mux
Posts: 64
Joined: Sat Jan 13, 2018 3:52 am
Delivery Date: 13 Oct 2011
Leaf Number: 6177

I designed and built a 'better' granny charger ('11 leaf)

Sun Mar 18, 2018 5:53 am

First things first, 'better' is of course subjective. It's better for me. Namely:

  • It charges at 16A instead of 10, so as fast as my on-board charger will allow
  • It's lighter and smaller than the stock portable EVSE, most importantly: it now fits in the glove box!
  • It's got a rubber instead of PVC cable, so much less stiff and more durable, while also being slightly smaller in diameter
  • It's got thicker conductor wires (3x2.5mm2/13AWG instead of 3x1.5mm2/15AWG)
  • It's just a cable with a mains plug on one end and J1772 on the other, no big 'box' in the cable
  • I have full control over the design, i.e. I can change stuff if I want (and I will)

I did this by designing a custom controller board that fits inside an Aliexpress-sourced Duosida SAE J1772 plug. It was a proper struggle to get it all in. Nonetheless this was successful, and I've used the cable for three full charges of my range-extended 2011 Leaf, meaning it's been hanging on in freezing temperatures and ice rain for at least 24 hours. I call that a win.

https://youtu.be/HV3468LmIiQ

The cable is NOT SAE J1772 COMPLIANT. Let me just be up-front and clear about this. It will fail any sniff test, as the mains plug is more than 30cm from the EVSE control electronics. As I find this stipulation in the rules stupid, I ignored it. Otherwise, it complies with the entire charging standard; it has a GFI safety feature, it switches both live and neutral, the relays are rated over industrial temperature range for the full current, the EVSE electronics are galvanically isolated and the EVSE will latch off on car and EVSE errors. As the connector is not IP-rated, the electronics are conformally coated inside. I should probably pot the electronics.

ToDo list

I don't consider this a 'good' design yet. As you can tell from the video, fitting the board in is fine, but fitting the cables in as well is a struggle. I'm also bypassing the strain relief bracket with a generous amount of hot glue. Lastly, I have already overloaded somebody's home fuses once, as pulling 16A on a single phase maxes out our standard circuits here, and using any big consumer on that group will quickly trip a fuse. So, in a future version, I would probably want to:

  • Make the electronics even smaller
  • Make dedicated routing paths with fastening points for the high power cabling
  • Give it a switch between 10 and 16A
  • Put the LED on top, probably dual-color, bit brighter
  • pot the entire thing inside

I don't think this is viable as a commercial project. I already had to spend about €100 to make this one, which means that if I were to include workmanship and sell the thing, it'd basically be the same price as any other portable EVSE, but then very low volume and made by some schmuck on the internet who barely gives warranty. I wouldn't trust me with that. Nevertheless, if there is enough interest to warrant the time investment, I might try to do a revision and make a couple boards for people to tinker with. Not sure how many people still use granny chargers.

Also: I realize that this is a bit Eurocentric; this lead really only has any right to exist on 208/240V.

jjeff
Posts: 1633
Joined: Wed Jan 13, 2016 9:10 am
Delivery Date: 13 Jul 2014
Leaf Number: 422121
Location: MSP MN

Re: I designed and built a 'better' granny charger ('11 leaf)

Sun Mar 18, 2018 6:18 am

Where are you from? In N. America pre '13 Leafs maxed out at 12a @ L1(120v) and 16a @ L2(>200v) no matter how high your EVSE would go. Also in N. America, pre '15 Leafs all had 12 gauge wire, capable of 20a, it wasn't until '15 Nissan cheaped out and downgraded to 14 gauge or wire capable of 15a max. Of course it could be worse, it sounds like some OEM EVSEs even used 16 gauge wiring :x
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a

mux
Posts: 64
Joined: Sat Jan 13, 2018 3:52 am
Delivery Date: 13 Oct 2011
Leaf Number: 6177

Re: I designed and built a 'better' granny charger ('11 leaf)

Sun Mar 18, 2018 8:00 am

I'm in the Netherlands, all our outlets are 240. So yeah, that makes it a lot less useful in NA. I'm aware of that.

Do you mean the gauge of the wires in the EVSE or in the car?

User avatar
TonyWilliams
Posts: 10066
Joined: Sat Feb 19, 2011 1:48 am
Location: San Diego
Contact: Website

Re: I designed and built a 'better' granny charger ('11 leaf)

Sun Mar 18, 2018 8:49 am

Obviously, as stated above, this project does not meet the requirements of J1772.

