Parmak Magnum Solar-Pak 12 Low Impedance 12 Volt Battery Operated 30 Mile Range Electric Fence Charger MAG12-SP The sun`s energy charges the fencer by day and a sealed 12-volt rechargeable battery powers the fencer at night. Battery included. Low impedance for maximum power, longer life Charges up to 30 miles of fence  3.1+ joules Weatherproof, portable outdoor model Ideal for large pastures