Go to
www.energizer.com "Technical Details" to see detailed datasheets and Applications Manuals for every battery they sell.
Their Ni-MH cells are fully charged at 1.4V each when charged at a low current and are 1.5V to 1.6V when charged at a high current.
They get hot and have a very high internal pressure when overcharged and might "vent" gasses and chemicals.
Their trickle charge current is recommended to be low at only 1/40C.
My Energizer charger for their 2500mAh Ni-MH AA cells charges them at about 500mA for 6 hours. It is simply a stupid timer. It severely over-charges cells that already have some charge. A good charger circuit will detect when the cells are fully charged then shut off or switch to a low trickle charge.
My sound Level indicator project (20 bright LEDs in a VU meter) is usually powered from a 8.5V/350mA wall-wart AC-DC adapter which also continuously trickle charges its 8.4V Ni-MH battery (7 cells).
My charger circuit is the voltage limit of the wall-wart (about 9.8V) and a current-limiting resistor. It has worked perfectly for years. The battery is slightly warm when trickle-charging. There is no switch, the battery powers the circuit when the mains electricity is not present.