What does sulfation mean in a lead–acid battery?

Often, the term most commonly heard for explaining the performance degradation of lead–acid batteries is the word, sulfation. Sulfation is a residual term that came into existence during the early days of lead–acid battery development.

What happens when lead oxide reacts with sulfuric acid?

The reaction of lead and lead oxide with the sulfuric acid electrolyte produces a voltage. Supplying energy to an external load discharges the battery. During discharge, both plates convert to lead sulfate (PbSO 4) and the electrolytes becomes less acidic.

Why does lead sulfate accumulate on negative batteries?

Lead sulfate accumulation on the negatives: This is the natural consequence of hydrogen evolution from the negative plates that eventually vents out of the batteries. This loss of hydrogen results in a charge imbalance between the positive and negative electrodes.

What is the reaction product of a lead-acid battery?

The reaction product is a divalent lead salt. Fortunately, the reaction is kinetically very slow. Two important observations follow immediately. First, the life of lead–acid battery is finite because the positive lead alloyed grids will eventually disappear by natural corrosion.

What happens if a lead acid battery runs away?

Under normal conditions, constant voltage charging of lead–acid batteries shows a decrease in current approaching an asymptotic limit at a very low current. In the case of the thermal runaway, the current can rise to the limit of the power supply delivering the current. The Joule heating can boil the electrolyte resulting in a venting of steam.

What causes a battery to sulfate?

“Sulfation” (as a recrystallization effect) occurring in very old batteries. Inter-cell connector failure. Positive electrode active material softening and shedding. lead sulfate accumulation on the negative plate. It should be clear that these failure modes constitute the set of failure modes that have been assigned the general name of sulfation.