Nicads should only be charged on a peak charger or the heat destroys the
cells. Never leave a pack in a charger, unless a peak charger, and you
are sure it isnt charging. Nicads are fully charged when voltage
drops and heats starts to build as a result. Peak chargers read either
temp, volt drop, or both.
Nicads are not the same as Lead Acid in charging and storage. Nicads
should be stored discharged , or 1.2 v per cell or just when your drill
slowes, it will be discharged. Running a pack dead, over discharging ,
will kill it or reverse cell polarity.
Lead acid boils electrolite when over charged, Nicads are Cooked when
overcharged.
Packs are best charged only once a day, to allow chemical
stabilisation. Never charge a hot or unrested pack.
I suspect Ryobi uses Sub C cells , not C a battery of less capacity.
Unless you have a peak charger watch pack temps, warm is Overcharged,
Any increase over room temp and the pack is peaked. I still use a 18 yr
old pack, not much life left in it, but it didnt die prematurely.
Tool makers charge Fully for battery replacement and its a high profit
item, There instructions seem biased to not informing customers of
correct procedures so they can rely on your future busiess.
Until drils have volt meters and electronics that stop a drill at low
voltage everyone will suffer shorter pack life. Most camcorders have
this feature as battery life is advertised , as is key. Why not tool
makers , Future profit.