Those are all nicads
Nicad packs can be taken down to 0 volts, think twice about doing that with Nimh. I use a smart tray from Promatch that takes them down to .7 which is a little low, but they are all exactly the same. I also have some itegys tray with bulbs. I unscrew the bulb when it goes out so the rest of the cells can catch up.
Just my $.02
David Root