My L1 ESVE findings.....

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jwallace3

Well-known member
Joined
Apr 28, 2011
Messages
156
Location
Tennessee
I'm an electrical engineer and have been looking for a cheap easy way to mod the panasonic esve that comes with the leaf to allow for L1 or L2 charging. Mainly so I can visit my parents down in Columbia, TN and I live in Springfield, TN which is about 64 miles each way. Anyway, I successfully made a small wiring mod last night which consisted of me changing out the 120 volt pigtail to a 240 pigtail I made and running a jumper on the inside of the unit. This will allow me to put it all back to the original setup if I need to for some other reason. Utilizing another pigtail which plugs into my new pigtail I mounted the unit I can also charge legacy L1. The entire circuit board is sealed in a rubber like potting material so I'm trying not to disturb that if possible. I will be working on a little better way to complete the 240/120 mod since the way I have it right now disables some of the safety features of the unit. I did charge successfully from 3 bars to 12 last night in 7 hours so a little slower than the 16 amp charging which would have taken about 5 or so. I will also be working on an easy way to extend the pulse width of the 1kHz square wave to allow for full 16 amp charging instead of the 12 amp that I'm currently charging at. Since I'm not modifying the existing electronics, I will probably be using a small micro to do an input capture of the pulse and extend the pulse with my micro. Space is the main constraint so it will have to be a small micro with that functionality. So just a heads up for those interested I will be posting my final results once I clean up the process and have good pics with instructions. Also as a heads up I'm currently working with my alma mater (Western Kentucky University) engineering department and am advising on a senior project to develop a portable, inexpensive 120/240 esve with 12-20 amp functionality. After the prototype is perfected they will be manufacturing some units for sale on a case by case basis. We expect the final cost to be betweek $400-$800 depenedent completely upon how inexpensive we can find the J1772 connector from a manufacturer. Please email or PM with any questions.
Jack
 
If anyone knows where I can locate a schematic for this unit the mod would take a less time and I would be able to implement all safety features except for current leakage detection. That would only be available @ 120 charging. This is because they have a CT with the 120 hot and neutral passing though it. At 120 the current must return so the sum of the currents passing through the CT will be zero unless there is a current leakage somewhere. At 240 , however, there is no return path. All of the current is consumed by the charger so this CT method doesnt work and would have to be disabled durning 240 charging.

Edit: This statement is completely wrong. I was tired and had a crying 4 month old when I wrote this. Obviously not thinking. Please ignore.
 
You do realize, I assume, that Ingineer did this conversion quite some months ago - while maintaining all of the safety features - and has been selling a 120/240 variable current upgrade for the Panasonic ever since... For what little he charges, it hardly seems worthwhile reinventing the wheel.

jwallace3 said:
I'm an electrical engineer and have been looking for a cheap easy way to mod the panasonic esve that comes with the leaf to allow for L1 or L2 charging. Mainly so I can visit my parents down in Columbia, TN and I live in Springfield, TN which is about 64 miles each way. Anyway, I successfully made a small wiring mod last night which consisted of me changing out the 120 volt pigtail to a 240 pigtail I made and running a jumper on the inside of the unit. This will allow me to put it all back to the original setup if I need to for some other reason. Utilizing another pigtail which plugs into my new pigtail I mounted the unit I can also charge legacy L1. The entire circuit board is sealed in a rubber like potting material so I'm trying not to disturb that if possible. I will be working on a little better way to complete the 240/120 mod since the way I have it right now disables some of the safety features of the unit. I did charge successfully from 3 bars to 12 last night in 7 hours so a little slower than the 16 amp charging which would have taken about 5 or so. I will also be working on an easy way to extend the pulse width of the 1kHz square wave to allow for full 16 amp charging instead of the 12 amp that I'm currently charging at. Since I'm not modifying the existing electronics, I will probably be using a small micro to do an input capture of the pulse and extend the pulse with my micro. Space is the main constraint so it will have to be a small micro with that functionality. So just a heads up for those interested I will be posting my final results once I clean up the process and have good pics with instructions.
 
