Ham Radio General Class Practice Test

When is it acceptable to recharge a carbon-zinc primary cell?

1. As long as the voltage has not been allowed to drop below 1.0 volt

2. When the cell is kept warm during the recharging period

3. When a constant current charger is used

4. Never

The correct answer is: Never

Carbon-zinc primary cells, also known as dry cells, are designed for single-use and are not rechargeable. Attempting to recharge them can lead to leakage, rupture, or even explosion, as these cells do not have the necessary chemical reactions or structural design to handle the recharging process. Therefore, the notion of recharging such batteries is fundamentally flawed; they are meant to be disposed of once their energy is depleted. In contrast, rechargeable batteries, such as nickel-cadmium (NiCd) or lithium-ion (Li-ion) types, are built with materials and designs that allow for safe recharging. The other options may suggest conditions under which recharging could be seen as plausible for different types of cells, but they do not apply to carbon-zinc cells, which should not be recharged at any point. This highlights the importance of understanding the distinction between primary and secondary batteries in ham radio and other applications.