The 101 is 36 volts. You will need 3 batteries, either 27 series or 31 series. The 31 are larger and heavier, but will last even longer running time. But I doubt you'll need that much running time. Batteries are a personal choice. I use the Sam's club or walmart one's as I have not seen any advantage to running the more expensive batteries. Except you might get 4to 5 yrs out of them instead of 3 to 4 yrs. On board charger, 3 bank 10 + amps each bank. Again, pick a major brand, they are all quite good. Always charge your batteries at the end of the day! A quality charger you leave plugged in till your ready to go back out.