Which of the following is TRUE about the charging conditions for lead-acid batteries?

Charging lead-acid batteries with constant potential is the best practice because it ensures that the battery receives a steady voltage throughout the charging process. This method allows for the effective replenishment of the electrolyte, promotes uniform charging, and reduces the risk of overcharging, which can lead to damage, such as thermal runaway or gas generation.

Maintaining a constant voltage helps to manage the charging characteristics of lead-acid batteries more efficiently. It keeps the voltage at an optimal level, which in turn regulates the amount of current entering the battery. As the battery approaches its full charge, the current will naturally taper off, minimizing the risk of overcharging and extending the battery's lifespan.

Other methods of charging, such as using a variable current or only charging when the battery is fully discharged, do not provide the optimal conditions for battery health and performance. Additionally, charging with alternating current is not suitable for lead-acid batteries, as these batteries require direct current to charge effectively. Thus, the principle of constant potential charging supports the safe and effective maintenance of lead-acid batteries.