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The memory effect in batteries: what it is and how to prevent it

The memory effect, lazy battery effect or battery memory can happen if a battery is repeatedly charged before all of its stored energy is depleted. This in turn will cause the battery to ‘memorise’ the decreased life cycle. Next time you use it, you may notice a significantly shorter operating time. Usually, performance itself is not affected.

The true memory effect versus similar problems

The memory effect is observed in (rechargeable) nickel-cadmium and nickel-metal hybrid batteries. The true memory effect occurs only occasionally, however. More frequently, a battery may show effects that are merely similar to the ‘true’ memory effect. The main difference? Often, those are just temporary and can be reversed with proper battery care - meaning the battery is still fit for use.

To restore temporary capacity loss, you may need to completely discharge a battery by leaving it in a torch. Once this happens, make sure to recharge your battery. Be mindful not to overcharge, as this may damage the battery. Smart chargers can help provide just the right amount of energy needed to obtain optimal capacity.

The memory effect on Panasonic eneloop batteries

You do not need to worry about the memory effect in Panasonic eneloop batteries, however. As eneloop’s voltage is higher than that of conventional NiMH batteries, sufficient voltage remains at all times. As such, the memory effect is virtually nonexistent in eneloop batteries. Therefore, you can charge your batteries at whatever moment you see fit.

When in doubt, or if you do want to be 100% certain that the battery is fully charged, you can always use the ‘refresh’ feature on your eneloop charger. This will completely drain the battery and fill it up with a fresh charge.