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What is Stratification?

If you've spent any time reading the blogs or other pages on this site, you have probably seen the term "stratification" being used, but what does it mean?

stratification process

A Little Battery Background


Before we can talk about stratification, we have to cover some information about a battery and how it works.

Lead acid batteries have been around for over 100 years and, really, haven't changed much in that time. The materials and methods may have changed, but the basic premise of lead plates submerged in electrolytes is still the same. Some batteries require the user to add water to compensate for evaporation over time.

How a Battery Works


A normal vehicle battery is usually a 12V system. The 12V battery has six cells set in a row to generate around 12.6V. The cell is made up of two lead plates. The positive plate is covered with a lead dioxide paste, whereas the negative plate is made of sponge lead. There is an insulating material separating the two plates. The plates are immersed in a water and sulphuric acid electrolyte mixture. Each cell stores 2.1V.

Lead acid batteries don't create their own voltage, they only store it. The power has to be generated from another source like an alternator, solar panel, or wind turbine. A lead acid battery is only a storage device.

A fully charged battery is connected to a load like lights, radio, and other equipment. The chemical reaction between the lead plates and the sulfuric acid creates the electricity that is needed.

Battery stratification occurs when the sulfuric acid begins to concentrate at the bottom of the battery. The stratification process increases the build-up of lead sulfate.

The chemical reaction that produces the electricity also causes lead sulfate to begin to coat the positive and negative plates. This process is called sulfation and leaves a yellow build-up on the plates. This normal process continues as the battery discharges, causing more and more sulfate to cover the lead plates and the voltage begins to lower from the full charge amount of 12.6V.

Once the battery is fully discharged, the voltage drops to 10.5V and the plates are almost fully covered in lead sulfate. If the battery drops below 10.5V, it will become severely damaged. As you can see, there isn't much difference between a fully charged battery and a dead one. That's only a decrease of 16%.

The lead sulfate that is covering the plates is a soft material and can be converted back into lead and sulfuric acid through the use of a CTEK smart charger. If a battery is not immediately recharged, the lead sulfate will begin to crystallize and will be unable to be repaired by a standard charger.

A CTEK smart charger can automatically vary its charging voltage, allowing the lead sulfate to be converted back to lead and sulfuric acid. A standard charger doesn't have the ability to vary its voltage, so it won't properly recharge and maintain the vehicle's battery.

CTEK Chargers Recondition Your Battery

CTEK chargers have a patented desulphation function that can extend the battery's life by 2-3 times its normal life. Depending on the charger, there are 4 to 8 steps that it takes while charging the battery. Regardless of the charger, your battery will be reconditioned, maintained, and charged. Let CTEK help you get the most of your battery with our full line of smart chargers.

“Having owned several of another ‘popular’ brand of charger, the CTEK is far and above superior in every possible category. WELL worth the miniscule additional cost. ”

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