E-MotorWerks JuiceBox - an open source 15kW EVSE

[valerun]

Old vers: V8.7.9 08:55 (2)
New ver: V8.9.1 08:55 (2,55) ; where the last two digits indicate an internal JB temperature of 55C, (or 131F).

As a side note, the way the new temperature management feature works, if an OTP (over temperature protection) condition occurs, when the internal temperature of the Arudino microcontroller exceeds 90C, the JB will suspend active charging for at least 10 minutes, thus preventing overheating. Conversely, if the temperature drops below -20C, a 6W heater energizes to try to keep the JB above freezing. Above -10C, the heater turns off.

To best of my knowledge, no other EVSE has implemented these feature!

Valery, is this correct?

Very observant... Yes, this is how it works. The feature is not fully precise yet hence the upper limit on temperature is so high (90C). In V8.9.2, we will have auto-calibration code that will calibrate the temp reading to room temp at first run and store that constant in EEPROM for life of the unit.

 

[dsinned]

I just successfully modified my JBB firmware (originally V8.7.9) to add in the new V8.9.1 code for monitoring the Arduino MCU's internal temperature and reporting it on the display module. I count 20 characters for all the info reported on the first line of the 160x128 uOLED in landscape mode. The temperature reported after about 90 minutes of warmup time, while actively charging my RAV4 at ~7.5kW was ~50C (122F). The ambient air temp inside my garage, with the JB mounted on a wall, was ~80F. This is a very reasonable delta-T for the ATMEL ATmega328 MCU with an 85C maximum operating temperature rating.

 

[valerun]

I just successfully modified my JBB firmware (originally V8.7.9) to add in the new V8.9.1 code for monitoring the Arduino MCU's internal temperature and reporting it on the display module. I count 20 characters for all the info reported on the first line of the 160x128 uOLED in landscape mode. The temperature reported after about 90 minutes of warmup time, while actively charging my RAV4 at ~7.5kW was ~50C (122F). The ambient air temp inside my garage, with the JB mounted on a wall, was ~80F. This is a very reasonable delta-T for the ATMEL ATmega328 MCU with an 85C maximum operating temperature rating.

Thanks for your report! But why just 7.5kW for RAV4? ;-))

 

[dsinned]

Good question . . . I don't think I have sufficient size copper wiring to support a full 40+ amps. No problem at 32A, however.

I believe the dedicated wiring to the NEMA 14-50R outlet in my garage is only 10AWG. I need to recheck this to be sure. It might be 8AWG, but I'm not positive because I cannot see any "AWG" marking on the insulation. The circuit breaker rating for this outlet just happens to be 40A as well, which was being used for a hot tub in my backyard. I disconnected the hot tub and had it removed from the property about two years ago. (Then, I relocated this dedicated 240V circuit to the garage after I got my RAV4 EV and a Leviton 32A L2 EVSE).

The rerouted wiring from the AC mains service panel to the garage outlet goes thru a conduit in the crawl space under the house over a distance of ~30 feet. The rest of the wiring from the AC outlet to the JB (via a 6' input cable) and to the J1772 plug, is all 8AWG. The accessible wiring from end to end covers an additional distance of approxiately 30 feet.

For testing purposes, I have charged my RAV4 at 40A for relatively short periods of time. This was just to make sure the JB could handle a full load while charging my RAV4 EV at 10kW, which it did just fine. There was no overheating in any portion of the input/output AC cabling or at the J1772 charge port connector plugged in to the car. The cable was warm to the touch, but far from overheating. Of course, I adjusted the JB current limit to just below 40 amps to prevent tripping the breaker.

I usually only do scheduled charging of my EVs after midnight while i'm sleeping and don't want to risk any possibility of overheating my household wiring, so I limit the JB to only 32A to play it safe. If it turns out I have all 8AWG wiring, even the 30' run under the house, I will upgrade the breaker in the panel to 45A, so I can fast(er) charge my RAV4 from my JB. :mrgreen:

 

[dsinned]

Valery, what's the status of providing the new V8.9 features, that were added in to the latest firmware (i.e. temp monitoring/reporting and more accurate AC voltage measurement), in older V8.7.x firmware? Please advise. Thanks.

