I have 5 remote “On/Off” sensors on my privacy fence gates. The problem is that the batteries do not last a long time. The batteries that the Insteon sensors use are the regular AA non rechargeable type. I was replacing the batteries (rechargeable type) in one of my garden SOLAR lights (after 2 years) and notice that the batteries were 1.2VDC. Hummm, I wonder if the sensors would operate on the1.2 volt rechargeable batteries opposed to the 1.5VDC of the regular batteries. I tested on a spare sensor and it worked fine at the most distant gate location. The nice part of these inexpensive SOLAR garden lights is that they have a chip in them that checks the SOLAR panel output to see if is producing power, if not it disconnects the SOLAR panel from the circuit so that it will not drain the battery at night.
I just completed the project where I took the inexpensive garden SOLAR light ($1USD at Dollar General), removed the LED on the power boost side of the garden light and hooked the battery side of the SOLAR light to the battery contacts in the On/Off sensor. I then mounted the little SOLAR panel part of the light to the top of the gate and wired it to the sensor. I did not leave the battery in the SOLAR light module. The SOLAR panel portion supplies 1.4 volts back to the battery and keeps it topped off.
It has been almost 2 months and the remote sensor is still performing perfectly. The next project is to purchase the larger Garden SOLAR light ($3USD) that uses a 3.2VDC rechargeable battery/circuit in it and try it on my Insteon exterior motion sensors, which use the 3VDC regular batteries.
I will keep you posted with the status of the projects. Time will tell.