RE: Charging a lawn tractor battery for the field box
I use a lawn tractor battery from Walmart that has 280 cc amps for everything except the 7 amp battery inside the field box to operate the power panel. Charge lasts a month at least, depending on how many times you charge the flight batteries, and it can be charged with your 5 - 10 amp field charger off the car battery. Costs $28 + core charge. Last one I had lasted about 2 years. The 240 cc amp version is $24.