I ran my Honda CRV battery dead a few times because I either left the key turned to ACCII rather than ACC1 or I left the keys in the ignition while parked with the car still attached for too long. I ended up carrying a lithium battery booster pack that has saved my butt on numerous occasions. My honda requires running the engine through the gears every 250 miles (towing) to keep the transmission lubricated. That seems to help keep the battery charged as well.
The simplest solution might be to install a battery switch at the terminal and save a picture of your radio activation code on your phone to get it up and running again after being disconnected.
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