Fully charged 6-volt rechargeable batteries work by producing a chemical reaction between the battery's sulfuric acid and lead plates once hooked up to a load. This reaction covers the positive and negative plates with lead sulfate, which decreases the available voltage. Once the plates are covered, batteries must be recharged before working properly. Recharging recycles and converts lead sulfate back to sulfuric acid.
Six-volt rechargeable batteries rely on an outside source to give them their power. They are lead acid based and unable to produce any voltage on their own. Instead, they take the charge from the charger and store it for future use. The amount of charge held by a battery is determined by the size of its battery plates and the amount of electrolytes available inside the battery. Some brands of lead acid-based batteries require the addition of water to maintain the proper electrolyte balance and extend the life of the battery.
Six-volt rechargeable batteries are sometimes placed in a series to produce the strength of battery needed to run larger vehicles such as RVs or boats. The battery has two lead plates: one lead dioxide positive plate and one sponge lead negative. These plates are placed in a plastic case, where they are surrounded in water and sulfuric acid.