Weekend(s) Project - DIY EVSE

[Ingineer]

I have run many tests on the LEAF, Including charging down to 90 volts, and have not seen anything over 12.5 amps (and that was only transient). I have never seen 17 amps! I find this hard to believe given the architecture of the charger. The primary transformer winding is optimized for 200v 16a charging, so when you run them at 100v, you get very high duty cycles on the primary switch to keep the output high enough to deliver the required voltage to the pack. This means there simply isn't enough headroom to go much higher at these low input voltages. It would be difficult to design a charger that can deliver high power levels at this wide a voltage swing, so they simply don't. You can't trust a cheap Kill-a-watt meter to be accurate, I have seem them wildly inaccurate when exposed to harmonic distortion and non-unity power factors.

Keep in mind the Japanese market LEAFs routinely charge at 100/200v, which is what Nihicon designed the charger for originally.

-Phil

 

[DaveEV]

As gary mentioned the button on the handle does not stop charging as recommended by J1772

Are you sure about that? We discussed this, but there was no conclusion. You WOULD be in a good position to have verified this. It would be a significant fault on the car's part if it didn't.

Yeah, I thought someone confirmed with their Blink that if you push the button current stops getting pulled, but the contactors/relays in the Blink stay shut until the plug is removed. Will have to confirm this by watching the electricity meter while holding the button (need 2 people!)

 

[davewill]

Yeah, I thought someone confirmed with their Blink that if you push the button current stops getting pulled, but the contactors/relays in the Blink stay shut until the plug is removed. Will have to confirm this by watching the electricity meter while holding the button (need 2 people!)

Well, I can confirm THAT, but the spec doesn't say that the car has to open the EVSEs contactors (which couldn't happen quick enough anyway), just that it has to stop drawing current when the trigger is pressed.

 

[Ingineer]

The LEAF will not charge and will cease drawing any appreciable current when the handle interlock is de-asserted. If it doesn't, I'd call Nissan immediately, as this could harm your car and/or EVSE.

-Phil

 

[chris1howell]

It's good to know the LEAF is not pulling current when the button is pressed, my observation was based on the relays not opening...

 

[Ingineer]

The Relays don't open to prevent contact arcing, which in the relays could cause a welded contact fault which would be extremely dangerous.

This is why the handle interlock signal is fed to the on-board charger rather then the EVSE. It stops drawing current, so there will be no significant damage to the pins and sleeves in the J1772 connectors.

Keep in mind the contact surface area in the connectors is much larger than in the relays, so if there is any possibility arcing over time, it would be best to have it there rather than in the relays. Relays could weld on, whereas this will never happen in the connector.

-Phil

 

[lincomatic]

...
- As gary mentioned the button on the handle does not stop charging as recommended by J1772.
...

Are you sure about that? We discussed this, but there was no conclusion. You WOULD be in a good position to have verified this. It would be a significant fault on the car's part if it didn't.

I just tested it w/ the DIY EVSE using the ITT J1772 cable. The confusion lies in the fact that when you press the button on the connector, the car stays in State C, the J1772 charging state. Since it's in State C, an EVSE will still have the relay contacts closed, and the status indicated on an EVSE's status lights/display wil still indicate charging. However, the car stops drawing current as when the button is pressed, and doesn't switch out of State C until the plug is disconnected from the car. I measured the current with an AC current clamp meter, and the current drops the instant the button is pressed. This is safer than only relying on the EVSE to open the contacts, in case the EVSE malfunctions, and also prevents arcing of the relay contacts.

 

[Ingineer]

That's what I just said...

 

[TEG]

I just tested it w/ the DIY EVSE using the ITT J1772 cable. The confusion lies in the fact that when you press the button on the connector, the car stays in State C, the J1772 charging state. Since it's in State C, an EVSE will still have the relay contacts closed, and the status indicated on an EVSE's status lights/display wil still indicate charging. However, the car stops drawing current as when the button is pressed, and doesn't switch out of State C until the plug is disconnected from the car. I measured the current with an AC current clamp meter, and the current drops the instant the button is pressed. This is safer than only relying on the EVSE to open the contacts, in case the EVSE malfunctions, and also prevents arcing of the relay contacts.

