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Discussion Starter · #1 · (Edited)
Just wanted to tell you all that you do have an option other than buying an EVSE: Build one!

I used the OpenEVSE platform to build this 70A (yes that's 70 AMPS) EVSE!
Note that the EVSE is currently configured for 30A since I could not find 80A fuses that would fit inside my enclosure, and I am currently using a NEMA 14-50 receptacle (50 Amp max).

Parts list:
-OpenEVSE board: $80 + $5 shipping (http://code.google.com/p/open-evse/)
-240VAC to 12VDC PSU: sourced from extra parts at home
-70A J1772 connector with 8m cord: $250 + $30 shipping (http://www.tucsonev.com/index.html)
-NEMA 4X Enclosure: $70 incl. shipping (http://www.ebay.com)
-2x 100A Fotek Solid State Relay (SSR): $20 incl. shipping (http://www.ebay.com)
-2x CPU Heatsinks: sourced from old PCs
-Heatsink Compound: sourced from machine shop
-Adafruit RGB LCD: $25 + $7 shipping (http://www.adafruit.com/products/714)
-Standoffs/Nylon Nuts/Nylon Washers: $5 (Local Electronics shop)
-3ft 8AWG MGT (450C) Nickel-plated stranded copper wire: $10 + $5 shipping (Plastic Process Equipment)
-DIN Rail and Fuse blocks: sourced from machine shop
-Low head socket cap screws: $10 + shipping (McMaster Carr)
-Nylon-insert lock nuts: $5 (McMaster Carr)
-Buna Cord Stock: $3 + shipping (McMaster Carr)
-O-rings for screws: sourced from machine shop
-1/4" Scratch-Resistant Polycarbonate: $10 + shipping (McMaster Carr)
-Shipping from McMaster: $10

Total Cost: $545 (I estimate the DIN rail and fuse block/fuses would cost an additional $100)

I enlisted the help of my good (older) friend who works in an injection molding shop to help with this project.

P.S. Sorry about the HUGE photos... Tried to resize but that didn't work

First, we needed to lay out all the components, where we would need to cut the hole for the LCD, screws, etc.





SSRs and Heatsinks:


8AWG MGT (Very high temp) Wire:

This was used because anything larger than 8AWG would not fit in the SSRs' terminals!

Technical Drawing of Polycarbonate:

Note that we only ended up using the outer channel as we felt it would be more than sufficient in keeping water out.

Practice piece and layout on finished piece:



Next, we needed to cut the Polycarbonate and put the channel in for the o-ring and screws

Cut piece of PC on the turntable in the milling machine:


Cutting the channel for the o-ring (cord stock):



Sinking the holes for the low-head socket cap screws:






Finished Polycarbonate Cover:


PC Cover in place with cut holes in the NEMA 4X Enclosure:


LCD mounted on the panel, with cover and one heatsink in place:


Cleaned up the enclosure, ready to mount everything:


You can see the two holes on the side (bottom) for the strain reliefs/cable glands:


OpenEVSE, AdaFruit LCD, and fuse block mounted on the panel:



Everything wired up and ready to go:




EVSE Working:



That's it!
I realize there are steps missing but those are all the pictures I have.

Here's to doing it yourself! (and saving large sums of money in the process)

Future upgrades:
-Possibly upgrade to 50A (KTK-50) fuses
-Find a 70A receptacle?
-Would really love some kellems grips but they are rather expensive!

Comments, suggestions, and thoughts are greatly appreciated!
 

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Cool.

For those who want to convert an existing wired system to portable, where did you get the threaded lock nut fittings that attach the cord to the box?
 

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Discussion Starter · #3 ·
Cool.

For those who want to convert an existing wired system to portable, where did you get the threaded lock nut fittings that attach the cord to the box?
I got that from a local electrical supply shop.
However, I know that Grainger and McMaster stock those fittings.
I recommend going with SOOW or SJOW cord since they're waterproof. A neoprene jacket insulation with a 90C rating is preferred!
 

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Very nice set of pictures !
What again was the part Under the heatsink ?

haha I guess the relays - the pics took a while to load the whole set.
 

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This is [email protected]$$!!!

Nice work! A suggestion would be to put the pics into a PDF doc along with notes and a parts list. This would help other DIYers and solve your large picture issue ;)

I currently have 2 EVSEs, a 30A and a 32A. As it stands I'll be happy when I have 2 EVs that can make the most of those capabilities! 70A will be insane! At current charge rates that will generate 40+ miles per hour! Sick
 

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Nice job and I appreciate the bill of material list and pics. I did save this thread as a link for reference.
 

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Discussion Starter · #9 · (Edited)
Very nice set of pictures !
What again was the part Under the heatsink ?

haha I guess the relays - the pics took a while to load the whole set.
Yep, those are the SSRs. They throw a bit of heat, even at 15A (which is what the volt uses)
I actually used Arctic Silver 5 for heatsink compound. It's more expensive, but has superior heat transfer.

