What Can You Do With The Three Forklift Battery Killers
To paraphrase Douglas MacArthur, "Old batteries never die; they just fade away." Fleet managers know power cells lose their ability to hold a charge and eventually have to be replaced. Understanding why this happens allows you to develop battery handling protocols to get as much life out of them as you can. The three problems are corrosion, sulfation and water loss.
1. Corrosion
There are two types of corrosion: internal and external. A battery is basically sheets of lead immersed in acid. Over time the lead softens and sheds because of the acid's corrosive effect. You can't stop this since it's a side effect of how batteries store and release electricity but you can slow the process. Check the manufacturer's guidelines for the proper acid-water balance in the cell; industry standard is a specific gravity of 1.200 when fully charged. Avoid prolonged overcharging since this greatly accelerates the decay.
People are probably more familiar with external corrosion, the white powdery buildup that appears on the terminals. External corrosion causes the unit to short, draining power even when the forklift is not operating and shortening charge life. Terminals should regularly be washed with an alkaline solution as part of the fleet's battery handling procedures.
2. Sulfation
During the discharge cycle small sulfur crystals form in the electrolyte solution but normally break up during recharging. When a cell doesn't get a full charge, the crystals don't dissolve and coat the lead plates. With less surface area available, the plates cannot hold a charge as effectively. If caught early the sulfation can be reversed by overcharging the unit, although this will accelerate internal corrosion so overcharging should be brief and rare.
When batteries are left on the shelf for weeks or months, permanent sulfation sets in. This cannot be repaired and the cells become inert chunks of lead. If batteries are going to be unused, say if outdoor equipment is being warehoused during the winter, then proper battery handling dictates the cells should be connected to trickle chargers to prevent sulfation.
3. Water Loss
The water in batteries splits into hydrogen and oxygen atoms during use and gasses off, resulting in less water in the solution. This creates two problems. Since the acid does not evaporate, the off-gassing changes the electrolyte balance as the solution becomes more acidic and changes the behavior of the cell. If the liquid level drops low enough to expose the lead plates, this surface area is no longer able to store or release a charge and the capacity drops.
To deal with water loss, top off the cells as part of standard battery handling procedure. Keep the liquid level above the tops of the plates. Never add acid to a battery as this will raise the acidity too high and accelerate corrosion.