How do the different types of NiMH and NiCD chargers work?
There are basically 3 types of chargers for NiCD or NiMH. First, there is the slow, or ‘dumb’ charger that charges at a rate that won’t destroy a battery when it’s full and overcharging. These chargers take 12 hours or more to charge the batteries the charger was designed for. They continue to charge at this rate as long as the charger is connected to the battery. These chargers can charge NiCD or NiMH but it’s better for the batteries if they are not left charging for days at a time. Second, there is the timer charger. These chargers take about 5 hours to charge an empty battery (of capacity the charger was designed for). There is a timer that stops the charging or reduces to a trickle rate after a fixed period. These chargers can under-charge or over-charge depending on battery capacity and how far discharged the battery was at the start of charge. These chargers work at a rate that can overheat a battery that’s being overcharged. Then there are the ‘smart’ chargers. These generally