Parallel automatic charger circuit diagram

Many chargers use series charging. This type of charger has a common feature. It is necessary to ensure that the discharge status of each battery is consistent, that is, to ensure that the remaining power of each battery is equal. Otherwise, some batteries will not be fully charged, and some batteries will not be fully charged. It has been overcharged. Therefore, this is a simple parallel automatic charger , which has been used for half a year and has achieved good results. It is here provided for reference by interesting readers.

This charger is made of ordinary components, and the principle is as shown in the figure. The charger has the characteristics of constant current charging, automatic switching to trickle charging after full charge, and selectable charging current .

Transistors VT2, VT4, VT6, VT8 and their related components constitute a constant current circuit. The charging current is set to two levels: 50mA and 120mA; when the switch S is closed, the charging current is 50mA; when S is opened, the charging current is 120mA. Transistors VT1, VT3, VT5, VT7 and their related components constitute a full state monitoring circuit. The potentiometer RP is used to set the full voltage. For nickel-cadmium batteries, it is set between 2.05V and 2.1V. The battery full voltage setting can also be performed by inserting a newly fully charged battery.

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The method is: put in the battery, close switch S, adjust RP so that the indicator lights LED1~LED4 are on, let the battery charge for another 2~3 minutes, and then adjust RP until the indicator light just goes out. After being fully charged, the battery enters the trickle current maintenance state, and the trickle current is set to about 9mA through resistors R4, R7, R10, and R13.