this is a great read for general charging and discharging rules, as well as testing battery capacity (condition)
Of course some of it is specific for the mrc 977 charger, but it lists some very good rules of thumb
The only thing I would add for battery care is to never leave them drained, always recharge after use. Leaving them dead is a quick way to ruin them.
That link:
http://www.modelrectifier.com/resour...977_manual.pdf