Specific Battery Issues: The Memory Effect
Originally, the terms memory effect or memory problem was coined to describe a cyclic memory problem where the Ni-Cd battery would remember the amount of discharge for previous discharges and limit the recharge life of the battery. In the most technical sense, this does not occur in modern Ni-Cd batteries, which are designed to avoid cyclic memory issues.
The confusion began when, as battery technology advanced, the terms were also used to describe the problem of crystal growth (which causes similar symptoms). Crystal growth can occur when a modern Ni-Cd battery is recharged before it is fully discharged. The crystal growth can eventually prevent the battery from discharging beyond that point and/or cause rapid self-discharge of the battery. While there is an ongoing (and lively) argument as to whether or not the crystal growth issue is or is not a memory effect or memory problem, our concern is how to help our customers avoid or reverse the problem.
You can avoid crystal growth in the battery by either completely discharging it each time it is used or by using a Ni-Cd battery charger which has a built-in discharge circuit.
If you have a Ni-Cd battery which has already been repeatedly recharged without being fully discharged and/or a battery which will no longer take a full charge, you can sometimes reverse the crystal formation by putting the battery through several complete discharge and recharge cycles. The fastest method for doing this is to use a Ni-Cd battery charger with a built-in discharge circuit (as above). However, you can also do this by running the device with the battery installed until it completely dies, and then use a standard charger. |
