Product Dose


Measuring the charge level

A hydrometer can be used to test the specific gravity of each cell as a measure of its state of charge. Because the electrolyte takes part in the charge-discharge reaction, this battery has one major advantage over other chemistries. It is relatively simple to determine the state of charge by merely measuring the specifice gravity ( S.G) of the electrolyte, the S.G. falling as the battery discharges. Some battery designs include a simple hydrometer using colored floating balls of differing density ,  When used in diesel-electric submarines , the S.G. was regularly measured and written on a blackboard in the control room to indicate how much longer the boat could remain submerged.


Lead-acid batteries lose the ability to hold a charge when discharged for too long due to sulfation, the crystallization of lead sulfate . They generate electricity through a double sulfate chemical reaction. lead and lead ( IV ) oxide, which are the active materials on the battery's plates, react with BATTERY ACID in the electrolyte to form lead sulfate  . The lead sulfate first forms in a finely divided, amorphous state, and easily reverts to lead, lead oxide and sulfuric acid when the battery recharges. As batteries cycle through numerous discharge and charges, the lead sulfate slowly converts to a stable crystalline form that no longer dissolves on recharging. Thus, not all the lead is returned to the battery plates, and the amount of usable active material necessary for electricity generation declines over time.

Sulfation occurs in all lead-acid batteries during normal operation. It clogs the grids, impedes recharging and ultimately expands, cracking the plates and destroying the battery. In addition, the sulfate portion (of the lead sulfate) is not returned to the electrolyte as sulfuric acid. The large crystals physically block the electrolyte from entering the pores of the plates. Sulfation can be avoided if the battery is fully recharged immediately after a discharge cycle.

Sulfation also affects the charging cycle, resulting in longer charging times, less efficient and incomplete charging, and higher battery temperatures.

The process can often be at least partially prevented and/or reversed by a desulfation technique called pulse conditioning, in which short but powerful current surges are repeatedly sent through the damaged battery. Over time, this procedure tends to break down and dissolve the sulfate crystals, restoring some capacity.

Higher temperature speeds both desulfation and sulfation, although too much heat damages the battery by accelerating corrosion