In diesel generator sets, we commonly use lead-acid batteries, which are mainly divided into two types: dry charged batteries and maintenance-free batteries.

1) Dry-cell Lead-Acid Battery: Also known as the dry charged lead-acid battery, its main feature is the high storage capacity of the negative plates, which can retain the charge for up to two years in a completely dry state. Upon use, simply add electrolyte and wait 20-30 minutes before it's ready. Its primary advantages are stable voltage and low cost; however, it has lower energy density (i.e., the amount of energy stored per kilogram of battery), a shorter lifespan, and frequent maintenance requirements.

2) Maintenance-Free Batteries: Maintenance-free batteries, thanks to their structural advantages, consume very little electrolyte, requiring almost no distilled water to be added throughout their lifespan. They also feature shock resistance, high-temperature tolerance, compact size, and low self-discharge. Their lifespan is typically twice that of standard batteries. There are two types of maintenance-free batteries on the market: one that is filled with electrolyte upon purchase and does not require any maintenance during use (no need to add fluid); and another that is sealed with electrolyte already added at the factory, making it impossible for the user to add any fluid. Lead-acid batteries come in series of 2.4V, 4V, 6V, 8V, 12V, and 24V, with capacities ranging from 200mAh to 3000Ah. Diesel generator sets usually use 12V or 24V batteries for starting.