I bought a budget screwdriver "Dyold". Charging: Transformer, diode bridge and 2 LEDs; it charges like an iron when charging.
I decided to collect a charger for my new friend ...
Internet to help, first theory.
Ni-Cd batteries have a large self-discharge. All Ni-Cd batteries have a memory effect, i.e. if they are not discharged to the end, then they lose their capacity.
The number of charge-discharge cycles for any battery is limited.
That is, you need a charge discharge charge. For the discharge, I installed a cooler from a PC, slowly but surely.
The discharge limiter was made from the board from the phone’s battery:
Charge limiter:
A source:
It turned out something like this:
The case from the power supply of the Soviet computer (5 volts).
Transformer from the standard memory
Bottom line: Set the response (empirically) max-15 v, min-10v.