I do. I just didn't feel like paying $240+ for this conversion when I can do it for $20. Plus being an electrical engineer, I just wanted to see how they did it and make the mod myself. Just like when I built an electric 36 volt 4 wheeler for my daughter, instead of buying a motor controller, I designed my own and had the board cut and components mounted by my friends at the university who have surface mount capability. It's just part of my curiosity and creativity and the info that I will post is for the rest who are like me who just want to do it themselves for the challenge. Also, my mod doesn't change any internal components or firmware. I am adding components to the existing package, so one could in theory remove those extra componets and return the internals to the factory setup and re-seal. Technically opening the unit voids your warranty, however, they wouldu never be able to tell that the unit was every modded with my method if you re-seal the unit properly.

TomT said:
You do realize, I assume, that Ingineer did this conversion quite some months ago - while maintaining all of the safety features - and has been selling a 120/240 variable current upgrade for the Panasonic ever since... For what little he charges, it hardly seems worthwhile reinventing the wheel.

jwallace3 said:
I'm an electrical engineer and have been looking for a cheap easy way to mod the panasonic esve that comes with the leaf to allow for L1 or L2 charging. Mainly so I can visit my parents down in Columbia, TN and I live in Springfield, TN which is about 64 miles each way. Anyway, I successfully made a small wiring mod last night which consisted of me changing out the 120 volt pigtail to a 240 pigtail I made and running a jumper on the inside of the unit. This will allow me to put it all back to the original setup if I need to for some other reason. Utilizing another pigtail which plugs into my new pigtail I mounted the unit I can also charge legacy L1. The entire circuit board is sealed in a rubber like potting material so I'm trying not to disturb that if possible. I will be working on a little better way to complete the 240/120 mod since the way I have it right now disables some of the safety features of the unit. I did charge successfully from 3 bars to 12 last night in 7 hours so a little slower than the 16 amp charging which would have taken about 5 or so. I will also be working on an easy way to extend the pulse width of the 1kHz square wave to allow for full 16 amp charging instead of the 12 amp that I'm currently charging at. Since I'm not modifying the existing electronics, I will probably be using a small micro to do an input capture of the pulse and extend the pulse with my micro. Space is the main constraint so it will have to be a small micro with that functionality. So just a heads up for those interested I will be posting my final results once I clean up the process and have good pics with instructions.
 
jwallace3 said:
I would be able to implement all safety features except for current leakage detection. That would only be available @ 120 charging. This is because they have a CT with the 120 hot and neutral passing though it. At 120 the current must return so the sum of the currents passing through the CT will be zero unless there is a current leakage somewhere. At 240 , however, there is no return path.
Not sure I understand this... Why wouldn't there be a return path at 240V; doesn't "no return path"=="open circuit"? Why wouldn't all the current flowing out on pole return through the other pole, thus creating a sum of zero at the CT regardless of the voltage. The fact that one pole is neutral at 120V while that same pole is another hot at 240V should make no difference. Current which goes somewhere else but flow through the two wires is by definition leakage, no?
 
Yes,
this should be the case, however, the charger doesn't like single phase 240 going through the CT. It thinks there is a current leak. I am still working out the issues. Breaking out my power book. It's been a while, I am a power engineer, so I'm used to dealing with 3 phase. Single phase is different because 240 is single phase with a center tap on the secondary. I

tps said:
jwallace3 said:
I would be able to implement all safety features except for current leakage detection. That would only be available @ 120 charging. This is because they have a CT with the 120 hot and neutral passing though it. At 120 the current must return so the sum of the currents passing through the CT will be zero unless there is a current leakage somewhere. At 240 , however, there is no return path.
Not sure I understand this... Why wouldn't there be a return path at 240V; doesn't "no return path"=="open circuit"? Why wouldn't all the current flowing out on pole return through the other pole, thus creating a sum of zero at the CT regardless of the voltage. The fact that one pole is neutral at 120V while that same pole is another hot at 240V should make no difference. Current which goes somewhere else but flow through the two wires is by definition leakage, no?
 
