Watering the Electric Truck Battery

The electrolyte in a forklift battery is made up of sulfuric acid and water. It conducts electricity by providing for the transport of ions between positive and negative plates within the cells. In a lead acid battery, the electrolyte also participates in the chemical reaction that occurs during charging and discharging of the cells.

This is apparent through hydrometer readings since the electrolyte increases in sulfuric acid concentration (seen as an increase in specific gravity, or density) as the battery is charged.

Because the electrolyte is a participant in the electrochemical reaction, the concentration of sulfuric acid must not be altered from that recommended by the battery manufacturer. A battery hydrometer is used to verify the manufacturer’s specific gravity numbers when all cells are in a fully charged (equalized) condition.

How often do I add water to the battery?

The battery loses electrolyte volume over time as a result of evaporation (accelerated by any battery heating that may occur) and hydrolysis of the water. This water loss must be made up before the level of electrolyte drops below the tops of the plates. Any electrolyte level above the tops of the plates is acceptable, as long as overfilling does not occur. Hard–working, full–time lift truck operation will mean weekly checking of the electrolyte level. An increase in the amount of water needed is a sign of a battery or charger problem. As a battery charges, the electrolyte level rises. Many truck operators are encouraged to add water after charging to avoid overflow, even though watering before charging ensures complete mixing of the electrolyte. This can be important if the battery is exposed to freezing temperatures.

Do I add acid to the cells?

Under normal conditions, only water is lost during battery operation. Addition of acid is only warranted when the electrolyte has been flushed out, or cells have overflowed repeatedly during charging. If you feel that acid must be added to your battery, see your battery serviceman.

Does it matter if the cells overflow?

Overflow brings acid into contact with metal surfaces, such as the battery case and lift truck components. This causes serious maintenance problems. If overflow occurs, the battery should be removed from the lift truck and thoroughly rinsed with water. The lift truck compartment also should be cleaned. Overflow can be avoided by using a level–sensing filler nozzle for your watering hose.

Should the caps be opened during charging?

Leave the caps in place during all phases of battery operation and charging. Acid mist will issue from cells left with caps open, especially during charging. Faulty vent caps will also spray electrolyte across the top of the cells. Replace caps that do not seal properly or that have clogged vent openings. Cracks in the cell cover, or gaps around battery posts, will also allow acid mist to escape. Have defective covers repaired or replaced. If the cap is loose because of a broken vent opening, a threaded replacement can be inserted by your battery serviceman without the expense of replacing the cover.

Why does my battery boil on charge?

Moderately vigorous bubbling, or "gassing," takes place during charging after the 80 percent point has been reached. The point at which this occurs is known as the gassing voltage: 2.35 volts/cell. This is not boiling, but the release of hydrogen and oxygen resulting from hydrolysis. Gassing does not require elevated temperatures to occur. (If the battery exceeds 110 degrees during any phase of charging or use, disconnect it and allow a cool–down period.) Any unusual temperature rise, fuming or sputtering from individual cells, is an indication ry discharge test and evaluation.

What should I do with a battery that smells strongly of acid?

Industrial lead acid batteries that are properly cared for do not emit strong odors. What some people refer to as an acid smell is the result of wet corrosion products left on top of the battery or between the cells. An individual cell that has failed may also emit strong sulfide odors. In either situation, attention by an experienced battery serviceman is required.

For more information, contact Arcon Equipment Inc. (440) 232-1422.