LETS UNDERSTAND………….HOW BATTERIES WORK?
A lead-acid battery is a secondary (rechargeable) electrochemical device that stores chemical energy and releases it as electrical energy upon demand. When a battery is connected to an external device, such as a starter motor, chemical energy is converted to electrical energy and direct current flows through the circuit.
A battery is made up of cells, each cell is connected in series from the positive (+) terminal of the first cell to the negative (-) terminal of the second cell and so on. Each cell is made up of an element containing positive plates that are all connected together and negative plates, which are also all connected together. They are individually separated with thin sheets of electrically insulating, porous material “envelopes” or “separators” that are used as spacers between the positive and negative plates to keep them from electrically shorting to each other. The plates within a cell alternate with a positive plate then a negative plate and so on.
A battery is created by alternating two different metals such as Lead Dioxide (PbO2) on the positive plates and Sponge lead (Pb) on the negative plates. The plates are then immersed in diluted Sulfuric Acid (H2SO4), the electrolyte. The chemical action between the metals and the electrolyte (battery acid) creates the electrical energy. Energy flows from the battery as soon as there is an electrical load that completes a circuit between the positive terminal connected to the positive plates and the negative terminal connected to the negative plates. Electrical current flows as charged portions of acid (ions) between the battery plates, and as electrons through the external circuit.
NOW…….WHY THEY FAIL
When the active material in the plates can no longer sustain a discharge current, a battery “dies”. Normally a battery “ages” as the active positive plate material sheds or flakes off due to the normal expansion and contraction that occurs during the discharge and charge cycles. This causes a loss of plate capacity which will eventually “kill” the battery. Batteries can also die out due to positive grid growth, positive grid metal corrosion, negative grid shrinkage, buckling of plates, loss of water, deep discharges, heat, vibration, fast charging, and overcharging which all accelerate the “aging” process. Positive grid growth and undercharging are very serious issues causing sulfation – the most prevalent cause of premature battery failure.
During normal operation, a battery builds up sulfate on the positive plates. This is a result of sulfur not being converted back into acid during normal recharging. At first, these deposits are soft and do not do any real damage. Equalized (Recommended by Manufacturers) charging can help convert these back into acid but not everyone has complete awareness and in most cases bothers to perform equalized charging and even if they did, these deposits still build up over time.
The soft deposits eventually change to form hard crystalline…this is the stuff (Main culprit) that does the damage. It expands to 2.7 times its original volume and puts extreme pressure on the cells and contents. It effectively smothers the positive plate and the sulfuric acid strength is reduced. This means runtime is reduced and the battery starts to run very hot under charging as the charging device now provides too much power for the reduced capacity battery.
Batteries that run hot destroy themselves very quickly… in fact industry statistics show that for every 10 degrees you operate a battery over normal recommended temperatures…half the life of the battery is lost!
So, to stop early life failure in a battery, you must control the charge and discharge cycles of the battery in a managed & recommended way.