

It's not required. Nissan nor the Blink chargers have it either. There are other ways to address the safety issues. It seems most manufacturers are using timers and other creative ways to make sure the end isn't sitting in a pool of muddy water.

I've confirmed that the Blink EVSE units definitely perform a diode check prior to charging a vehicle. We've even had a local Leaf owner get their charger replace due to the diode going bad. That took a lot of convincing due to the AV units or the Nissan L1 units doing a diode check. I ended up driving over to their house and verifying the Blink was functional on my Leaf.

I can also confirm that the Shorepower EVSE units perform a diode check also and I'm fairly certain that the Coulomb units do as well.

On anything 240 volts, I would highly recommend that the diode check be performed. This prevents a random puddle of water from activating the circuit.

 

[chris1howell]

Suggested Safety features...

Diode check (a timer on a car can't help an EVSE with this one)
State D Ventilation required
Ground check and monitoring during charging
Stuck relay detection
GFCI auto reset
GFCI auto testing

 

[jwallace3]

You've got me curious now. We have a car simulator at the lab I should grab to see if my blink does the diode test. I thought I had checked it before and it worked with a simple resistor. Anyhow, the diode check is really for permanently installed units. In case someone left the plug laying on the ground after charging and it rained, etc. It's not a huge task to check for a diode, however, the way in which the standard suggests to doing it is rather costly and more difficult to implement. We have some lawyers who are looking at this stuff now to see what we need to do to be on the straight so I'm sure we will get some suggestions. With a portable unit you won't be leaving it permanently installed anywhere, otherwise it would probably be gone after a while. Our unit, if left not connected to a vehicle for more than a few minutes will shut off and have to be reset to prevent any accidental operation. We also require that the wall be plugged in first and a few seconds before the J1772 connector can be plugged in so that it can check for any paths between any of the AC and ground pins. This pretty much makes sure that a dangerous situation can't occur. If we make a mountable unit we will implement the diode check, but for this version we probably won't. In the event we did on the portable unit, it would be our own way to check it, not the way the standard suggests to with the -12 volt portion of the squarewave.

Without the diode check, it is not really J1772 compliant, right?
I think the diode (safely related) test is not optional in the specs.

It's not required. Nissan nor the Blink chargers have it either. There are other ways to address the safety issues. It seems most manufacturers are using timers and other creative ways to make sure the end isn't sitting in a pool of muddy water.

I've confirmed that the Blink EVSE units definitely perform a diode check prior to charging a vehicle. We've even had a local Leaf owner get their charger replace due to the diode going bad. That took a lot of convincing due to the AV units or the Nissan L1 units doing a diode check. I ended up driving over to their house and verifying the Blink was functional on my Leaf.

I can also confirm that the Shorepower EVSE units perform a diode check also and I'm fairly certain that the Coulomb units do as well.

On anything 240 volts, I would highly recommend that the diode check be performed. This prevents a random puddle of water from activating the circuit.

 

[jwallace3]

Suggested Safety features...

Diode check (a timer on a car can't help an EVSE with this one)
State D Ventilation required
Ground check and monitoring during charging
Stuck relay detection
GFCI auto reset
GFCI auto testing

We are not building this unit for cars that would use state D so we just error out in this area.
We do constantly monitor the ground path while charging. This is also how we detect whether it's 120 or 240.
We do a stuck relay check at startup.
We check the GFCI at startup as well just as any newer GFCI device does.
GFCI autoreset.....I think that for a portable unit, if the GFCI detects an alternate current path that a human should have to intervien and remidy the situation before the GFCI can reset and power be re-applied to the cable.

Thanks for the suggestions Chris! How did your charger project end up? We chatted a lot during the early stages of your project about 6-8 months ago.

 

[chris1howell]

It's going very well, my project has been open sourced as "OpenEVSE".

OpenEVSE is mature and fully supports the J1772 spec. It is currently in use by drivers of the LEAF, VOLT, i-MiEV and PiP.

OpenEVSE implements the pilot with diode check with a 1w DC-DC converter (MicropowerDirect D107E), 5V in and +12 and -12 out. A LF353 opamp is powered by -12/+12 and is controlled by the microprocessor. The Microprocesser reads the pilot to perform the diode check and read the state.

Source code and Schematics are at the OpenEVSE site... http://code.google.com/p/open-evse/

 

[garygid]

"... Currently our traces on our PCB are only desined to carry 18 ..."

If any traces carry any of the high current,
there is something wrong with your design.
(In my professional opinion.)

240v at 24 amps is not 6.6 kW charging,
or even 6.6 kW into the charger.

Will your EVSE "smoke" if the input is single-phase 240v?
Does it require 240v split phase (two 120v-to-Ground feeds)?

Just because others have ignored the diode check does
not mean that it is not "required" in the J1772 spec.

But, maybe you have the same liability insurance that Nissan has?

 

[jwallace3]

"... Currently our traces on our PCB are only desined to carry 18 ..."

If any traces carry any of the high current,
there is something wrong with your design.
(In my professional opinion.)

240v at 24 amps is not 6.6 kW charging,
or even 6.6 kW into the charger.

Will your EVSE "smoke" if the input is single-phase 240v?
Does it require 240v split phase (two 120v-to-Ground feeds)?

Just because others have ignored the diode check does
not mean that it is not "required" in the J1772 spec.

But, maybe you have the same liability insurance that Nissan has?

The students did use traces in the prototype design, which I don't agree with either, but then again they were learning. We have that changed with our newer design to accommodate metering CTs.

As far as single phase 240 as of right now there are 2 parts that monitor the AC lines paths to ground that we have to talk to the manufacturer to get an answer. The spec sheet doesn't have a max voltage rating which is odd. Other than that the ESVE can use single phase 240 (240 line to ground).

As far as current draw, if voltage was ideal you're looking at 27.5 amps to get 6.6kW. The maximum current rating for the Nema twist lock connectors is 30 amps. You have to build a little contingency in there for low line voltage so that you don't trip the breaker if you power provider is doing conservation voltage reduction. Plus if a breaker is old it may trip at 28 amps and not 30. 26 amps gets you pretty close to full capacity for a 6.6 kW charger. Still waaaay faster than 120V, which is what we are trying to provide. Plus who wants to carry around anything heavier than 10 Ga wire. 8/3 is pricier and heavier.

We weren't trying to create a charger which can handle every situation, we shot for a low cost highly portable, safe way to allow for L2 charging when away from home over at a friends or family member's house. My situation, for example: My parents live 63 miles away in Columbia, TN. Almost all of it interstate at 70 mph. They don't have an ESVE obviously, but they do have a 240 tanning bed outlet in their garage. I've never taken the LEAF down there because it would take 17 hours to charge at 120 and I'm obviously not staying that long for a day trip when the family and I visit. Now I can take the LEAF down because I can charge in 6 hours, which is definietly in my timeframe for visiting, or just maybe 2 hours if I really needed to get back sooner because there is a L3 charger at Nissan NA in Franklin,TN which can get me enough juice to get home with roughly a 20 minute charge. This is what we are shooting for. I understand that the newer leaf is supposed to be getting a 6.6 kw charger, but you don't necessarily have to have 6.6kW while using a portable charger on the road. 6kW should be just fine. If NEMA had a 40 amp twist lock connector power wouldn't be a problem, but as far as I know they don't. Even if they did it would probably cost $100 just for the female socket.