This is [email protected]$$!!!

Nice work! A suggestion would be to put the pics into a PDF doc along with notes and a parts list. This would help other DIYers and solve your large picture issue ;)

I currently have 2 EVSEs, a 30A and a 32A. As it stands I'll be happy when I have 2 EVs that can make the most of those capabilities! 70A will be insane! At current charge rates that will generate 40+ miles per hour! Sick
I might work on a PDF which would be nice... though I need to find a good (free) editor.

70A WILL be insane. I wanted to future-proof this as much as possible. The J1772 spec calls for a max of 75A I believe.

Maybe I'll use some 4AWG welding cable and some Anderson connectors, and then simply swap out the 14-50 plug and connect it directly to the AC mains without a receptacle (the female or male end will be on the AC side)

Nice job and I appreciate the bill of material list and pics. I did save this thread as a link for reference.
Thanks! I added one more thing to the material list, the 12v PSU. I got that from the spare parts I had lying around at the house. It's just your average 100-240V 50-60Hz switching PSU.

I understand the wanting to make it yourself. I don't know if I would have attempted this, but that's a pretty good write up. Thanks! You should submit that to MAKE magazine.
You're welcome. Maybe I should submit this to MAKE magazine.
The hardest part was cutting the Polycarbonate cover, since we had to cut a non-square channel for the o-ring, and use two drill bits for each of the holes so that the screws would sit inside the PC cover. This took us about 2-3 hours.

Cutting the NEMA enclosure and the holes for the cable fittings was easy, it only took about an hour on the milling machine.

By far the longest amount of time was spent figuring/laying things out!
 

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OP: Very nice! I rebuilt my 240V Voltec using the OpenEVSE when it started flaking out due to heat problems; pretty easy to do, and worked first time. Very happy with OpenEVSE.

BTW, I didn't think SSRs were recommended for this application (look under the "Details->The bad" section):
http://code.google.com/p/open-evse/wiki/EVSE_EV_ChargeAmerica_Upgrade
 

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Discussion Starter · #13 ·
This is great information can you show the completed schematic?
Tom
I'll Try to find it. I have it somewhere.

As a side note, Leviton is now selling (as of late August I believe) a 30 amp J1772 plug and cord for $126 shipped which is also an option for DIYers. This is a huge price breakthrough for what should be high quality.
http://store.leviton.com/J1772-Charge-Connector-and-Cable-Electric-Vehicle/b/5742800011
Cool! I knew that these things couldn't cost nearly as much as they sold for. I think the majority of the cost is in the J1772 connector.

OP: Very nice! I rebuilt my 240V Voltec using the OpenEVSE when it started flaking out due to heat problems; pretty easy to do, and worked first time. Very happy with OpenEVSE.

BTW, I didn't think SSRs were recommended for this application (look under the "Details->The bad" section):
http://code.google.com/p/open-evse/wiki/EVSE_EV_ChargeAmerica_Upgrade
Yep, Chris Howell has done a phenomenal job with his OpenEVSE. The footprint of the EVSE board has to be seen to be believed!
If you had a small enough contactor, you could probably fit an entire 30 amp EVSE in a 4"x4" Junction Box!

As for the SSRs, I think it's more of a personal preference over them actually being a bad choice.
Many people have experience with them in heaters, where they fail often.
However, in this application I expect them to be far more reliable than a contactor.
Plus, I can switch the current to the car using the 12V supplied by the OpenEVSE without using a control relay, which eliminates another possible point of failure. It also gave me an excuse to use heatsinks, which make the whole thing look far more [email protected]$$
 

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You can export to .pdf from open or libre office, both are free, and reasonably easy to use. You have your heatsinks turned sideways FWIW, for best heat dissipation (assuming you're wall mounting this), and this error more than overwhelms any superior heatsink grease you might have used. Convection is an up/down thing, not a side to side thing - you'd need fans for that. And yes SS relays do make some heat, as they have a bit of voltage drop - much more than mechanical relays.

No, I'm not saying this isn't a great thing! My own setup is somewhat custom as well...and I put my SSR's on a big vertically oriented heatsink myself. Even with the extra couple volt drop (the biggest loss in the system), they are so much more reliable than the mechanical ones, it seems way worth it. Even with no arcing on the mech relay contacts, they do fail in some million or so closures (if they are top notch, it's not uncommon to see them fail in the mere thousands).

Note, the Volt ramps up its load very gracefully, so even mech relays *might* be reliable unless you are hot-unplugging and contacts don't make/break in the right order. Else even they will never see an arc across the contacts.
 

