NiMh and NiCd Battery Charger Circuit

NiMh and NiCd Battery Charger Circuit

Circuit Description

This automatic NiCd charger for 9V NiCd batteries is using 555 timer
properties and is very easy to build. Why is an automatic 9 volts NiCd
battery charger? Because you can leave the battery for charging as much
as you like: it will be always completely charged and ready for use when
is needed. It wont be overcharged and it will not discharge. With the
values presented in the circuit diagram, the battery charger NiCd
circuit is suitable for 6V and 9V batteries.

9 volt types with 6 and 7 cells are charging with 20mA; P1 must be
adjusted so that the NiCd charger disconnects after 14 hours. Window
inferior level is set at 1V below this value with P2. 5V battery type
with 4 or 5 cells are charged at 55mA. Again, with P1 adjust the NiCd
charger circuit so it disconnects after 14 hours. Window inferior level
must be set at 0.8V below this value.

Circuit diagram:

Circuit

Parts:

  • P1 = 50K
  • P2 = 50K
  • R1 = 820R
  • R2 = 820R
  • R3 = 1K
  • R4 = 10K
  • R5 = 10K
  • R6 = 100R
  • D1 = 4.7V Zener
  • D2 = 1N4001
  • D4 = 1N4148
  • D5 = B40C1500 Diode Bridge
  • C1 = 220uF – 25V
  • Q1 = BC547B
  • IC = 555
  • B1 = 9V Ni-Cad Battery

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