A primary battery is one that can convert its chemicals into electricity only once and then must be discarded. A secondary battery has electrodes that can be reconstituted by passing electricity back through it; also called a storage or rechargeable battery, it can be reused many times.
Batteries Charge Time Calculation  

Example:
Calculate the maximum time taken by a battery to charge by the given details.
Battery Capacity (mAh) = 25
Charge Rate Current (mA) = 30
Solution:
Apply formula:
MTFC (10% Efficiency Loss) = ((BC / CRC) * 11) / 10 = (25/30)*11/10
MTFC (10% Efficiency Loss) = 0.916666 (Hours)
MTFC (20% Efficiency Loss) = ((BC / CRC) * 12)/10 = (25/30)*12/10 = 1
MTFC (20% Efficiency Loss) =1(Hours)
MTFC (30% Efficiency Loss) = ((BC / CRC) * 13)/10 = (25/30)*13/10 = 1.08333
MTFC (30% Efficiency Loss) = 1.083333(Hours)
MTFC (40% Efficiency Loss) = ((BC / CRC) * 14)/10 = (25/30)*14/10 = 1.1666
MTFC (40% Efficiency Loss) = 1.1666 (Hours)
MTFC (No Efficiency Loss) = ((BC / CRC) * 10)/10 = (25/30*10)/10 = 0.83333
MTFC (No Efficiency Loss) = 0.83333 (Hours)