It occurred to me that perhaps the inverter has this capability. I'm looking at a Growatt 5000es and per the user manual, there is a battery low temp cutoff. I like your idea though of also using warmers. So that's what I'm going to do instead of an Arduino circuit breaker.I'm just guessing here, but I wonder if there are AIO's where you could run a serial, UART, or CANBUS to connection them, and run a simple command to stop the charger, based on your Arduino or Raspberry Pi monitoring response.
I hate reinventing the wheel, do you mean just an ordinary wall thermostat for central air conditioners? Kindly link to one such unit.Why use an Arduino when they sell perfectly good thermostats for less than $10, I wonder.
How might a thermostat like that be able to sense the temperature directly from the battery? Seems like it'd only be watching ambient. Which is good for switching off, I'm just wondering about the heater you're talking about.https://www.amazon.co.uk/Europart-Universal-VC1-Refrigerator-Thermostat/dp/B013D9UCOI ?
Just search for fridge thermostat, wall thermostat would be difficult to find for low temperatures, or... if you find a thermostat that will open/close a contact at a certain temperature, and doesn't carry the amperage you need, just use a 12/24/whatever volt relay to do that.
Just wire it so it will open the contact (cut power from the panels) under a certain temperature.
You could use a two-way relay (most of them are) to divert the PV power to a coil under the batteries so it warms them instead of charging... until they're warm enough, and the relay switches.
This one will control my cell heaters:I hate reinventing the wheel, do you mean just an ordinary wall thermostat for central air conditioners? Kindly link to one such unit.
How might a thermostat like that be able to sense the temperature directly from the battery?
One good reason not to, @Samsonite801 mentioned: Reconnecting inverter without charging caps using a resistor can cause magic smoke. A thermostat would cycle off and on without doing any protective charge-up.Why use an Arduino when they sell perfectly good thermostats for less than $10, I wonder.
How would you know where to set the dial to cut off at the correct temperature?
Reconnecting inverter without charging caps using a resistor can cause magic smoke