LITHIUM BATTERY CHARGER CIRCUIT SCHEMATIC DIAGRAM

LITHIUM BATTERY CHARGER CIRCUIT SCHEMATIC DIAGRAM

The charging system shown is designed for multi-cell battery pack of 2 to 6 series connected cell or series/paralel arrangements. It is essential that all cells assembled in the pack are at an identical state-of-charge (voltage) before charging. the maximum upper cut-off voltage is 15.6V (6×2.6V). ICL7665 is a voltage monitor with dual over/undervoltage detection.

ADJUSTABLE REGULATED BATTERY CHARGER CIRCUIT SCHEMATIC DIAGRAM

Power transistors Q1 and Q2 are connected as series regulators to control the battery charger ‘s output voltage and charge-current rate. An LM-317 adjustable voltage regulator supplies the drive signal to the bases of power transistor Q1 and Q2. Potensiometer R9 sets the output-voltage level. A current sampling resistor, R8 (a 0.1 ohm/5W unit), is connected between the negative output lead and circuit ground. For each amp of charging current that flows through R8, a 100mV output is developed across it. The voltage developed across R8 is fed to one input of comparator U3. The other input of the comparator is connected to variable resistor R10.

As the charging voltage across the battery begins to drop, the current through R8 decrease. Then the voltage feeding pin 5 of U3 decreases, and the comparator output follows, turning Q3 back off, which completes the signal’s circular path to regulate the battery’s charging current.

CIRCUIT NICD - NIMH BATTERY CHARGER SCHEMATIC DIAGRAM

NiCd – NiMH Battery Charger circuit diagram

Note:

I is 1/10 of the battery’s charging capacity. For example if battery has a rated capacity of 1700mA then ?=170.
The input voltage must be at least 3 times the battery’s voltage. For example an input voltage of 25V can charge a 8,4V (9V) battery.