Appointment: charging of any types of accumulators in the specified range.
For example, they can charge all types of screwdriver batteries.
Charging starts when you press the Start button. The indicator lights up. Upon completion of charging, the relay unit automatically disconnects the battery from the charger. The indicator goes off.
Charging voltage is set by resistor R3 on a DC-DC buck converter (see charger diagram). The maximum charging current is set by the resistor R1. Resistor R2 sets the device shutdown threshold (end of charging).
24v 1a power supply module - https://www.ebay.com/itm/AC-DC-5-12-15-24V-Switching-Power-Supply-Module-
Regulator-Voltage-Switch-Board / 142915009965
DC-DC Buck Converter LM2596 - https://www.ebay.com/itm/LM2596-DC-DC-Step-down-Adjustable-CC-CV-
Power-Supply-Module-Converter-LED-driver / 191673918658
Isolated Relay Module - https://www.ebay.com/itm/1CH-2CH-4CH-Relay-Module-Board-With-Optocoupler-
H-L-Level-Triger-5-9-12-24V / 123484927241
If you need a charger 1.5 - 21V 0.1-5A, then you need to use these blocks instead of the above.
24v 5a power supply module - https://www.ebay.com/itm/AC-100-240V-to-DC-24V-4A-6A-switching-power-supply-
module-AC-DC-S8T4 / 302752973085
DC-DC buck converter - https://www.ebay.com/itm/XL4015-5A-DC-DC-Step-Down-Buck-Converter-Module-Power-Supply-LED-Lithium-Charger/311820844395