Simple nicad battery charger and discharger circuit

Do you use a 9V battery? Many projects use it as source energy. The nicad battery is good commonly used. We can recharge them when dies. If you do not have a battery charger.

I recommend this is the simple nicad battery charger circuit. It is suitable for beginners. But still works great. Charging batteries are commonly used in the circuit because it’s cheap.


Because we use a simple little device really. The Ni-cad battery charger circuit can be used with the battery will charge with 4.8 Volt current 800mA using it for about five hours, “which serves R1 limit the current flow. To the Ni-cad battery charger circuit where the R2 and LED1 are told that the state of the battery charger that fully or to show that if LED1 on battery power is not full.

Simple 9-volts NiMH-Nicd battery charger circuit

Simple 9-volts NiHM-Nicd battery charger-circuit

9-volts NiHM-Nicd battery charger circuit is easy.

Here is Simple 9-volts NiMH-Nicd battery charger circuit as Figure 2. Input is 12-volts from the normal DC adapter and takes the 9-volt battery to the Snap connector.

Simple 9-volts NiHM-Nicd battery charger

Real simple project. What is more? Not only that we should learn.

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How to discharge Ni-Cd battery

I am going to show you a discharge Ni-cd Battery circuit. Why should you use this?

Ni-Cad battery has advantages that rechargeable to reuse again. And cheaper than other types of rechargeable batteries like Ni-HM battery.

I love NiCd batteries. Because they are mains 4 reasons:

  • Hard to damage more durable than lead-acid or lithium batteries.
  • Far more tolerant towards long deep discharge cycles.
  • It can perform well under tough conditions.
  • Have high energy like with alkaline batteries (cannot recharge).

But they have an important disadvantage is a memory effect. Before charging this battery. It needs to have power is zero only.

how to Discharge Nicad battery

If you charge it while little energy remaining. It will cause the memory effect status.

There are 2 disadvantages: It will remember that voltage or energy level. Resulting in not being able to release the maximum energy. And importantly, the lifetime of this type of battery is shorter, too.

Read Also: Simple NiMH NiCd Battery Charger circuit

A good solution is using the Discharge Nicd battery circuit at all times. Before charging with a normal battery charger.

Prohibition: Do not cause the battery to short-circuit. It will damage the battery.

We have 2 circuits to do:

Simple circuit with relay

This is simple ni cad battery discharge for 6V (1.2Vx4). This circuit will help increase its lifetimes of more.

How it works

When we connect the batteries 6V(1.2V in series) to discharge.  Both diodes D1 and D2 in series, they will detect a voltage of the battery.

Recommended: Simple 1.2V AA battery Solar charger circuit

If the battery has a voltage more 1.4V. It makes RY1 run. A contact switch from NC into NO. It makes L1 flow up until the voltage is lower down.  Adjust VR1 to stop working to contact NO to NC. Then, the L1 goes out. It finished the discharged process.

simple discharge ni cad battery using Relay and lamp

Discharge Ni-Cd battery in many voltages

We can use this circuit for many levels of the battery from 3V to 15V.

discharge Ni-cd Battery

This circuit is used to discharge the battery at a voltage bias to Q1 adjusted using VR1 serves volt bias to the base pin of Q1 is appropriate to bring the battery if the battery has voltage remaining Lamp. Light up until the battery runs out Lamp will gradually vanish if there is no battery power remaining lamp will not start.

Parts you will need

VR1: Potentiometer 1K Q1: TIP3055, NPN transistor L1: 12V 10W light bulbs

Caution: In use, if possible, Q1 should be mouth attached to the heat sink, too.

CR: image by StonyCreek

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7 thoughts on “Simple nicad battery charger and discharger circuit”

  1. great project, battery charging with 9volt but would like to know the volt of battery charging when the led comes on. on the note, i am new to electronics just wondering how LED works if connected to positive rail only. so far charging 16mA is that right.

    Thanks in advance

  2. Hello: Need to build a quick field charger for three to four 1/3rd AA nicads. I use these small batteries to power 30 inch or so free flight balsa stick and tissue airplanes running small brushed motors like the Hi-Line Mini six. The charger that a friend made was stolen. That one used a DC bulb of unknown size as a current limiter. I’m good at soldering and like to build stuff even though electronics is my weakest subject. Much thanks, Tom Baron

    • Hello thomas a.baron,
      I like a AA nicads battery too. It can be recharged many times. I use it for shavers, remote controls, etc.
      Most importantly, it’s cheap. If the battery size is 600mAh. Use a low charging current. This circuit also works. Even charge it for a long time (forgot). The battery is not hot.

      Have a good day.


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