There is one safety feature that I'm not sure how it can be implemented at 240. The panasonic ESVE checks to see if ground and neutral are tied together to tell the unit that the circuit is properly grounded. At 120 the existing cable has hot, neutral, and ground. If you look at any 240 charger there is still only 3 wires hot 1, hot 2, and ground. So if you modify the panasonic ESVE for 240 charging there is absolutely no way with 3 wires that this feature can be implemented because the charger would be checking to see if the previous neutral terminal (now hot/phase 2) is tied to ground. This would be a bolted fault which would trip the breaker in your panel. So this feature has to be bypassed unless you add a third relay and use a 4 wire nema 14 connector to accomplish this. But with a 3 wire nema 6 it's just not possible. I am just doing this for fun at the moment. Its actually a lot easier to just build a whole new charger. I have the SAE J1772 standard I could probably build a 120/240 universal charger prototype in a day if I had the relays I need on hand. I am letting the students at Western build one because its a good engineering exercise to design based off of a standard. I will probably go ahead and build one myself and use my current J1772 connector from my panasonic ESVE. I typically use freescale microprocessors for projects like this since it has plenty of features and is relatively cheap, but the logic required for the J1772 standard is so simple I may just use a picaxe or something of that nature. Also, the panasonic ESVE uses a transformer and bridge rectifier for the electronics DC. This is kind of an outdated method. A rectifier and swithing power supply with a closed loop control system is the cheapest way to go plus it can adapt to any input AC voltage in the design window, ie 120-240 vac. This is probably the way I will go.
 
You can buy a controller already, and add the contactor, power supply, J-1772 cable and case... http://modularevpower.com/EVSE_module_3.htm" onclick="window.open(this.href);return false;

Of course thats probably more than you want to spend for the controller.

At this point, there are the Aerovironment units on eBay for $599, the Schnieder is at Home Depot for $729, the SPX PowerExpress (which has an adjustable Pilot signal, 12A/16A/24A/32A) is $749.

I don't think its worthwhile from a cost perspective any longer. If you want to to it for other reasons, thats fine, but you're not going to save much money building your own EVSE, once you factor in your labor.
 
jwallace3 said:
I'm an electrical engineer and have been looking for a cheap easy way to mod the panasonic esve that comes with the leaf to allow for L1 or L2 charging.
Jack
Good deal Jack. One thing I don't hear anyone talking about is the EVSE temperature after some period of charging. Last night I took my Ingineer modified, 240v, 12a Panasonic EVSE and decided to charge my car from 1 bar to 12 bars at about 75% of the Blink charge rate. I did this test because I just had my car software upgraded (from a 1-4-11 purchase date) and I was hoping to reset the range-o-meter (with no practical reason to justify why it might do so) since I usually charge to 80% every day and only charge to 100% once per month.

I must say I'm very disappointed in the software upgrade. The range-o-meter AND the bars indicate I can't go as far as I've been going on a charge (the range-o-meter lost 1 bar and 6 miles from what I had been getting - oh the pendulum always swings too far when you get a rash of complaints on anything it seems).

Anyway, the temperature of the bottom of the EVSE sitting on a towel got to 129 deg F within two hours of charge start (240v, 12a) and had risen to 136 deg F at the end of the 6 hour charge cycle. That's measured on the outside of the package! I was thinking about upping the EVSE to 16a with Phil's additional upgrade but now I'm concerned about the temperature of the unit if I do so. At this point I need to test it at 120v, 12a to see what temp it gets to but I was surprised it got so high. This says the losses in the unit are greater than I expected. Hmmm...

Malcolm :geek:
 
Yes, the firmware upgrade takes some off the top but gives it back to you at the bottom end int the form of a hidden "reserve". When you get low and it says you've got about 8 miles left, it's really more like 15.

