Tractor Load Example
A user in Arizona wants to be able to drive and then leave his truck parked for 60 hours in Minnesota and have it able to start when he returns. When the truck is not running, there is a constant load on a battery from a security electronics GPS unit. This unit operates 24 hours per day and the tractor is parked for 60 hours. The security unit amp draw is measured as 0.550 amps steady state.
The total 60 hour energy consumption would then be 0.550 amps x 60 hours = 33 A-h x 12.5 volts = 412 W-hr. (0.412KW-hr), as per Example "b" above.
This same user again travels to Arizona and wants to be able to then leave his truck parked for 168 hours in Minnesota and have it able to start when he returns. When the truck is not running, there is a constant load on a battery from a security electronics GPS unit. This unit operates 24 hours per day and the tractor is parked for 168 hours. The security unit amp draw is measured as 0.550 amps steady state. The total 168 hour energy consumption would then be 0.550 amps x 168 hours = 92.4 A-h x 12.5 volts = 1,155 W-hr. (1.155 KW-hr), as per Example "d" above.
For both examples, the user will need a solar system that could supply a continuous charge of seven watts per hour at 14 volts to maintain the batteries.