Battery Charging and Discharging Process
A battery tends to be discharging for much longer periods of time than when it is being charged. After all, a car sits for longer periods of time than when it is being driven. Hence, lead sulfate is produced faster than it can be reverted into lead, lead dioxide, and water (see equations above). When the lead sulfate is left sitting for long periods of time, the initially spongy lead sulfate hardens and forms crystals. Unlike the spongy lead sulfate, these crystals cannot be reverted back to active material (lead and lead dioxide). More crystals on lead plates mean less active material is left to be used for the battery’s chemical reaction. A battery is effectively dead when there is simply not enough active material left to start a vehicle!
Lead sulfate crystallization causes more than 3/4 of batteries to fail before their designed lifespan!!
Sulfation
Revival and Restoration of Dead Batteries
As long as there is still active material in the battery and the plates aren’t shorted, any battery that fails due to lead sulfate crystallization has a chance of being revived and reused. This is not only limited to car batteries, but to ALL lead acid batteries!
The graph below shows the revival process of a 45 Ah Ca-Ca battery that had failed 2 years ago due to shelf sulfation. Note how the impedance and CCA (Cold Cranking Amperes) are inversely related. The CCA of the battery, initially at 112 increased gradually up to 321. The battery was originally rated at 360 CCA, and it takes about 180 CCA to crank a car.
In this particular example, the battery was revived in approximately 6 hours or so. Do note that not all batteries can be revived in such short periods of time. The speed of revival depends on the degree of sulfation the battery suffers from. Revival can take up to weeks if a battery is badly sulfated as more time is needed to break the lead sulfate crystals.
Almost As Good As New
We have meters and equipment to indicate how well a reconditioned or revived battery works. A score of tests are performed on that battery, including discharging and charging to see how well the battery holds its charge. Measurements such as cold cranking amps and internal impedance are also taken to ensure the battery’s health.
