E-MotorWerks JuiceBox - an open source 15kW EVSE

[valerun]

Hi Guys,

Val here from Electric Motor Werks (http://www.emotorwerks.com/" onclick="window.open(this.href);return false;)

Just wanted to start a separate thread dedicated to questions & tech support for our JuiceBox product - a 15kW open source EVSE. As seen on KickStarter (http://www.kickstarter.com/projects/emw ... harging-st" onclick="window.open(this.href);return false;) and Engadget (http://www.engadget.com/2013/06/24/emw- ... g-station/" onclick="window.open(this.href);return false;). Since over 50 of our customers come from this forum, I wanted to make sure that we have a support thread here.

A quick refresher on the product: the DIY kits start at $149 and contain everything you need, including a 80A relay, a fully populated PCB, an industrial IP66 waterproof enclosure, chromed IP66 waterproof cable entry glands, nuts, bolts, and washers - even a decal! . Just add your cables (or get them as option from our shop). Premium versions include WiFi, color LCD, wireless remote, etc - all working out of the box.

~500 if these have been shipped and already help people charge their EVs faster than ever. Over half of these are charging Nissan Leafs.

Given this is a completely open source product, we would love to hear your suggestions / comments for the next version - check out specific details at http://emotorwerks.com/products/online- ... ng-station" onclick="window.open(this.href);return false; and let us know what you think!

Thanks,
Valery & Team JuiceBox.

PS. This is one of the latest of out products. Other products features in a number of publications (EAA, ChargedEV, Engadget, etc) include 12kW DC chargers, 25kW High-Voltage DC chargers, 20kW fully isolated EV chargers, and [soon] a CHAdeMO-compatible 20kW DC charger.

[ImpactVector]

I have one question on the current sensor you sell seperately. What else is needed to make that work?

Could one simple solder it on the board and adjust the firmware code?

Thanks
-J

[valerun]

I have one question on the current sensor you sell seperately. What else is needed to make that work?

Could one simple solder it on the board and adjust the firmware code?

Thanks
-J

Hi J - sorry for lag in response (still figuring out the subscription settings on MNL, it seems).

Nothing is needed - firmware already has all the code required. Also, all required components for signal processing are on board.

Valery.

[ImpactVector]

Aaah Victory!





Charged my Lead last night @ 7.2KW.

Only concern was the relay arm was 45 degrees warmer than ambient. I'm assuming that's ok?
Only issue was it took 2 seconds for me to work out why plugging my laptop into the USB port would stop the charger. After thinking about it I just used a header without the 5v Pin and was in business!

All in all I am very happy! Current Loop worked without touching the code.

Pwr: 7.2 KW
Time: 27.4 min
In: 3.2 KWH
238V, 30.3A
raw pV=2233,
calc pV=5903
E.M.W. 00:27
Thanks EMW!

[valerun]

super!

re relay temp - 45C over ambient is a bit high - we normally see 25-30C rise on 40A currents. pls double-check all high-current connections for screw tightness / surface contact etc.

Thanks,
Valery

[ImpactVector]

Valery,
I check tonight and the terminals are all 72 degrees (the box registers 55) but the copper arms on the relay register 84. Is that normal? All terminals are tight and I put copper washers under the lugs so that there isn't any question about contact.

Thanks
J

[valerun]

Valery,
I check tonight and the terminals are all 72 degrees (the box registers 55) but the copper arms on the relay register 84. Is that normal? All terminals are tight and I put copper washers under the lugs so that there isn't any question about contact.

Thanks
J

hm. what about crimps? can you measure their temp up close?

[ImpactVector]

Valery,
I check tonight and the terminals are all 72 degrees (the box registers 55) but the copper arms on the relay register 84. Is that normal? All terminals are tight and I put copper washers under the lugs so that there isn't any question about contact.

Thanks
J

hm. what about crimps? can you measure their temp up close?

The crimps on my cable connections are lower. They are around 60. It's just the contactor arms.

Another odd thing I am seeing ( it's a mod. Not the base product) is my juicebox appears to lose connection to my i2c rtc when the relay opens. Have you seen that before? As soon as I disconnect the car it goes back to showing the normal time.

Thanks again!
-j

[valerun]

these temps are a bit higher than what we see in our units here but not high enough yet to be a real issue. I would watch them periodically, though. Another cool mod to do would be to fit a thermister on the board and do some kind of derating of the pilot when the temp is higher than 85C in the box (e.g., in the summer, under the sun, etc).

Re i2c: this is most likely noise from the relay's inductive kickback. We do have an antikickback diode and capacitor fitted in but looks like we could use more filtering. one thing you could try is a 1 ohm resistor in series with the 5V supply line from the power supply to the PCB. Another is to increase the 5V supply filtering capacitance from 50uF now (C3) to something like 1000uF.

Let us know how it works. Also, would it be possible for you to share the i2c RTC code you have added?

Thanks,
Valery

[Levi8than]

Charged my Lead last night @ 7.2KW.

I'll bet the current is right, but the voltage was sampled prior to the the car pulling any load.
If you are comfortable with AC mains, stick your multi-meter across the relay while current is being pulled by the car and see what AC voltage you get.
I'll bet your line is drooping to around 218 volts. If so, this makes more sense.

If not, maybe there's some process variation in the leaf chargers and the blanket 6.6 kw is more of an average or lower bound. Not sure. But congrats, you got a faster on-board charger than I did.