asimba2
Well-known member
Looks like the difference between 20 amps and 25 amps is about 4 miles per hour of charging. Is this thing safe at 25 amps?
OpenEVSE - Open Source Charging Station
- Thread starter chris1howell
- Start date
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asimba2
Well-known member
I have a NEMA 14-50 outlet and 6/3 wiring, so the 30 amp breaker is the limiting factor. I can shove a 40 amp breaker in there to solve that problem. I mainly want to know what is safe to run through these openevse units. Every picture I see on the internet show them set at 16, 20 or 24 amps.
Bob
Well-known member
The OpenEVSE is limited by the relays and the wiring into and out of the relays.
If you use the supplied TE T9A series relays, then you are limited to 30A.
If you use QC connections to the relays, then you are wise to stop at 25A, because even if the relays can handle 30A, the connectors have too little metal for more than that.
I have an OpenEVSE with T9A relays and QC connections to the relays. I operate at 24A and have no trouble. I took a thermal photo of my OpenEVSE running at 24A, just to see how much heat was being generated by each part of the system. The QC connections actually showed a bit of heat, as did the relay. The hottest spot in my system was at the end of one of the QC terminals, where it entered the relay. That point was 17 degrees C hotter than outside air. That is safe, but shows that the connection really is a limitation.
If you use larger relays, then there is no inherent current limit.
Bob
If you use the supplied TE T9A series relays, then you are limited to 30A.
If you use QC connections to the relays, then you are wise to stop at 25A, because even if the relays can handle 30A, the connectors have too little metal for more than that.
I have an OpenEVSE with T9A relays and QC connections to the relays. I operate at 24A and have no trouble. I took a thermal photo of my OpenEVSE running at 24A, just to see how much heat was being generated by each part of the system. The QC connections actually showed a bit of heat, as did the relay. The hottest spot in my system was at the end of one of the QC terminals, where it entered the relay. That point was 17 degrees C hotter than outside air. That is safe, but shows that the connection really is a limitation.
If you use larger relays, then there is no inherent current limit.
Bob
asimba2
Well-known member
Exactly what I wanted to know, thanks so much!
I just started using an OpenEVSE with a RTC installed. The delay timer worked perfectly last night, starting my charge at 11:07 PM when my off-peak rate starts. I noticed today that the unit reset to Green mode. Does that mean I have to set the delay timer each time I want to charge? Is there any way to set the delay timer as the default status?
Thanks!
Thanks!
First I wanted to say thank you to all who have help develop OpenEVSE and made this information publicly available.
I have a question about separating some of the components of the EVSE and the possible distance limitations.
One scenario would be to have the body of the EVSE inside a secure location, then using standard electrical wire inside conduit extend the connections for the J1772 to a small junction box where the car would be, then attaching a reasonable length J1772 cable with connector. This would expose only some conduit, a junction box, and the final cable to theft/vandalism. Another scenario would be similar, but moving the relays to the exposed junction box where the J1772 cable gets attached.
Could this be extended for approximately 100 feet without impacting functionality?
I have a question about separating some of the components of the EVSE and the possible distance limitations.
One scenario would be to have the body of the EVSE inside a secure location, then using standard electrical wire inside conduit extend the connections for the J1772 to a small junction box where the car would be, then attaching a reasonable length J1772 cable with connector. This would expose only some conduit, a junction box, and the final cable to theft/vandalism. Another scenario would be similar, but moving the relays to the exposed junction box where the J1772 cable gets attached.
Could this be extended for approximately 100 feet without impacting functionality?
asimba2 said:
I think the OpenEVSE capacity is limited by the relays and wiring used internally. I just bought one from GlennD that uses the same 80 amp relay from the Juicebox, and I'm running it at 40 amps. The kit sold on the OpenEVSE website uses 30A relays and fuses, I believe. The software itself can handle up to 80 amps.
nds said:
Not at all, but I was mostly just clarifying the reason the software had a limit. Generally, software's limits are entirely artificial. In this case, it's a physical/legal limitation being enforced with software.
Unfortunately, the software has no safe or accurate way to measure the ampacity of the wiring, so I guess you shouldn't set it to 80A if you have a 30A circuit…
chris1howell
Well-known member
I have been very busy working to improve the OpenEVSE experience. I have been redoing all the build guides,. They are currently in Wiki format and take a ton of time to create. Now I am building them in a real guide system Dozuki from the folks at iFixit. It works so well I can create a guide from a smartphone while I build. Please check the online guide and/or the tablet/smartphone app out and let me know what you think here:
Online
http://openevse.dozuki.com/Guide
Tablet/Smartphone Listed on main page as "OpenEVSE"
http://www.dozuki.com/Apps
Online
http://openevse.dozuki.com/Guide
Tablet/Smartphone Listed on main page as "OpenEVSE"
http://www.dozuki.com/Apps
nds said:
The RTC opens a window. If you are within that window and unplug the car you will get the green ready screen. When the off time comes up it will go back to the RTC waiting mode. With it plugged in and the charging is finished then you get the yellow connected display.
nds said:
The RTC opens a window. In that window it operates normally. If you are within that window and unplug the car you will get the green ready screen. When the off time comes up it will go back to the RTC waiting mode. With it plugged in and the charging is finished then you get the yellow connected display.
goelectric2014
Member
- Joined
- May 20, 2014
- Messages
- 12
has anyone used these?
http://www.emotorwerks.com/products/online-store/product/show/44-customizable-juicebox-an-open-source-level-2-15kw-ev-charging-station" onclick="window.open(this.href);return false;
http://www.emotorwerks.com/products/online-store/product/show/44-customizable-juicebox-an-open-source-level-2-15kw-ev-charging-station" onclick="window.open(this.href);return false;
I have an OPEN EVSE from a year ago that I wanted to change to the Max amps from 16a to 24a since I'm using it with a 6.6kw leaf. The adafruit display buttons don't seem to work, LCD does however. so I figured I could just use my serial cable to change it. The software part has never been my strong suit, but I have messed with the Arduino IDE and serial monitor a bit. Could some one give me a brief walk through on setting up the CLI function using a serial cable? Does the board need AC power. I assumed not...
Thanks.
Thanks.
Chris used to ship them out with the button disabled. If you are near Anaheim I will be happy to reprogram it for you with modified firmware. The stock is in 5A steps from 10A to 80A. I use 2A steps from 10A to 50A. There is currently no cables sold over 50A since they had problems overheating.
The CLI works fine in the Arduino serial monitor. If you add the OpenEVSE to the board selection it sets the baud. in any event it is 38K.
A Stock FTDI cable plugs right in. and sense it has power I assume it will power the board.
A Stock FTDI cable plugs right in. and sense it has power I assume it will power the board.
