Recommended charging and discharging methods vary strongly depending on battery chemistry, but unless the battery contains its own battery management circuitry (i.e. like most lithium ion consumer batteries) the proper way to charge them for maximum life and capacity maintenance shouldn't vary much between manufacturers for the same battery chemistry.
I've never seen a Ni-Cd battery that was anything other than "maintenance free"- the only batteries requiring that kind of maintenance (i.e. maintaining fluids) are lead acid. The only maintenance that a Ni-Cd needs is a controlled charge and avoidance of over-discharge. Over-discharge is the real killer for most multi-cell batteries.
Constant potential charging is tolerated rather than truly acceptable for any battery, because if you select that constant potential too low you won't get a truly full charge, and if you set it high enough to achieve a full charge but fail to shut it off at the end of charge, you will over-charge and ultimately do damage to the battery. To my knowledge, that's the case with ANY battery chemistry, but the voltage sensitivity, the loss of charge due to setting the constant voltage too low, and the severity and nature of damage due to over-charging, varies greatly from battery chemistry to battery chemistry. For some chemistries, it's no real problem at all- within limits of course.
