What is the preferred method for charging NiCad batteries?

What is the preferred method for charging NiCad batteries?

• A. Constant current charging
• B. Constant voltage charging
• C. Pulse charging
• D. Trickle charging

Answer: (A)

NiCd cells are charged best with a constant current source because their chemistry responds primarily to the amount of charge put in over time, not to a fixed voltage. By delivering a steady current, the charge rate is predictable and uniform for all cells in the pack, reducing the risk of overcharging any cell. Voltage across NiCd packs rises as they charge, and relying on a fixed voltage can push excessive current into cells with lower internal resistance, causing overheating or damage. Termination is then done by a detection method such as a temperature rise, a negative delta V, or a timer to stop charging when full. After the main charge, a very small trickle current is sometimes used to maintain full capacity, but the initial charging should be constant current. Pulsed charging exists in some systems, but constant current charging is the standard, reliable method.

NiCd cells are charged best with a constant current source because their chemistry responds primarily to the amount of charge put in over time, not to a fixed voltage. By delivering a steady current, the charge rate is predictable and uniform for all cells in the pack, reducing the risk of overcharging any cell. Voltage across NiCd packs rises as they charge, and relying on a fixed voltage can push excessive current into cells with lower internal resistance, causing overheating or damage. Termination is then done by a detection method such as a temperature rise, a negative delta V, or a timer to stop charging when full. After the main charge, a very small trickle current is sometimes used to maintain full capacity, but the initial charging should be constant current. Pulsed charging exists in some systems, but constant current charging is the standard, reliable method.