Build you own Charging Station for about $375

If you are interested in building your own portable EVSE (charging station) here are some instructions and pictures of how to do it. This unit is partially assembled when you get it and you need some basic soldering skills and a couple of hours along with some hand tools. The box, the relay, the circuit board, a small power supply and colored wire needed come in the kit for $150 (Electric Motor Werks http://www.emotorwerks.com/products/online-store/product/show/44-emw-juicebox-an-open-source-level-2-15kw-ev-charging-station). The output cable and J1772, that plugs in the your electric car, is $190 and 240 volt input cable and plug attached is $25 at Home Depot or use the cable and plug of your liking. You can buy it fully assembled if you like for $407 but, what’s the fun in that? This is not an ad for the company that makes the kit and I have no relationship or interest in EMW, I just enjoyed putting the EVSE together. The following are my instructions of how I assembled my EVSE.
Download and print the 2 photos for reference :
http://www.flickr.com/photos/45428304@N05/11074309225/
http://www.flickr.com/photos/45428304@N05/11261270554/



1. Make 5 lengths of blue wire 1 1/2 inches long, strip both ends.

2. Solder one end of each of these wires to the five holes starting at the top left side on the circuit board, four on the J3 & one on the J2 position (bottom end of the circuit board, for these instructions, has “JuiceBox” print on it).

3. Make 2 lengths of red wire, one 5 inches, the other 8 inches, strip both ends. Attach a ring style wire end blade connector to one end of each.

4. Attach the other ends of each of the red wires to the, lower, first two screw positions of the power supply, then twist the two red wires together for the first 3 inches.

5. Connect the free ends of each the blue wires to the top 5 screw positions of the power supply, one position is left empty.

6. Carefully move the circuit board, now connected to the power supply, into the box.

7. Screw the circuit board to the box with the white spacers between and tighten to where washer flattens slightly on the outside of the box.

8. Position the power supply and similarly screw it to the box.

9. Make 2 lengths of yellow wire, one 1 1/2 inches, the other 6 inches, strip both ends. Attach a ring style wire end blade connector to one end of each.

10. Insert the yellow wires into the two upper holes of the J1 connector by gently pushing down to open each of the positions, then inserting the wire and releasing. Twist the two yellow wires together for the first one inch.

11. Make 2 lengths of black wire, one 2 inches, the other 6 inches, strip both ends. Attach a ring style wire end blade connector to one end of each.

12. Insert the black wires into the two lower holes of the J1 connector by gently pushing down to open each of the positions, then inserting the wire and releasing.

13. Make two wires, one blue and the other yellow, about 3 inches long, strip both ends. Attach a ring style wire end blade connector to one end of yellow wire.

14. Solder the blue wire to the pilot hole in the circuit board, bottom left side, marked “pilot”.

15. Solder the yellow wire to the ground hole on the circuit board just to the right of the pilot hole.

16. Unscrew the clear cover on the relay and discard the cover.

17. The two relay contact points will be closest to the power supply. Screw the relay in the box with the relay contact points closest to the power supply. Input side is on the lower end and output side on the upper end of the relay. Tighten the 4 nuts to where washer flattens slightly on the outside of the box.

18. Strip 4 inches of the outer jacket of the input cable making sure not to cut into the insulation of the inner wires. Cut off all the white filament material and cut the white wire off about and inch from where you removed the outer jacket. Tape over the end of the white neutral wire, it is not used here.

19. Shorten the green wire making it one inch shorter than the black and red wires. Strip a 1/2 inch of insulation from the ends of all three input wires. Cut one inch pieces of heat shrink insulation for each of the wires and slide it on and tape them in place so it won’t fall off while you are crimping the lugs on. If you don’t have a crimping tool use a metal bench vice to tightly secure the three connector lugs or a very strong set of pliers. Make sure the connectors are all in a similar plain so the wires don’t need to be twisted the connect to the relay. Slide the heat shrink insulation over the connection points and heat shrink them in place.

20 Tighten the nuts on the large input and output glands against one another at the bottom end of the box (not the outer sealing nuts) .

21. Put a 1 inch long bolt through the ground hole (just below the relay ) and tighten the nut to where washer flattens slightly on the outside of the box.

22. Push the input cable through the left input gland at the bottom end the box and connect the black input wire to one side and the red input wire to the other side of the input on the relay. Place one of the red wires from the power supply on top of each input wire connectors before tightly securing the screws to the relay contacts

23. Place the green input wire connector on to the ground post along with the yellow ground wire from the circuit board and secure them loosely (the yellow/green wire of the J1772 cable will also connect to this post).

24. Make sure you have 8 inches of the outer jacket removed from the J1772 cable making sure not to cut into the insulation of the inner wires. Cut 2 inches off the red wire and strip a 1/2 inch of insulation from end of all wires of this cable. Push the group of wires through the output cable gland.

