Did you know that certain types of batteries suffer from a condition known as “memory effect”? Memory effect is observed in rechargeable batteries such as Ni-Cd and Ni-MH batteries. When these batteries are not fully discharged before recharging on a continuous basis, the batteries tend to remember the shortened cycle. This results in reduced capacity or the length of use per charge.
Here we will unveil the mystery behind memory effect in more detail. You will also learn which types of batteries are affected by memory effect and which are immune to this problem.
What is “Memory Effect” in Batteries?
Memory effect, also known as lazy battery effect or cyclic memory effect, is caused due to incorrect charging of batteries. The problem occurs when the batteries are constantly partially discharged before recharging. This causes the battery to forget its normal capacity, thus reducing the length of use per charge. The battery does not fully drain all the way down and cycles less of active material than its full capacity.
An example will help in further understanding the problem of memory effect. Suppose that you charge the battery on a regular basis, but do not wait for the battery to fully discharge before recharging. If you recharge the battery when only 50% of its capacity is used, eventually the battery will forget that it has extra capacity. The battery will remain functional at only 50% of its original capacity.
Memory effect occurs due to changes in the characteristics of unused active materials of the battery. When the active materials are not utilized, they undergo a phenomenon known as voltage depression. As a result, the battery performs less than its actual capacity.
How to Solve Memory Effect Problem?
The only way to avoid the “memory effect” is to fully cycle the battery once every three weeks. What this means is that the battery needs to be fully discharged before fully charging it again. The battery can be fully discharged by unplugging the device from the AC adapter and running it on battery until it ceases to function. Once the battery is fully discharged, the battery should be plugged back to the AC adapter.
In this way, the battery will fully cycle its active materials that will effectively solve the problem of memory effect.
Types of Batteries Affected with Memory Effect
Memory effect occurs primarily in Ni-Cd rechargeable batteries. Ni-MH and Li-Ion batteries are also affected by memory problems but it happens to a lesser extent in these batteries. You need to fully discharge and charge these batteries at least once a month to prevent the memory effect issues with these batteries. This will also increase the lifespan of the batteries.
Sealed Lead Acid batteries, on the other hand, are immune to the problem of memory effect. These batteries do not need to be fully discharged and charged to maintain them in optimum condition. On the contrary, fully draining may in fact damage the batteries. This offers more convenience for the users as they do not have to maintain these batteries to keep them in good condition.
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