Lithium-Ion Battery Memory-Introduction, Type and Protection

Memory effect is considered in rechargeable batteries, which causes them to store less power. Battery effect, lazy battery effect, or battery memory are the other terms used for the memory effect. This effect happens when the battery does not discharge each time completely during discharge, which results in residual charging. After repeated charging, that residual charge increases to a point where the battery can retain only a small amount of available charge: only NiCd and NiMH batteries used to display memory influence. Still, recently researchers have also observed it in Li-Ion batteries.

What is the memory effect on lithium-ion batteries

Did you find that your rechargeable batteries don't seem to last as long as they were new The battery memory effect reduces the lifespan of charging a rechargeable battery due to incomplete discharge.

Some types of batteries, such as NiCd and NiMh, may produce a memory effect when only partially discharged before recharging. Such "memory" decreases the efficiency of subsequent charges in a given device, and therefore the potential battery life. Poorly built chargers also can cause the effect.

Diligent battery usage will minimize the memory effect: full discharge than recharge. Through deep discharging and charging cycles, one can recondition batteries with a memory effect. Some chargers also have unique modes for reconditioning the battery.

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New batteries like lithium-ion and lithium-polymer, provide higher power and an increased ability to retain a charge when not in operation, while still having little memory effect when partially discharged.

What kind of batteries have a memory

The memory effect is observed in (rechargeable) nickel-cadmium and nickel-metal hybrid batteries. The true memory effect occurs only rarely. However, most often, a battery can exhibit effects that are merely identical to the 'real' effect on memory. These effects might be temporary and can be reversed with proper battery maintenance, which ensures the battery is still fit for use. Here are the two kinds of batteries which have memory effect:-

1). Nickel Cadmium

The NiCd memory affected the batteries, which were only partially discharged and repeatedly recharged. The consequence was that the cell would only discharge after several partial discharges to the level to which it had been discharged again and again.

In cases where a NiCd was used in a device where it served as a battery backup, the memory effect was apparent. Under normal situations, a mains or other supply was used. Still, the cell was often partially discharged when the supply to the mains was not available and then recharged.

It seems that the NiCd memory effect is not a big problem for most typical applications. Still, it helps if the cell is periodically operated through a full cycle, ensuring it is discharged fully. If the cells are located inside a larger battery, it is essential to discharge them separately (if possible). It would ensure that there is no reverse charging of individual cells because specific cells contain significantly more charging than others. It will help to reduce the NiCd memory effect if suspected by conducting the occasional full discharge/charge process.

2). Nickel metal hydride

Technically, NiMH batteries don't have a "memory effect," but neither do NiCds strictly speaking. Nevertheless, NiMH batteries that experience voltage depletion, often called voltage depression, are similar to NiCd batteries, but the effect is typically less visible.

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Overcharge and inadequate storage can also harm the NiMH batteries (see the NiCd section immediately above this one). Many NiMH battery users don't have to think about the impact of this voltage depletion. So if you're using a gadget that has a flashlight, radio, or digital camera every day for only a short time, and then charging the batteries at night, you'll need to let the NiMH (or NiCd) batteries run down periodically.

How do you protect your lithium-ion batteries

There's plenty of press on how to maintain battery power, but not much about protecting your batteries. It doesn't take long to know what's going to maintain the current battery charge. What is not well known by many people is that the protection of batteries is equally significant. Doing so allows effective operation by the battery.

Here are a few ways to keep your lithium-ion batteries protected.

place your battery at room temperature-

Always keep your battery between about 20 and 25 degrees C. The worst thing that can happen to a lithium-ion battery is full charging and being subject to high temperatures. So don't abandon or charge your mobile device in your car if it's hot out. Heat is by far the most significant factor in reducing battery life for the lithium-ion battery.

Always carry a high- capacity lithium-ion battery-

Over time, batteries deteriorate, whether used or not. A replacement battery would, therefore, not last any longer than the one in use. When purchasing batteries, it is essential to note the characteristics of longevity. Be sure to ask for ones with the latest date of manufacture.

Better to use partial discharges -

Unlike NiCad batteries, lithium-ion batteries do not have charging memory. This means deep-discharge cycles do not necessitate. Also, using partial-discharge cycles is better for the battery. Battery experts suggest that you should allow almost complete discharge of the lithium-ion batteries after 30 charges.

Continuous partial discharges create a condition called digital memory, decreasing the accuracy of the device's power gauge. So let the battery discharge to the point of cut-off, and then recharge. It will recalibrate the power gauge.

Stop discharging lithium-ion batteries entirely.

When a  battery is discharged below 2.5 volts per cell, a battery built-in security circuit opens. The battery appears dead. The initial loader is of no use. Only battery analyzers that have the boost function have a chance to charge the battery again. Also, do not recharge deeply drained lithium-ion batteries for safety purposes, if they have been stored for several months in that condition.

The Final Verdict

Lithium-ion batteries have a minor memory effect as per research. Still, it doesn't affect its battery life, performance, and durability. If you observe that there is a memory effect in your battery, follow the above protection tips to ensure long life.