Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
One way is to use a resistor which draws low enough current so that the discharge of a fully charged battery takes several hours. This way you can watch the terminal voltage with a VOM and stop it at 1.00 volts.
If you want to do it automatically, use a comparator to sense the 1.00 V and have a transistor on the low side of the resistor. The The transistor is connected to a flip flop to control the gate/base. The comparator flips the flip flop to the off state. Use a switch and resistor to flip it to the on state.
There are several automatic chargers/dischargers on the market that do this automatically, but they use fast charge and discharge which makes the battery hotter. This will reduce the number of charge/discharge cycles the battery will withstand.