A rectifier unit used to change alternating to direct power for charging a storage battery is called as a battery charger. It is also known as charger. A battery generally consists of an anode, a cathode, and an electrolyte. The charge current depends upon the technology and capacity of the battery being charged.

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.

A battery is an electrochemical cell (or enclosed and protected material) that can be charged electrically to provide a static potential for power or released electrical charge when needed. The battery charge time calculation formula is used to calculate the maximum charge time of batteries, based on the battery chemistry and the charge rate current.

The normally accepted standard for efficiency loss is 20%. Although 10% and no loss are virtually impossible, we have included the potential for reasons of understanding. 30% and 40% are far more likely than 10%. If loss is above 40%, you need to attempt to find the reason by changing the charger or replacing the battery.

Formula

BC - Battery Capacity (mAh)

CRC - Charge Rate Current (mA)

MTFC - Maximum Time To Full Charge (Hours)

MTFC (10% Efficiency Loss) = ((BC / CRC) * 11) / 10

MTFC (20% Efficiency Loss) = ((BC / CRC) * 12) / 10

MTFC (30% Efficiency Loss) = ((BC / CRC) * 13) / 10

MTFC (40% Efficiency Loss) = ((BC / CRC) * 14) / 10

MTFC (No Efficiency Loss) = ((BC / CRC) * 10) / 10

Example:

Calculate the maximum time taken by battery to charge by the given details.

Battery Capacity = 1600 mAh

Charge Rate Current = 400 mA

Solution:

Apply formula:

MTFC (10% Efficiency Loss) = 4.4 (Hours)

MTFC (20% Efficiency Loss) = 4.8 (Hours)

MTFC (30% Efficiency Loss) = 5.2 (Hours)

MTFC (40% Efficiency Loss) = 5.6 (Hours)

MTFC (No Efficiency Loss) = 4 (Hours)

For NiMh batteries, for example, this would typically be 10% of the battery capacity rating for 10 hours. Other chemistries, such as Li-ion batteries, will be different.