WHY CAN CHARGERS USING TIMERS DAMAGE BATTERIES?
Most nicad and nimh batteries are designed to accept overcharge at C/10 rate or lower without immediate damage. C/10 current rate equals battery capacity divided by ten. If these batteries are overcharged above this rate then gas pressure buildup and venting will occur which will lead to premature loss of capacity. To obtain full service life, batteries should be switched to trickle when they are fully charged and not by a timer. All unsophisticated cycler/chargers and some supposedly sophisticated cycler/chargers use timers to terminate to trickle. If the battery capacity divided by 10 is the same or less than the charger current rate no immediate damage will occur. Since most cycler/chargers have only a few current ranges the selection of proper current rate is often not possible. A higher current rate than C/10 is often selected leading to battery damage. If lower current range is selected the timer will switch to trickle before the battery is fully charged. In some very high priced
