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How to test the specific gravity of the electrolyte of the battery?

The specific gravity of the electrolyte of the battery is related to the safety and performance of the battery. The specific gravity of the electrolyte of the battery also has a strong correlation with the performance of the battery. In addition, the specific gravity will also affect the service life of the battery. There is a certain difference in density under electrical conditions, ranging from 1.26 to 1.295.

  1. Determination of specific gravity

When measuring the specific gravity, use a suction hydrometer to slowly suck the electrolyte into the outer cylinder, and observe the scale of the buoy to measure the specific gravity.

The specific gravity of the electrolyte of the lead-acid battery will change with the temperature. The specific gravity of the electrolyte is based on the specific gravity at 20 degrees Celsius. Therefore, the reading on the hydrometer must be converted to the standard specific gravity at 20 degrees Celsius. When the temperature changes by 1°C, the specific gravity changes by 0.0007. Therefore, when measuring the specific gravity, the temperature must be measured. When measuring the temperature, please use a stick alcohol thermometer.

The specific gravity measured at this temperature t°C is St, then the specific gravity S20 when the standard temperature is 20°C is converted by the following formula


S20… is the specific gravity converted to 20°C

St …. is the specific gravity measured at t°C

t ….. is the actual temperature in Celsius of the measured electrolyte

For example, if the specific gravity is 1.280 at 20°C, it becomes 1.273 at 10°C; at 30°C, it becomes 1.287

  1. Add pure water

During repeated discharge, the electrolyte level will slowly drop, so check the electrolyte level regularly and replenish pure water at any time to maintain the proper level. If the electrode plate is exposed due to neglect of water replenishment, it will cause a chain reaction such as an increase in the specific gravity of the electrolyte and vulcanization of the battery, which will damage the electrode plate.

  1. Impurities in the electrolyte and battery life

If the electrolyte contains nitric acid, hydrochloric acid, sulfurous acid, salinity, organic matter, etc., it will corrode the plate, shorten the battery life, and also accelerate self-discharge. In addition, copper, nickel, iron, and manganese will also damage the battery. Increased self-discharge.

When refilling the battery, be sure to use pure water. When rinsing the outside of the battery with water, be sure to close the battery cap tightly to prevent flushing water from entering the battery.

  1. Disadvantages caused by excessive hydration

If the water supply exceeds the maximum liquid level, it will overflow during charging, which will cause the loss of dilute sulfuric acid components, corrode the battery box, and cause insufficient storage capacity due to the low specific gravity of the electrolyte.