This is where generator batteries come in. They deliver a high starting current in order to start a generator. They use an electrolyte which contains sulfuric acid. The interaction between the electrolyte and lead inside the battery causes a chemical reaction which, in turn, produces electrical energy. Generator batteries can be flooded plate types, gel cell types or absorbed glass matt batteries.
Flooded type generator batteries are the most common type. Usually, the cells are not sealed so the user can refill the electrolyte fluid in this type of battery. The electrolyte can be replenished by pouring it into small ½ inch holes on top of the battery casing.
The plastic housing used for flooded type generator batteries will have one or more lead cells built in it. Each cell has a grid of lead plates which are soaked by the liquid electrolyte. The lead grid is not supported at the edges of the housing, thus making this type of battery the weakest in terms of mechanics and structural integrity.
Because the housing is not sealed, the user has to be careful when pouring in the corrosive electrolyte or he might burn himself.
Another type of generator battery is the gel cell. Gel cell types are similar to flooded types. However, the electrolyte is mixed with a thickening agent such as fumed silica. This mixture produces a thick gel.
Therefore, even if the battery container cracks or breaks, the battery will still function. Thats because the gel will not pour out of the container compared to a pure liquid electrolyte. In addition, the thickening agent prevents battery stratification by preventing the movement of electrolyte.
Gel cells are sealed and cannot be refilled with electrolyte. To prolong its life, the rate of charge has to be carefully controlled. Furthermore, the set points of the charging equipment has to be recalibrated since gel cells use lower charging voltages than flooded cells.
The newest kind of generator battery is the absorbed glass matt or AGM battery. This kind of battery does not use a gel-form electrolyte. Instead, it uses a fiberglass like separator to contain the electrolyte. The separator, lead plates and the battery container are tightly bound and compressed. This arrangement makes the AGM the sturdiest of all battery types. It is spill proof, impact resistant and can withstand extreme vibrations. An additional advantage is that AGMs use the same voltage settings for charging as flooded cell types.
Like the gel cell, an AGM battery cannot be refilled with electrolyte. Thus, charging must be carefully monitored.
Each type of generator battery has its own advantage and disadvantage. It is up to the specifications of the generator and the preference and budget of the user to determine what type should be used.