 

[valerun]

Valery, what's the status of providing the new V8.9 features, that were added in to the latest firmware (i.e. temp monitoring/reporting and more accurate AC voltage measurement), in older V8.7.x firmware? Please advise. Thanks.

dsinned - do you think you can come over to the shop sometime next week? we can sort it out then

let us know

V

 

[dsinned]

Sure, I would be happy to come over. When would be a good time for you? Do want me to bring my JB with me?

Btw, in case you may have forgot, I have already successfully modified my V8.7.x firmware to include the new temperature monitoring features. I took a look at the other code changes in V8.9.1 firmware, but could not quite understand how to implement any of the other changes. I am NOT a programmer! I also modified my hardware to upgrade the LCD to a slightly larger, but fully interchangeable 4D OLED 1.7" display. The nice thing about that upgrade is the new OLED has a built in screen saver and 20 characters fit on each line.

 

[valerun]

Sure, I would be happy to come over. When would be a good time for you? Do want me to bring my JB with me?

Btw, in case you may have forgot, I have already successfully modified my V8.7.x firmware to include the new temperature monitoring features. I took a look at the other code changes in V8.9.1 firmware, but could not quite understand how to implement any of the other changes. I am NOT a programmer! I also modified my hardware to upgrade the LCD to a slightly larger, but fully interchangeable 4D OLED 1.7" display. The nice thing about that upgrade is the new OLED has a built in screen saver and 20 characters fit on each line.

You around this weekend? Afternoons on any day should work. Just let us know a few hours in advance so we are sure top be there.

Thx!

V

 

[dsinned]

How about later this afternoon. Say around 3:30pm?

 

[valerun]

How about later this afternoon. Say around 3:30pm?

good. see you then. bring your unit and your firmware

 

[dsinned]

Okay, see you soon. Leaving SJ at 2:30, so I should be able to get there by 3:15pm.

 

[dsinned]

The JuiceBox ROCKS!!!

Just want to say thanks and express my appreciation to Valery and the staff at eMotorWerks for all the great support and their personal assistance!

 

[valerun]

The JuiceBox ROCKS!!!

Just want to say thanks and express my appreciation to Valery and the staff at eMotorWerks for all the great support and their personal assistance!

Thanks dsinned!

in other related news (also on insideevs.com today):
-------
How will YOUR EVSE hold up to the beating of the harsh California weather?! ;-)) EMotorWerks is launching the EVSE Ice Bucket Challenge!
https://www.youtube.com/watch?v=7OBEMHkMzII" onclick="window.open(this.href);return false;
JuiceBox now challenges Schneider and Bosch EVSEs!
---------

enjoy ;-))

V

 

[dsinned]

The JuiceBox EVSE "Ice Bucket Challenge" demonstration was AMAZING!!!

I'd bet there are still some other company's EVSEs that would not be up to the same test!

CONGRATS!!!

 

[bkinsl]

Hi there, wondering if anyone has measured the power consumption of the JB premium while in standby? The logs are great on the stats website, but only shows consumption during charging cycles. Hoping to understand amount of lifetime JB usage including idle standby time.

Also, a newbie question on charging the Leaf with a 6.6 kWh charger upgrade. Can the leaf accept more than 28A from the JB or is that the max if the box is putting out 6.6 kWh?

Thanks!

 

[dsinned]

Valery is the real EXPERT here, but I think the standby consumption should be almost insignificant; probably not more than 1 to 2 Watts maximum. Even in fully "active" mode, the low power CMOS 8bit microcontroller only draws 1 Watt (absolute max. rating); Atmel's spec says, 0.75uA in Power "Save" mode. The only other major contributor to DC consumption in a JB Premium's "sleep" mode is the 4D Systems uLCD module, which of course is always powered up in a fully "active" mode. 4D's datasheet specs it at 1Watt (absolute max) as well. When the JB is actively charging an EV, the biggest load contributor would probably be the 12Vdc coil power to the AC power relay. The relay nominally draws 2 Watts, so perhaps the maximum full power dissipation of a JuiceBox Premium would be in the neighborhood of ~5 to 10 Watts max. The JB Basic model would be considerably less, probably <100mW standby, <3W active.