And the Leaf still shows charging indication on the dashboard even though it stopped drawing current which I find annoying.
I was concerned that you could "pull a prank" on someone by just pressing the button on their J-plug without pulling it out, then walk away and they would think it was still charging (by the indicator lights) when it is no longer. But I was told (but haven't confirmed) the following:
#1: The messaging to a phone app to say that charging has stopped will be triggered.
#2: The car will resume charging automatically after some amount of time left in the "I think you intend to unplug soon" state.

Anyone know how long it stays in the "charging suspended" state until it automatically resumes?

 

[lincomatic]

That's what I just said...

I think your messages above came through as I was typing mine!

 

[chris1howell]

I love this place, lots of really smart people....

 

[davewill]

... I was concerned that you could "pull a prank" on someone by just pressing the button on their J-plug without pulling it out, then walk away and they would think it was still charging (by the indicator lights) when it is no longer. But I was told (but haven't confirmed) the following:
#1: The messaging to a phone app to say that charging has stopped will be triggered.
#2: The car will resume charging automatically after some amount of time left in the "I think you intend to unplug soon" state.

Anyone know how long it stays in the "charging suspended" state until it automatically resumes?

You get no charging stopped/complete message unless you actually unplug. It should start up again almost immediately upon releasing the button. The only way you could truly play such a "joke" would be to jam the button so it stayed pressed. I don't intend to sit up late worrying about that possibility.

 

[ebill3]

... I was concerned that you could "pull a prank" on someone by just pressing the button on their J-plug without pulling it out, then walk away and they would think it was still charging (by the indicator lights) when it is no longer. But I was told (but haven't confirmed) the following:
#1: The messaging to a phone app to say that charging has stopped will be triggered.
#2: The car will resume charging automatically after some amount of time left in the "I think you intend to unplug soon" state.

Anyone know how long it stays in the "charging suspended" state until it automatically resumes?

You get no charging stopped/complete message unless you actually unplug. It should start up again almost immediately upon releasing the button. The only way you could truly play such a "joke" would be to jam the button so it stayed pressed. I don't intend to sit up late worrying about that possibility.

I watched current on a Kill-A-Watt. Current dropped to almost zero immediately after pressing the button and very quickly started to ramp up after release. In 15 seconds it was back to 12 Amps or so. Correct - no message.

Bill

 

[Volusiano]

The only way you could truly play such a "joke" would be to jam the button so it stayed pressed. I don't intend to sit up late worrying about that possibility.

Don't need to jam the button. A simple wrap around with a piece of tape or string will do. Or maybe a rubber band.

 

[lincomatic]

The only way you could truly play such a "joke" would be to jam the button so it stayed pressed. I don't intend to sit up late worrying about that possibility.

Don't need to jam the button. A simple wrap around with a piece of tape or string will do. Or maybe a rubber band.

With the ITT connector, once you press it, it stays disengaged until you unplug it and plug it back in. I haven't tested w/ the Nissan Yazaki plug. That one will re-engage when you let off the button?

 

[davewill]

With the ITT connector, once you press it, it stays disengaged until you unplug it and plug it back in. I haven't tested w/ the Nissan Yazaki plug. That one will re-engage when you let off the button?

Ouch! That would be a problem since any curious 8 year old could ruin your day. Anyway, yes both the one on the Nissan EVSE and the Blink reengage as soon as you let go.

 

[lincomatic]

With the ITT connector, once you press it, it stays disengaged until you unplug it and plug it back in. I haven't tested w/ the Nissan Yazaki plug. That one will re-engage when you let off the button?

Ouch! That would be a problem since any curious 8 year old could ruin your day. Anyway, yes both the one on the Nissan EVSE and the Blink reengage as soon as you let go.

Update: I played with it a bit more... if you pull up on the handle the button pops back out. I just remembered that when I first got this cable, I had a lot of trouble releasing it from the car, and had to give it a hard upward tug. So mine might be a bit out of spec, and the typical ITT connector may not behave the same way as mine.

 

[QueenBee]

That's what I just said...

Thank you guys for the explanation about this feature. This all makes perfect sense now.

 

[garygid]

My mistake about pressing the Release button, I fixed my post.
I should have tested these things myself.

Thanks all who actually checked the current.

 

[omkar]

Bluetooth SPP working to read and update settings (including charge current). Now I just need to figure out how to write and app for Android...

Very impressive chris! This looks fantastic - hope to hear more updates!