My L1 ESVE findings.....

lincomatic said:

Hmm.. I saw your post in a different thread, about generators, where you mention that the EVSE checks to make sure gnd and neutral are connected together...

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Do we know exactly how the EVSE checks for ground continuity?

Jack, Thanks for all your efforts on this and sharing it openly...

I will be keeping an eye on the progress.

mxp said:

Jack, Thanks for all your efforts on this and sharing it openly...
I will be keeping an eye on the progress.

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+1!

Thanks for sharing this openly Jack!

Full disclosure I have not opened my Nissan EVSE and am not an EE (although I play one on TV)...

Pictures from http://www.mynissanleaf.com/viewtopic.php?f=26&t=2633

I have to agree with lincomatic, the optimal way to upgrade the Nissan EVSE and likely what Phil at evseupgrade.com is doing is to replace the 120V only transformer (2nd picture) with a universal switch mode power supply. Doing so will change the output from AC to DC requiring depoting of the board to bypass the rectification diodes. There may or maybe not be other components which require upgrade due to the voltage increase. As mentioned in other posts the relays do not require upgrade as they are rated at 250V @ 20A (picture 4).

Powering the mainboard on 120 and bypassing 240 to the relays is a bit messy, while it would work I wouldnt do it...Doing it the right way may cost $30 instead of $20 and all the safety features would remain.

I believe the ground check uses the 3rd smaller relay (3rd picture far right) to pass a small current from L1 Hot to ground through a 5k or so resistor. If you listen carefully you can hear a clicking right after connection before the main relays engage. I do not think it is checking to see if Neutral and Ground are tied together only that there is a path to ground. Routing current through the 5k resistor would be enough to cause a ground fault so.... my theory is the EVSE powers the 3rd relay causing current to flow to Ground causing the GFCI to read a fault if so, ground and the GFCI CT coil is good. If ground is bad no current flows and the GFCI does not read a fault and the EVSE goes into Fault state.

The diodes for AC rectification should not need changing.

Yes, a "universal" DC supply replaces the AC transformer.

The input pigtail and plug are replaced.

Testing is probably done before and after the Mod.

At least one component apparently needs replacing for reliable 240v operation ...
maybe a surge protection that was across the two input power lines?

My digikey parts have arrived so I will be trying the retrofit tonight. Will post results as soon as it's tested and perfected with all safetly features in place.

jwallace3 said:

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.

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.

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Very cool jwallace3! Thank you for having the desire and expertise required to investigate this and thank you for being so willing to share your findings here with the community. I look forward to reading more of your posts.

I guess I'd be more interested in this upgrade except one issue. In the 6 months I've owned my leaf I've only charged it away from home 1 time at a family members home, and even then I didn't really need the charge but wanted to feel a bit safe since it was a long drive home. The thing is, even if I had wanted to charge at 240 Volts, there is nowhere I would have been able to find it unless I had started poking around their home looking for appliances that might use it that I could unplug.

Now, if I wanted to use it at my own home, I could certainly run a 240V plug somewhere in my garage. So I could see doing this mod as a cheap substitute for a wall-mounting EVSE. I just can't see the usefulness as an away-from-home EVSE.

I fully support DIY efforts like this, but I'd like to issue a warning that this modification as presently implemented defeats the GFCI function of the EVSE and could result in electric shock or death by electrocution in the event of a mishap. This is why the SAE (Society of Automotive Engineers) developed a safe standard fro charging EV's and didn't just install a standard plug on them.

EV's are used outdoors, and it's very likely you will at some point connect to something where one or more components are wet. I strongly recommend you do not use any EVSE where the safety has been compromised intentionally. If someone's child plays with your charge cord and gets killed and you knowingly installed a dangerous cord with the safety circuits intentionally bypassed, you could be in big trouble!

The other thing is that one of the 240v legs in the J1772 end is hot all the time, and is not shut off when the handle release button is pulled. In fact, the only way to shut this off is to cut power to the mod. Not very safe at all! The SAE J1772 spec requires that ALL AC power lines be isolated when the pilot signal load is de-asserted by the car.

You just spent many thousands of dollars on your LEAF purchase or lease, I wouldn't sacrifice a few dollars for safety.

I also think any Electrical Engineers that publish details on how to defeat safety circuits are doing a disservice to their profession and the public in general.