 

[chadwick110]

Newbie, untechnical, I NEED HELP, question here:

I have my JB, and need to upgrade the firmware so that I can take advantage of the LEAF's charging timer without the relay cycling on and off.

I have been instructed to follow the instructions on page 65 of the manual, but it is even too technical for me. Is there anyone willing to write up in Dummie style just how in the world I upgrade the firmware? Like, pictures of what plugs into what, super broken out instructions?

I have downloaded Arduino, but have no idea how to use it.

Any help would be appreciated.

P.S. LOVE MY JUICEBOX!

 

[dsinned]

What you wish to do will be quite challenging without a very thorough knowledge of Arduino programming. I speak from experience as for the past several weeks I have been "very slowly" learning, how to modify my JB firmware. However, I have only been comfortable trying to modify "the code" primarily for relatively simple things such as only affect the LCD; nothing in the area of main EVSE functionality. Unfortunately, the eMW documentation does not really help "beginners" understand how to modify their JB firmware. The arduino programming language is a lot like the high level language C++, which looks mostly like a totally foreign language to me. The source code is "documented" with many helpful comments, but generally not enough for a complete understanding of what the code DOES. Many areas of the code are especially difficult to figure out, even with lots of comments. :?

"Open Source EVSE" can be deceiving as that does not mean ANYONE can modify a simple 8bit microcontroller hardware application, especially the firmware. Building H/W kits is one thing, but modifying firmware is quite another. For example, this may explain why the JuiceBox - even in kit form - currently ships from the factory fully "pre-programmed".

It would be nice if open source EVSE vendors could provide "training" classes to their customers, or sponsor end user groups that meet periodically at their company locations to put on "clinics". These would cover such topics as basic/advanced Arduino programming. This would be in the spirit of "DIY" hobbyist activities for people who wish to learn the basics of "how an EVSE works" as well as more advanced presentations on how to modify a arduino based EVSE firmware. Online discussion forums like this can be somewhat helpful as well, but not nearly as effective for these purposes.

Just my two cents . . . and I LOVE my Juicebox too!!! :mrgreen:

 

[valerun]

Newbie, untechnical, I NEED HELP, question here:

I have my JB, and need to upgrade the firmware so that I can take advantage of the LEAF's charging timer without the relay cycling on and off.

I have been instructed to follow the instructions on page 65 of the manual, but it is even too technical for me. Is there anyone willing to write up in Dummie style just how in the world I upgrade the firmware? Like, pictures of what plugs into what, super broken out instructions?

I have downloaded Arduino, but have no idea how to use it.

Any help would be appreciated.

P.S. LOVE MY JUICEBOX!

Thanks chadwick110!

Do you have an FTDI cable? If not, get one (from us or any other DIY electronics shop - sparkfun, adafruit, etc). Once you get it, you would plug it into the programming header of your JuiceBox and connect to USB of your PC where you have installed your Arduino IDE. See page 67 in our manual (https://docs.google.com/a/emotorwerks.com/document/d/127joe-QgHYRQVD4Zl2-oZO3A9gRjJZC4ReH_2jIM_x0/edit#" onclick="window.open(this.href);return false for a photo of how to plug in FTDI.

If you are not planning to make any changes to the firmware (i.e. just want to update to the latest version for your board type - which is what, V8.7?), we can build a .hex file for you to upload without using Arduino IDE (you will still need an FTDI cable). Let us know.

Thanks,
Val

 

[valerun]

dsinned - thanks for your suggestions. We are happy to provide space but we will have to get volunteer gurus to help run the sessions. I don't think we can manage this just by ourselves - yet, anyway.