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Additional temperature sensor?
OpenEVSE Support
A second temperature sensor can be added to the WiFi i2c connector, it will show up as Temp 4. It is a different bus so it used the default ID. It provides a value only. Only Temperature 2 on the safety controller i2c bus is used by the safety controller to throttle and shutdown.
Additional code or automation from something like Home Assistant would be needed to take action on Temp 4.
Thanks for that detail.
... As added, just simply works!
Thanks,
Martin
See:
Hi, Where is the recommended location to mount the temp sensor on Juicbox V2? Is where I mounted it ok?
For myself, I don't know that there is any "recommended" location for the temperature sensor...
From my own good sense, to catch the most likely fault of a failed/failing mains relay, I've placed my main temperature sensor as seen on:
Kit Assembly Layout OpenEVSE_PLUS_v6.5.1 #30
The main "temp2" temperature sensor is on the side of the relay case to quickly catch a too-hot (failing) relay. (The MCP9808 is on the side of the black relay case, between the two bits of red insulation tape.)
The second MCP9808 that I've added (seen as temp4) is the one at the very top of the case to give a reading of the enclosure temperature, purely for my own reference/interest.
For your Juicebox example, sticking/gluing your temperature sensor onto the top or the side of the white relay case would give an early indication of any overheating problem with the relay. Personally, I'd suggest the left hand side or the top of the relay case, furthest away from the exposed mains contacts!
Good luck!
OpenEVSE Support
The temperature throttling and shutdown on Temp 2 is based on Ambient enclosure temperature not a relay surface temperature. The default firmware sets throttling at 65C and shutdown at 72C, this may be too agressive if the sensor is mounted on the relay.
Another consideration is the relay is extreemly noisy, especially when the contacts are opening and closing.
Givin the tiny volume of air in the enclosure, a overheating relay or loose screw terminals will be detected very quickly. If you really want a sensor on the relay Temp 4 would be the better option as it is not used for throttling and shutdown.
Thanks for those details. Very useful to know... Especially the temperature thresholds.
Myself, I've not seen any problems so far. Good caution from you about the electrical noise from the relay contacts. Also, possibly might there be magnetic coil interference?... I've not investigated, but then again, so far, I've not seen any glitches either.
Thus far, the relay case has stayed well below 65C.
Thanks,
Martin
Martin Lomas
At the moment, only one I2C temperature sensor appears to be supported:
"Temp 2 is from a temp sensor on newer displays MCP9808"
Can a second MCP9808 be used?
(Multiple MCP9808 sensors can be set to a different I2C address...)
My use is to have one temperature sensor on the contactor relay to detect any overheating on the contacts, and a second sensor on the top inside of the case to warn of external heating from such as the sun.
Thanks,
Martin