What is a characteristic of 'wet' batteries?

'Wet' batteries, also known as flooded batteries, are defined by their use of liquid electrolytes, typically a mixture of water and sulfuric acid. This characteristic is crucial because the presence of liquid electrolytes plays a significant role in the battery's chemical reactions, allowing them to store and release electrical energy effectively.

In addition to containing liquid electrolytes, wet batteries are often sensitive to orientation; they must remain upright to prevent leakage of the electrolyte. This is essential to maintain functionality and safety, as a spill can lead to hazardous conditions and operational failure.

While some batteries may be designed for portability or can withstand extreme temperatures, these traits are not defining characteristics of wet batteries specifically. In contrast, batteries with solid electrolytes or those described as lightweight would reflect completely different designs or types, such as dry or lithium-ion batteries. Hence, the correct choice accurately captures the fundamental nature of wet batteries, focusing on their liquid electrolyte composition and the need for upright positioning.