My third attempt is to use and optoisolator as RandyR did. A recent 3 day period of overcast weather shut down all three of my GTM relays that were modified to restart when the sun returns. When the sun came out 2 out of 3 of them returned to normal operation. I’m not sure what caused one to fail. I’m hoping that it was because I didn’t have the Voltaic V15 in always on mode but I’m concerned that it may have shut down completely after being without power for too long. I have the culprit on my desk now testing that theory.
My auto restart relay setup is pretty much the same as in the Youtube video I posted in this thread a while back except it uses an optoisolator in place of the blue relay on 2 setups. I am also using the stock GTM battery. I’m powering it with either a 6W/6V or 10W/18V panel connected to a Voltaic V15 in always on mode. I also have the microcontroller set to return the GTM to pairing mode so that I can ping or message to confirm it’s operational. Having the device auto reset and being able to confirm it is working could save me hours of time and miles of driving. I’m pretty sure when I get it figured out goTenna will release a purpose built relay that works perfectly!
The GTM does use about twice the power in pairing mode (white light flashing but paired device not in bluetooth range). I’m toying with the idea of using a bigger GTM battery and just splitting the solar panel power to the microcontroller/GTM. This would omit the Voltaic battery and one less possible failure point. I’m also pretty certain the V15 wastes a bit of power in always on mode. I think this may result in several un-needed power on “presses” as the sun comes and goes but other than that I can’t think of a downside. I’d appreciate any thoughts on that idea or anything else.