What determines how long a battery will last?
Unfortunately, this question can't be answered while not knowing the size of the battery bank. Battery capability is expressed by what number Amps for how many hours a battery can last Amp Hour (A.H.) capacity.
Batteries list their reserve capability, that describes the approximate time that they'll run without recharging, on the label or within the user's manual. If your circuit consumes a lot of or less power than this theoretical circuit, you may expertise a shorter or longer battery life. to work out however long your battery can last, calculate the battery's total capability and divide it by your circuit's power.
Most batteries' A.H. capability is declared for the 20-hour rate of discharge. this implies that a battery contains a 1000 A.H. capability if it's discharged over 20 hours, or at concerning 5 Amps-per-hour. However, this same battery would last only 1 hour if the discharge rate was 50 Amps-per-hour because of the high rate of discharge.
The capacity of a battery is defines in terms of Ampere Hour. The Ampere Hour is outlined because the range of hours a battery would last if it takes one Ampere of current. So, if A battery has 10 Ampere hour rating, it'll last for 10 hours if it takes 1 Amperes of current. a 10 Ampere Hour battery can last 5 hours if it takes 2 Amperes of current.