A simple indicator of the discharge of Li-ion batteries
How tightly did Li-ion batteries come into our lives? The fact that they are used in almost all microprocessor electronics is already the norm. So radio amateurs have long taken them into service and used in their homemade products. I contribute to this significant advantages of Li-ion batteries, such as small size, large capacity, a large selection of versions of different capacities and forms.The most common battery has a mark of 18650, its voltage is 3.7 V. For which I will have a discharge indicator. Probably, you should not tell , how harmful to the battery crane is their low discharge. And for batteries of all varieties. Proper operation of batteries will prolong their life several times and save you money.The threshold is set by resistors R2, R3. Instead, you can solder a single variable to allow adjustment and reduce the number of elements. Soviet transistors can be replaced by BC237, BC238, BC317 (КТ3102) and BC556, BC557 (КТ3107).The circuit can be assembled on a board or mounted mounting. Put on a heat shrink tube and blow a heat gun. Stick on double-sided tape to the back of the case. I personally installed this board in a screwdriver and now I don’t drive its batteries to a critical level. You can also connect a buzzer (squeaker) parallel to a resistor with a LED, and then you will know for sure about critical thresholds.