As for temperature of the modified EVSE, Ingineer's done fairly extensive torture testing at significantly higher than 16a. It doesn't get much hotter than that. Lots of us have done it, you'll be fine.

I'm no electrical engineer, but this talk of jumpering things seems strange. Ingineer actually depotted the entire board and found it was all ready for 240v except for a couple components that were rated at 120v. How can you do this without replacing those components or running them way over spec (which doesn't seem safe)? Anyhow, you're free to do whatever you want with your own unit, of course. ;)
 
I am not trying to reinvent the wheel or anyting. Ingineer has a great product. I am just posting results of my own mod that is inexpensive for those who are wanting to try it themselves. To build one from scratch costs less than $50 for the electronics and such, the connector is the main cost. I don't plan on using my modified ESVE for long for portable charging,it is just a quick fix for my current needs and maybe others would have this same need for a quick $20 fix to get 240V 12 amp charging with their current unit.

My 240/120 universal portable unit I'm helping develop with the university is basically a good exercise for aspiring engineers in school to design something based on a specification that is standard based. The result should be a relatively inexpensive portable charger based on the J1772 standard. The standard actually doesn't call for portable L2 charging ESVE at all. L2 according to the standard is dedicated. So any portable L1/L2 universal type charger deviates from the standard, but will still abide by the standard and be completely compatible. There may be cost competitive units available on Ebay or wherever else, but if all engineers just sat around and said somebody else already did it, we wouldn't have anything new. Improvement is what we are striving for and like I said, it's an exercise for young engineers in school. The outcome should be exciting. With the standard and a few relays, resistors,diodes and a micro, I can build one from scratch with some assembly code building.

The $20 dollar fix is for those who need a quick, portable option that's cheap and easy to perform. It involves changing out the pigtail and running 2 jumpers. Quick and easy. Not a good permanent solution, but for some, it may meet their imediate needs. Details to come with pics. It's about a 20 minute operation for those that are interested.

I expect our university design to be about half the size of the panasonic unit. The first generation will just have 4 LEDs for indication, but I plan on adding a small screen and some buttons for navigation and control. I want to add metering functionality so that if you are at a friends house or even at work and want to re-imburse that person(s) for some reason you can enter their KWhr rate and get a cost for your charge at that location. Not for everybody, but I think it would be neat and the students are very excited about it. I have 2 of the best in the program to guide in the development of this device.
 
Everything is rated for 250VAC, just not the electronics that support it. If you de-pot the board it can never go back to panasonic for warranty work. Using my method, theoretically you could remove the jumpers and pigtail and send it back as it was originallly manufactured. like I said, this is a quick fix, not a permanent one. Ingineer has a good product, I'm not trying to replace it. This is a fix for those who don't have the time for all the sending and receiving of units and just needs 240 portable charging now.

GeekEV said:
Yes, the firmware upgrade takes some off the top but gives it back to you at the bottom end int the form of a hidden "reserve". When you get low and it says you've got about 8 miles left, it's really more like 15.

As for temperature of the modified EVSE, Ingineer's done fairly extensive torture testing at significantly higher than 16a. It doesn't get much hotter than that. Lots of us have done it, you'll be fine.

I'm no electrical engineer, but this talk of jumpering things seems strange. Ingineer actually depotted the entire board and found it was all ready for 240v except for a couple components that were rated at 120v. How can you do this without replacing those components or running them way over spec (which doesn't seem safe)? Anyhow, you're free to do whatever you want with your own unit, of course. ;)
 
So I'm hearing a couple of things here that I'd like to expand on:

1. The OP said that all components inside are rated at 250V AC. I'm hearing that Phil has to depot the board to replace a couple of under-rated components (the 2 relays?). But then in another thread, chris1howell said that those relays are rated at 240V 20A and are not replaced as a response to garygid and darkstar saying that the relays are replace. So I'm a bit confused here. Did Phil have to replace any potted components or not? If not, then why were there talk of Phil having to depot the circuit board, which is why his upgrade is expensive, due to the depotting/repotting labor?

