As a restaurant owner, you understand that you only make money when your restaurant is open in typical Central New York market hours. Which is why Commercial Janitorial restaurant cleaning crews will work around your schedule, overnight, early morning, daytime, weekends, etc...
The typical charging voltage is between 2.15 volts per cell (12.9 volts for a 6 cell battery) and 2.35 volts per cell (14.1 volts for a 6 cell battery). These voltages are appropriate to apply to a fully charged battery without overcharging or damage.
Capacity is how much capacity energy a battery holds once it is fully charged. The more capacity, the longer a battery will last in any given application. Voltage is the strength. Rechargeable batteries actually develop around 1.4 to 1.45 volts when fully charged even though they are marked as 1.2V.