-Phil

chris1howell said:

I believe the ground check uses the 3rd smaller relay (3rd picture far right) to pass a small current from L1 Hot to ground through a 5k or so resistor. If you listen carefully you can hear a clicking right after connection before the main relays engage. I do not think it is checking to see if Neutral and Ground are tied together only that there is a path to ground. Routing current through the 5k resistor would be enough to cause a ground fault so.... my theory is the EVSE powers the 3rd relay causing current to flow to Ground causing the GFCI to read a fault if so, ground and the GFCI CT coil is good. If ground is bad no current flows and the GFCI does not read a fault and the EVSE goes into Fault state.

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I thought about that, but wouldn't that cause an upstream GFCI outlet which was supplying the EVSE to trip? My calcuation is that 5K would cause 24 mA to flow, which would definitely cause the GFCI to trip out. I'm guessing the current which is injected comes from the secondary of the 20 volt transformer. With this isolated source, they could put current into the ground, splitting the return current equally on the line and neutral, thus allowing a flow of current to test ground continuity while maintaining current balance on the L and N to prevent tripping upstream GFCI.

Edit: Now I think of it, that wouldn't work. Since return current it the same phase in L and N, it would add rather than cancel to zero in the CT core, so it would cause the external GFCI to trip...

+10

I find this thread title to be misleading, it should be called " How to make a dangerous simple hack" Professional engineers NEVER recommend or encourage such modifications, this is not only extremely dangerous it is irresponsible and shows a lack of judgement and disregard for the safety of others and their property. To encourage general users to do such things is not only irresponsible but a liability. Professional product engineers with years of experience not only understand the time involved to do things properly but take the time to insure all details are addressed and go to lengths to insure their designs are well thought out, fully tested and in the customers best interest. This type of suggestion jeopardizes people, property and the health of the EV movement in general and encourages individuals to do things that they may not be qualified to do by over simplifying the process.

In regards to manufacturing new EVSE units, anyone that wants to build and sell a safe, reliable and UL (or not) listed EVSE to sell on the open market without a budget of about $300K or more, I say good luck! Lets not forget the customer support, economies of scale, distribution, etc, etc.

Ingineer said:

I fully support DIY efforts like this, but I'd like to issue a warning that this modification as presently implemented defeats the GFCI function of the EVSE and could result in electric shock or death by electrocution in the event of a mishap.

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This really tells me all I need to know about this modification... and since I DON'T know what I am doing I would only entrust my EVSE to someone who has made a modification that doesn't compromise any of the safety features. In other words, evseupgrade.com is the only source I would use if I wanted 240 volt charging from the Panasonic L1 charging dock. Saving a bit of money in this case is penny wise and pound foolish.

Whoa! Folks need to take a stress pill and sit down. JWallace hasn't given instructions or suggested that anyone else do anything yet. He's just described (in general) what he's done so far and stated an intention to come up with a DIY project that parts out cheaply. At least wait until he tells someone to do something dangerous before jumping on him.

+10 Yes, everyone, take a chill pill. As davewill pointed out, he's not advising anyone to do what he's done. Please don't run him off the board before he has a chance to finish his mod.

davewill said:

He's just described (in general) what he's done so far and stated an intention to come up with a DIY project that parts out cheaply.

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Yes, but he has apparently done something that defeats one of the key safety features of the EVSE. Telling other people you have done that isn't a way to build confidence. Perhaps rather than describing that he should wait until he has a modification that is safe.

davewill said:

Whoa! Folks need to take a stress pill and sit down. JWallace hasn't given instructions or suggested that anyone else do anything yet. He's just described (in general) what he's done so far and stated an intention to come up with a DIY project that parts out cheaply. At least wait until he tells someone to do something dangerous before jumping on him.

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I agree. I am pretty sure Jack would find a way to add the safety features back if he ever were to provide instructions on how to do the mod.

The parts are not the expensive part.

Having a GOOD design, getting the RIGHT parts, and the LABOR of doing the work properly and competently are a lot of what you are paying Ingineer for.

However, if you are competent to evaluate the design of the modification, obtain reliable parts, do the work, check for errors, and test your work, then ... go for it.

I prefer to have a skilled surgeon do my operation, not use my steak knife and a flashlight.

Regarding figuring out how the EVSE does its ground check. We have two theories 1) it checks if ground and neutral are tied together 2) it simply checks to see if current will flow to ground.

One way to rule out (1) is to test by connecting the ground pin to an earth ground rather than the ground wire in the socket, and seeing if it throws a fault. If it doesn't, then it's not checking to see if ground and neutral are shorted together, and powering the controller board via a H-G-H setup should work OK w/o throwing a fault.