Weekend(s) Project - DIY EVSE

[Ingineer]

I had the opportunity to connect my project to an Oscilloscope today and test the different PWM duty cycles and Voltage outputs. The Pilot signal was measured at 984.3Mhz.

I assume you mean Hz, correct? 1 Ghz isn't going to work!

 

[DarkStar]

Lookin' great!

I'm getting a PWMPAL from Parallax and will be using that with an existing BASIC stamp (BS2) I already have to generate my PWM signal. I also decided to bite-the-bullet and buy a small digital oscilloscope (not very high resolution, but good enough for control pilot signals)...

 

[chris1howell]

Good catch... you are correct it was 984.3Hz.

 

[chris1howell]

I almost bought that same scope last week (gotta love SparkFun), until I found one to test with. I would love to hear how you like it after you have played with it a bit...

 

[DarkStar]

I almost bought that same scope last week (gotta love SparkFun), until I found one to test with. I would love to hear how you like it after you have played with it a bit...

No problem! I've been sitting on my "Free Day" credit and was waiting to see if SparkFun would be carrying the new DSO Quad before the credit expired... It doesn't look like they'll be picking it up by the end of next week, so I decided to place my order!

 

[Ingineer]

The Panasonic EVSE's PWM is at 1002.3hz according to my NIST traceable frequency counter.

It's right about on the mark with a 200uS low and 800us high which is a 20% duty cycle or 12A according to J1772.

It seems to meet the J1772 spec perfectly except for failing the diode check.

-Phil

 

[garygid]

What does the EVSE do if the car requests charging WITH ventilation?

 

[DaveEV]

What does the EVSE do if the car requests charging WITH ventilation?

It either provides it if it can (triggers a fan if an eclosed area) or denies the charge request if it can't.

 

[garygid]

Sorry, I did not mean "What SHOULD any EVSE do...".

I meant "What does the Panasonic L1 EVSE do?"...
or, your Control Pilot,
or any other EVSE that you can actually test.

 

[chris1howell]

Gary,

If the vent required voltage is detected, the control pilot illuminates the error LED, displays “Error Vent Required” on the LCD (if connected) and does not activate the power relay.

I would be curious to see if the Panasonic unit does the same, this condition should not be very common. I am wondering if they left it out, like it is reported they did with the diode check.

Chris

 

[garygid]

I agree, that is why I asked.

 

[Ingineer]

What does the EVSE do if the car requests charging WITH ventilation?

I just checked this for you Gary; It allows charge. In fact, anything over about 1V up to 7.5v on the pilot line enables charge. Below that gets a blinking fault light. From 7.5v to 11v it performs it's ground/self test, then enables the PWM, but doesn't enable output or change status LEDs.

Really bone-simple implementation. Panasonic should be ashamed of themselves!

Muddy water could definitely enable it, but that resistance would also trip the GCFI for sure, so it's still safe even if they cut a lot of corners!

-Phil

 

[AndyH]

Why would venting need to be implemented for the Leaf? Venting is not required or necessary for sealed packs. The chance that anyone's going to be manufacturing lead-acid EVs anytime soon is slim to none.

 

[garygid]

The issue is not the LEAF, but the EVSE's behavior, because it could be used with any J1772 vehicle.

Perhaps Panasonic (and Nissan?) felt the diode-test was optional in the Standard, and they wanted it to work with "ventilation-required" vehicles?

There is no "For Use Only with the Nissan LEAF" warning on it, nor a
"Caution: This EVSE does Not Comply with all J1772 Safety Standards".

Maybe such warnings appear in the User Manual?

It is nicely compact, but it easily could have been designed to be fully J1772 compliant.

Perhaps this is ONE of the reasons that Nissan so strongly encourages installation and use of another (L2) EVSE?

Perhaps Nissan did not fully anticipate the many owners who intend to use the included L1 EVSE on a daily basis, as their "normal" means of charging?

 

[LEAFer]

Perhaps Nissan did not fully anticipate the many owners who intend to use the included L1 EVSE on a daily basis, as their "normal" means of charging?

+1 !

 

[chris1howell]

This weekend I took 1 step back to take two forward. I went back to the basics, no LCD and a fixed current. I tweaked the circuit a bit to get a perfect 1khz pilot 984Hz was just too close. Also I added GFI detection, all that’s left is the diode detection. I want to achieve a fully compliant J1772 2010 pilot before I start add all the features. My plan is to replace the guts of the Nissan / Panasonic L1 EVSE with my Basic Pilot then build a version with the LCD, selectable current, current and voltage monitoring (to count Kwh added) and maybe even data logging and a network connection. I think I will need a few more weekends... :lol:


Not Connected

Basic Not connected by chris1howell, on Flickr

Waiting

Connected Waiting by chris1howell, on Flickr

Charging

Charging by chris1howell, on Flickr

 

[mwalsh]

This weekend I took 1 step back to take two forward. <snip> . I think I will need a few more weekends... :lol:

Nice work!

 

[DarkStar]

That looks awesome! What are you using for GFI detection? My Mouser-fu (or Digikey-fu if you want) apparently isn't strong enough... Thanks!

 

[chris1howell]

Darkstar, I am currently testing the Honeywell CSLA2CD Sensor Digikey Part# 480-1994-ND.

http://sccatalog.honeywell.com/imc/printfriendly.asp?FAM=current&PN=CSLA2CD

I have the sensor up and reading the zero current value at the microcontroler, I have not yet tested or calibrated the sensitivity.

 

[DarkStar]

I kept looking for GFCI or GFI sensor... Transducer or hall-effect sensor would have made more sense!

For $20, looks like it will be worth playing with!