Charger for lithium batteries. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Chargers, batteries, galvanic cells
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Cell phones, digital cameras, and some MP3,6 players use rechargeable lithium batteries with a nominal voltage of 3,7 ... XNUMX V. To charge such batteries, you must have an appropriate charger. Moreover, chargers designed for similar batteries, but different models of devices powered by them are not interchangeable (different sockets). Therefore, it is desirable to have a charger circuit so that the batteries can be charged outside of the powered device using some external DC source (eg lab unit).
In foreign amateur radio literature, a charger circuit based on the LTC4054 chip, shown in fig. 1. The HL1 LED indicates the charge, and the mode is set with the resistor R2. The voltage from the source is 4,5 ... 6,5 V. Everything would be fine, but, unfortunately, the acquisition of the LTC4054 chip causes certain difficulties.
Therefore, a charger was made on a more accessible element base (Fig. 2). On the A1 chip, a charging current stabilizer is made. The cascade on the transistor VT1 monitors the current in the circuit. The presence of the charging current is indicated by the LED HL1.
The charge current is about 100 mA.
Establishment of the scheme and operation of the device
Connect the power supply (5,5 ... 9 V). Without connecting the battery with resistor R8, set the output voltage to 4,2 V. Connect the battery. If the battery needs to be charged, the HL1 LED will light up. When charging is complete, the LED will turn off.
Author: Gorchuk N.
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