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Discussion Starter · #15 ·
You can export to .pdf from open or libre office, both are free, and reasonably easy to use. You have your heatsinks turned sideways FWIW, for best heat dissipation (assuming you're wall mounting this), and this error more than overwhelms any superior heatsink grease you might have used. Convection is an up/down thing, not a side to side thing - you'd need fans for that. And yes SS relays do make some heat, as they have a bit of voltage drop - much more than mechanical relays.

No, I'm not saying this isn't a great thing! My own setup is somewhat custom as well...and I put my SSR's on a big vertically oriented heatsink myself. Even with the extra couple volt drop (the biggest loss in the system), they are so much more reliable than the mechanical ones, it seems way worth it. Even with no arcing on the mech relay contacts, they do fail in some million or so closures (if they are top notch, it's not uncommon to see them fail in the mere thousands).

Note, the Volt ramps up its load very gracefully, so even mech relays *might* be reliable unless you are hot-unplugging and contacts don't make/break in the right order. Else even they will never see an arc across the contacts.
I actually am leaving this on the floor, which is why I mounted them "sideways." I also left about an inch or two between the heatsink and the back of the box, so that if I do eve decide to wall-mount, there will be enough airflow to cool the SSRs. Note that this will always be placed outdoors as I do not have a garage.

I actually measured the voltage drop across the SSRs to be 1Vrms. At 15A (which is what the Volt draws), that's a 1/15 ohm resistance (V/I=R), and the power dissipated is 15 watts (P=VI or P=(I^2)*R).
15 watts is minimal since those heatsinks were designed to dissipate about 150W from CPUs (albeit with a fan).
(This problem reminds me of high school physics... haha)

It was breezy last night when I was charging my Volt, and the heatsinks were only very slightly above the ambient temperature. So again, I'm not really worried about heat dissipation.

As for the .PDF, I do remember openoffice having that functionality... I'll go ahead and give it a shot later today.

And yes, I do expect the SSRs to be very reliable, and I always unplug the car-side first before the hot-side if I ever need to move the EVSE, so I expect this setup to last a VERY long time!
 

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Bumping, because this really was a good DIY example and...

As a side note, Leviton is now selling (as of late August I believe) a 30 amp J1772 plug and cord for $126 shipped which is also an option for DIYers. This is a huge price breakthrough for what should be high quality.
http://store.leviton.com/J1772-Charge-Connector-and-Cable-Electric-Vehicle/b/5742800011
...if money is paramount, I see no reason OpenEVSE can't get done for <$300. I count $279 as possible for 30A units, between:
-30A relay $13
-12V power supply $45
-Current Transformer (Donut) $11
-OpenEVSE, J1772 compliant, Chris Howell board $85
-Leviton 30A 8meter plug $126
-10ga 240v Dryer dongle, $15 Home Depot

$279 is your basic total, assuming you have ~20 gauge wire, a box, solder, a volt tester, and simple electrical tools. A 30A fuse is a good idea, but at least one manufacturer on GM-Volt doesn't include internal fusing (I wired one inline). I also used a $5 ground bar, though solder/tape/a really big screw cap would probably do the trick. A higher watt solder gun (~100w) is recomended, if you're going to try heating up 10 gauge wire, but in the end the job is surprisingly straight forward. I was going to include this in my own write-up (w/pics). Faith in executing this relatively simple schematic is where confidence begins:

http://open-evse.googlecode.com/files/EVSEwAdvanced_Power_supply.pdf

There are vitues to OpenEVSE that other options do not provide, like swapping failed parts instead of wholesale replacement, or the idea that I believe uprating the relay amperage may be all that is required for future, higher charge rate EV's. Otherwise, getting the chance to build another one actually sounds fun. What I noticed about the 70A plugs was the use of 6 gauge wire, vs 10 gauge in Leviton's 30A unit. I don't know what SPX uses, but they're to be fused at 20A, and still charge a Volt in ~4hrs. The OE charge cord is something like (14ga?/120v).

Anyone care to guess the gauge of Tesla's new Supercharger? It looks like the girth of a fuel hose, and it "pumps" a coffee-spitting 90kw:http://futuristicnews.com/vast-network-of-supercharger-stations-for-model-s-electric-car/
 

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I don't know what SPX uses, but they're to be fused at 20A, and still charge a Volt in ~4hrs. The OE charge cord is something like (14ga?/120v).

Anyone care to guess the gauge of Tesla's new Supercharger? It looks like the girth of a fuel hose, and it "pumps" a coffee-spitting 90kw:http://futuristicnews.com/vast-network-of-supercharger-stations-for-model-s-electric-car/
The OE cord is using 14AWG wire. I would guess that the SPX units are also 14AWG wire as 14AWG can be used up to 16A continuous (20A circuit).

If I had to guess for the Tesla Supercharger that would probably be 90KW @ 500VDC would be 180A. For that you would need a 3/0 (000AWG) wire minimum. That would be a heavy and large cord.
 

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PJwood, when are you going to be able to post pics of your EVSE? I am in agreement with you.
 
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