2. The OP said your jumper approach bypasses a few of the safety features. Can you elaborate on what safety feature(s) were bypassed exactly? How important are they? And what are the risks of bypassing them?

3. I also heard that Phil replaced the transformer with a universal dc power supply that can accept either 120V or 240V. So how does a jumper cable allow the unit to automagically accept 240V input?

4. The OP keeps saying that his solution is a temporary solution and not a permanent solution. But then he said he could charge from 3 bars to 12 bars with the jumper approach just fine. So why is it a temporary solution only? What are the drawbacks?
 
jwallace3 said:
There is one safety feature that I'm not sure how it can be implemented at 240. The panasonic ESVE checks to see if ground and neutral are tied together to tell the unit that the circuit is properly grounded. At 120 the existing cable has hot, neutral, and ground. If you look at any 240 charger there is still only 3 wires hot 1, hot 2, and ground. So if you modify the panasonic ESVE for 240 charging there is absolutely no way with 3 wires that this feature can be implemented because the charger would be checking to see if the previous neutral terminal (now hot/phase 2) is tied to ground. This would be a bolted fault which would trip the breaker in your panel. So this feature has to be bypassed unless you add a third relay and use a 4 wire nema 14 connector to accomplish this. But with a 3 wire nema 6 it's just not possible.
I'd love the see Phil comment on this (if he reads this), and how he addressed this issue in his evseupgrade mod.
 
leafme said:
Anyway, the temperature of the bottom of the EVSE sitting on a towel got to 129 deg F within two hours of charge start (240v, 12a) and had risen to 136 deg F at the end of the 6 hour charge cycle. That's measured on the outside of the package! I was thinking about upping the EVSE to 16a with Phil's additional upgrade but now I'm concerned about the temperature of the unit if I do so. At this point I need to test it at 120v, 12a to see what temp it gets to but I was surprised it got so high. This says the losses in the unit are greater than I expected. Hmmm...

Malcolm :geek:
When I tried my Rev2 mod, it ran pretty hot to me, too. I didn't have anything to measure the temperature with, but it was hot to the touch and you wouldn't want to touch it for more than a few seconds. However, when I asked Phil whether I should put a small fan on the box to keep it cool or not, he said no, that'd be wasteful to do. He said the upgraded EVSE will last longer than the lifetime of the car even with daily use.

Usually electrical components are rated at least at 60C (140F), so I guess while it may feel hot for us to touch, it may still be OK for the components.
 
jwallace3 said:
the charger doesn't like single phase 240 going through the CT. It thinks there is a current leak. I am still working out the issues.
Just my guess, it thinks there is leakage current because there is leakage current

One of the reasons they worry so much about the ground integrity and detecting leakage currents is that the car is a metal enclosure which is normally insulated from ground by it's tires until it receives a ground through the EVSE, so they are super paraniod about grounding and leakage in EVSE design.
 
Fair enough! As an EE myself, I can appreciate that!

jwallace3 said:
I do. I just didn't feel like paying $240+ for this conversion when I can do it for $20. Plus being an electrical engineer, I just wanted to see how they did it and make the mod myself.
 
The general rule of thumb is that, if you can keep your hand on it for 5 seconds, it is not too hot.

Volusiano said:
Usually electrical components are rated at least at 60C (140F), so I guess while it may feel hot for us to touch, it may still be OK for the components.
 
I'm with jwallace3 and I hope to learn more. I really want to know what it takes to change the duty cycle of the pilot signal quickly and easily. I really don't think it is a firmware hack.

As for the CT, 240V shouldn't affect it unless there really is a current leak. for 120, neutral and ground should never be connect anyways right?

I'm going to try it as soon as it get one.

jwallace3 please continue and you don't have to keep justifying to people with more money than brains.
 
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