25. Push the black and red wires through the GFCI coil, keeping then parallel to one another (later use silicone sealant to keep the wires in position). Slide a 1 inch piece of heat shrink insulation on each of the wires and crimp on the connector lugs. Cover the shrink insulation over the connection point of the two wires and heat shrink. Connect the large red output wire to the inside relay connection, placing one of the yellow wires from the J1 position of the circuit board on top and securing both tightly to the relay. Do the same for the large black output wire on the other side of the relay along with the other yellow wire (on top also) from the J1 position, securing both tightly to the relay. Bend the lug 90 degree up to allow the black to meet the relay connection.

26. Slip on a piece of shrink insulation on yellow/green wire and crimp on the connector lug and shrink insulate it and then connect it to the ground post tightly. (post will have the green input, the yellow circuit board ground and yellow/green output wires on it).

27 Place an inch piece of small shrink insulation on the green pilot wire in the J1172 cable and solder it to the blue pilot wire from the circuit board and heat shrink insulation over the connection.

28. Tighten both input and output gland nuts on the box so there is no movement of the power cables and the openings are sealed tight.

29. After you check all your connections your EVSE is complete and is ready for testing.

Could you post the manufacturer and part number for the 40A relay/contactor? A picture of the nameplate would also be nice.

srl99 said:

Could you post the manufacturer and part number for the 40A relay/contactor? A picture of the nameplate would also be nice.

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It's actually rated 80A. You can get the spec sheet for it here. I just bought one for $20 from amazon and intend to try it out in my open EVSE.

I think the 2nd pic you linked to is a little misleading. If your input cable is a standard 50A range cord like this one you should be attaching the black and red (hot) wires to the relay and leaving the white (neutral) unused. I don't know why EMW shows a pic with the white wire connected and red chopped off. EDIT: I guess that was your pic and not EMW's - EMW does show a pic with a white wire attached to the relay, but that's because they use a 3-wire cable that doesn't have a red.

Same relay for less. The spec. sheet says 100 milliohm contact resistance, that is 160 watts at 40 amp and 640 watts at 80 amps. Figures they would use a relay that cost them less the $5. A SquareD 75 amp relay costs $100.

http://www.aliexpress.com/item/JQX-62F-2Z-80A-DPDT-DC-12V-Coil-Electromagnetic-Power-Relay/468483981.html

pchilds said:

Same relay for less. Let me know how hot it gets at 40 amps.

http://www.aliexpress.com/item/JQX-62F-2Z-80A-DPDT-DC-12V-Coil-Electromagnetic-Power-Relay/468483981.html

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I think I'd like to try that one out for that price in my OpenEVSE and my Clipper Creek. Maybe even my future 40 amp portable EVSE.

Read my edited post above. :shock:

In reply for Fooljoe’s comment, about the red wire no being used in the input cable. This EVSE has a 14-50P input cable connected to it. I have two adapters, a 6-50P (Leviton three 3 pin) to 14-50R (four pin) and a 10-30P (old electric dryer three pin) to 14-50R (four pin) both of which use the ground contact as the neutral. Were the red hot contact wire used the EVSE would not receive 220 volts power.

sobayimage said:

... and a 10-30P (old electric dryer three pin) to 14-50R (four pin) both of which use the ground contact as the neutral. Were the red hot contact wire used the EVSE would not receive 220 volts power.

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You don't need a neutral at all with 240 volts in the USA/Canada.

The reason the "14" series NEMA plugs have a neutral is for 120 volt appliances and components in 240 volt appliances. For instance, a 240 volt dryer uses 120 volts in the control panel. A motor home or travel travel rarely uses 240 volts at all, but both 120 and 240 volts is available with a properly wired NEMA 14-50.

None of these are situations for our 240 volt EVSE's. I recommend NOT using ground as a neutral; again, it's not needed. Leave ground for the job it was intended for. I usually leave the neutral pin completely out; it's easier to plug in with only three pins, plus it can also be plugged into any amperage 14 series plug. Obviously, due diligence must be used to not overload a dryer NEMA 14-30 plug with 40 amp Rav4 EV use.

sobayimage said:

In reply for Fooljoe’s comment, about the red wire no being used in the input cable. This EVSE has a 14-50P input cable connected to it. I have two adapters, a 6-50P (Leviton three 3 pin) to 14-50R (four pin) and a 10-30P (old electric dryer three pin) to 14-50R (four pin) both of which use the ground contact as the neutral.

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"Use the ground contact as the neutral" in what sense? A 6-50 has hot-hot-ground, a 10-30 has hot-hot-neutral, and a 14-50 has hot-hot-neutral-ground. For both adapters you should connect hots to hots (usually labeled x and y.) For the 6-50 you should connect ground to ground, and for the 10-30 you should connect its neutral (only because it doesn't have a ground) to the 14-50's ground. In both cases the 14-50's neutral should be unused.

sobayimage said:

Were the red hot contact wire used the EVSE would not receive 220 volts power.

Click to expand...

This is incorrect. If the red wire is actually a hot (and it will be unless your adapters are wired incorrectly or you've got a strange/miswired input cable), then the only way to get 240v power is to connect both black and red to the relay.