But, if you want a US source for this plug, we have them, however we want to be clear that we neither warrant, nor approve, of this type of a project. Injury, fire or death could result from misuse of electricity.

Consult with a qualified electrician or engineer prior to handling electricity.

https://shop.quickchargepower.com/J1772 ... -JP40A.htm

SageBrush
Posts: 2076
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

Re: I designed and built a 'better' granny charger ('11 leaf)

Sun Mar 18, 2018 9:34 am

Mux,
I wish I had your expertise.

Cheers!
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California
Car is now enjoying an easy life in Colorado
3/2018: 58 Ahr, 28k miles

jjeff
Posts: 1633
Joined: Wed Jan 13, 2016 9:10 am
Delivery Date: 13 Jul 2014
Leaf Number: 422121
Location: MSP MN

Re: I designed and built a 'better' granny charger ('11 leaf)

Sun Mar 18, 2018 7:00 pm

mux wrote:Do you mean the gauge of the wires in the EVSE or in the car?

The J1772 cable and power cable to the EVSE from the wall socket, not sure the gauge of wiring used in the car but as my car can charge up to 27.5a it would have to be at least 10 gauge(5.26mm2).
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a

gugusse
Posts: 19
Joined: Thu Jun 01, 2017 6:54 am
Delivery Date: 06 May 2017
Location: France

Re: I designed and built a 'better' granny charger ('11 leaf)

Mon Mar 19, 2018 2:40 am

Hello,

I did a bit the same thing last summer. I put the "controlboard" in a waterproof box and used some harting plug to be able to change the cords and the plugs.
Most of what I used comes from recycling old industrial part.

https://drive.google.com/file/d/16pI3i9 ... sp=sharing
https://drive.google.com/file/d/1a4t3TF ... sp=sharing

At the end, I bought 2 caps for harting plugs, the J1772 plug and the control board.
Max current is 25A because of the relay I used.

This is idiot proof too! When you change the plug, the EVSE will regulate according to the plug connected. A coding resistor in connected to the harting plug to limit the current.
For example (I'm in France, so 230V/400V) if I connect the regular house plug, It offers the the possibility to charge 8, 10 or 14A (with clear markings where to use what) via a little switch.

If I plug the small camping plug to the box, it will deliver 16A to the car.
If I plug the big camping plug to the box, it will deliver 25A to the car.
https://www.prozic.com/www2/media/P/1/P ... -26810.jpg

I have plugs for regular house plug, the 2 king camping plugs (16 and 32A) and 3 phases plugs (16 and 32A) because I have it at home and some friends too plus I work in the industry so even if I used only 1phase and neutral it is very usefull.

I will try to take more pictures to explain better.

May need to say that, I know what I do, I am certified for electrical work.

arnis
Posts: 835
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Re: I designed and built a 'better' granny charger ('11 leaf)

Tue Apr 10, 2018 2:11 am

Awesome and fancy. But I would rather have it "less fancy" and more awesome.
Put all electronics in a tiny watertight box near the plug. Have a button on the box
to switch between 10A, 13A and 16A. That box should be as big as cigarette pack.
And make it cheaper :D Also possible to make that cable 1.5mm2 (don't listen mericans,
they have fetish over massive AWG's :lol: ) as that cable in in open air. But it only matters
if there is any significant price drop or the cable diameter drops significantly (portable).
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

gugusse
Posts: 19
Joined: Thu Jun 01, 2017 6:54 am
Delivery Date: 06 May 2017
Location: France

Re: I designed and built a 'better' granny charger ('11 leaf)

Tue Apr 10, 2018 3:20 am


User avatar
EVDRIVER
Posts: 6232
Joined: Sat Apr 24, 2010 7:51 am

Re: I designed and built a 'better' granny charger ('11 leaf)

Tue Apr 10, 2018 7:21 am

If the relays are not at the mains side (not just the length) it defeats one of the main safety principals of the EVSE, to cut the power at the source side so there is no live power on the line to the car when charging stops or during other other events, there are other issues I can see that are pretty much a potential safety hazard as well. Just like any other safety device I suppose you can make it smaller and unsafe, like stripping the insulation off an extension cord and wrapping it with scotch take to save space. This unsafe design was already done and sold in the EU a long time ago and never sold here for that reason.
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