What causes a lead acid battery to fail?

If you are not familiar with lead acid batteries, see our article What is a lead acid battery. Ironically one of the most common reasons for battery failure is not an actual failure of the battery itself, it is people thinking the battery is dead.

Do lead acid batteries degrade over time?

All rechargeable batteries degrade over time. Lead acid and sealed lead acid batteries are no exception. The question is, what exactly happens that causes lead acid batteries to die? This article assumes you have an understanding of the internal structure and make up of lead acid batteries.

Can You overcharge a lead acid battery?

Myth: The worst thing you can do is overcharge a lead acid battery. Fact: The worst thing you can do is under-charge a lead acid battery. Regularly under-charging a battery will result in sulfation with permanent loss of capacity and plate corrosion rates upwards of 25x normal.

What happens if a lead acid battery doesn't start a car?

Just because a lead acid battery can no longer power a specific device, does not mean that there is no energy left in the battery. A car battery that won’t start the engine, still has the potential to provide plenty of fireworks should you short the terminals.

What happens if a lead acid battery is flooded?

If lead acid batteries are cycled too deeply their plates can deform. Starter batteries are not meant to fall below 70% state of charge and deep cycle units can be at risk if they are regularly discharged to below 50%. In flooded lead acid batteries this can cause plates to touch each other and lead to an electrical short.

What happens if you charge a lead-acid battery repeatedly?

Over time, the repeated charging and discharging of a lead-acid battery can cause the plates to degrade and the electrolyte to lose its effectiveness. This can lead to a decrease in the battery’s capacity and lifespan. In the next section, I will discuss the lifespan of lead-acid batteries and factors that can affect it.