Final answer:
Recharging lead-acid batteries must be done with care to prevent A. the release of explosive hydrogen gas that can lead to internal short circuiting, reduced battery life, and potential damage to the electrical system.
Step-by-step explanation:
We have to be careful when recharging lead-acid batteries primarily because A. overcharging can release explosive gases.
The chemical reaction 2H₂O(l) → 2H2(g) + O2(g) occurs during the recharging process, and this can result in the evolution of hydrogen gas, which is highly explosive.
Additionally, if the gas bubbles are formed excessively, they can dislodge some of the PbSO4 or PbO2 particles from the grids, leading them to the bottom of the cell, potentially causing an internal short circuit.
This can not only reduce the battery life but may also lead to damage to the electrical system and cause the battery to leak.
When treated properly, however, a lead-acid battery can be discharged and recharged thousands of times, and in automobiles, it's the alternator that supplies the electric current for reversing the discharge reaction.
It is crucial that the recharging process be carefully monitored to optimize the life of the battery.