Memory effect is a term that is thrown around with talking about a rechargeable battery, but there are a lot of misconceptions around what memory effect is. Memory effect is where batteries aren’t able to hold as much charge as they once could.
When a user experiences less capacity in the battery than they once had, they believe that this is memory effect, which is not the case.
The most common reasons for batteries no longer outputting as they once did are the following:
1) Over-Charging: Charging aa rechargeable batteries, even the best rechargeable batteries, for too long will result in the peak voltage dropping off much more quickly than it once used to. It would appear to an end-user that the battery capacity had in fact decreased, however this is not the case. The is more common in high-drain consumer electronics such as handheld devices and digital cameras. The device is expecting to see the higher voltage, else it produces a low battery warning or similar. Some electronic devices which are not high-drain may not even see any difference if the battery has a voltage drop. Over-charging is much more likely with cheap trickle (slow) chargers.