As far as chargers go......Buy the cheapest, slowest dumb
charger/chargers you can and plug them into the cheapest
electrical timer you can find. Set the timer for a couple hours
a day and you'll always have a fresh set of batteries, you'll
never have to worry about overcharging, and you'll have
more money in your pocket for other toys.

The cheapest charger may only get Nimh near 90% charged if its a Nicad
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The cheapest slowest dumb chargers can easily overcharge a NIMH
battery. That is why they are dumb. By using the timer set for just a
couple hours a day you nullify any damage caused by overcharging.