With residential split-phase 240v service, 240v is available from hot to hot, which are usually black or red wires. Either hot to neutral (usually white) gives 120v. With the input cable wired as pictured your EVSE will work, but you'll be charging on 120v. Have you actually tried it?

I looked again at the picture on EMW's site, and I see that they're using a 3-wire cable, so presumably they leave the neutral blade of the 14-50p unused and connect black and white to the hot blades (and so to the relay.) But if you're using a 4-wire cable then you should definitely be connecting black and red to the relay and leaving white unused.

I used the wrong color of wire though it was connected to the right post on the hot side of the input plug. I have now reconfigured the plug and am using a red wire as a hot in place of the white wire and the white neutral wire is not connected to anything.
I have tested the unit using 120 volts and 240 volts inputs and it works seamlessly. This EVSE works from 15 to 40 amps output with just a turn of the variable resistor when using 240 volts. I got a carrying bag from Harbor Freight Tools for $20 and the unit and cables fit just perfectly making it very portable.

Sounds like it's working out nicely. For the variable output, is it continuously adjustable or just for the previously mentioned settings? Also have you tested how hot it gets at 40 amps? There was some talk in the openEVSE thread over in the Leaf forum that the relay EMW uses can run too hot and possibly need ventilation.

I checked the temperature of the relay after two hours of charging at 40 amps with a non-contact laser temperature meter and it was 90 degrees with the cover was off the EVSE. Some of the heat may have dissipated to the room that was 55 degrees at the time. The orange variable input resistor in the center of the circuit board tells the car what amperage is available from the EVSE. The resistor can be rotated 180 degrees, so 15 amps is 45 degrees from left, 30 amps is 90 degrees straight up and 40 amps is 120 degrees to the right. It may be a little crude but works just the same.

But are those 15/30/40 settings the only ones available or can you set it to pretty much anything in between?

Good question about current limit adjustment. The resistor has a linier adjustment and can be rotated 180 degrees (0 amps full left and 60 amps full right). Please see this photo showing how and where to change the current available message that the EVSE sends to the car.

http://www.flickr.com/photos/45428304@N05/11280429546/in/photostream/

Thanks for the close-up pic, but I'm still not sure what the answer is. So can you set it to 24 amps, for example, by setting it in between 45 and 90 deg (I guess with a little trial and error and an ammeter) or does it only "snap in" in a few predefined settings?

fooljoe said:

Thanks for the close-up pic, but I'm still not sure what the answer is. So can you set it to 24 amps, for example, by setting it in between 45 and 90 deg (I guess with a little trial and error and an ammeter) or does it only "snap in" in a few predefined settings?

Click to expand...

In my limited experience with that type of trim-pot, it does not have any detents and also is not particularly smooth in operation. It is also not designed for repeated use, but rather trimming (tuning) a circuit to the proper operating value and left alone. However, I'm not an EE and don't deal with these regularly, so I may be way off base.

Things in this world are rarely exact. To get close to 24 amps with this configuration of EVSE is to turn the resistor to exactly between 45 degrees and 90 degrees of rotation and it should give you exactly 22.5 amps - is that good enough?

Ok, so you can set it to pretty much anything, it's just difficult to know what exactly you're setting it to, right? I guess that's decent enough for a fixed EVSE, since you can probably get it right where you want with some trial-and-error. Although it'd be pretty annoying for use on the road, where you might want to easily switch between 12, 16 (e.g. using a quick220 at a friend's house), 24 (dryer outlet), and 40 amps (RV parks) and possibly vary it further (bump it down a bit if you need to share a circuit, for example.)

I'd still take an open-EVSE instead primarily for the simple adjustability with a pushbutton and LCD display, and for the additional flexibility in selecting vital parts like the relay. But that flexibility does come with a convenience penalty, as there's no ready-to-go kit like there is for the Juicebox - you've got to do a little homework (or just buy one pre-made from an experienced builder like I did.) Maybe the "premium" edition of the Juicebox addresses some of these concerns (for an extra $110.)

Hi Guys -

Valery from EMotorWerks here. Very happy to see you guys using our products! We have just started a separate thread on this forum for JuiceBox questions / support - please feel free to post any questions there: http://www.myrav4ev.com/forum/viewtopic.php?f=7&t=893

We would also LOVE to hear your feedback like the points you raised above. Such as ability to get confirmation of your current setting etc. This product is in constant development and we depend on you to give us your ideas.

For example, we have received a number of requests for indication of charging status. However, it's surprisingly expensive to put in waterproof visual indication and we just don't have that kind of room in our BOM for Base Edition. So we have decided to add audio indication in the next release (coming in January!). Now that I saw the feedback above, we will probably use those for current setting confirmation, as well. And, of course, in Premium Edition, all the settings are echoed on the LCD.

For some recent updates on the project, etc, see our KS page at http://www.kickstarter.com/projects/emw/emw-juicebox-an-open-source-level-2-ev-charging-st.

~500 of these have been ordered so far, with ~300 of them already operational. Some comments: http://www.emotorwerks.com/component/content/article/78-emw/160-juicebox-testimonials.

Let us know what we can do better!

Thanks,
Valery