Small Battery Charger
1) Ni Cd Battery Charger
The nickel-cadmium battery is a popular type of rechargeable battery for portable electronics and toys using the metals nickel (Ni) and cadmium (Cd) as the active chemicals. They are sometimes used as a replacement for primary cells, such as heavy duty or alkaline, being available in many of the same sizes. It is commonly used in Mobile Phones, Rechargeable Torch, model airplanes etc.
Picture of Battery Charger Project
In our project we have used 2AA size Ni-Cd Battery which is commonly available and can be used in many appliances. This circuit can also recharge common dry cell battery for fewer times at certain level.
Nickel-cadmium cells have potential of 1.2 V. So Nickel-cadmium batteries come in multiple of 1.2 V for eg 2.4V, 3.6V, 4.8V etc but it maintains constant voltage throughout their service life and about 0.8–1 V when discharged.
The chemical reaction which occurs in a NiCd battery is:
2 NiO(OH) + Cd + 2 H2O ↔ 2 Ni(OH)2 + Cd(OH)2
Circuit diagram of Nickel Cadmium (Ni Cd) battery charger
Here is a simple and slow charger for better life of small Ni-Cd battery. Charge it for 6-12 hrs using this circuit.
Step Down Transformer 0-6 V
Resistance 10 Ω X2 Pcs
Disadvantage of basic charger circuit :
1) LED or ammeter as an Indicator shows how much approx current flowing according to its brightness. It does not confirm whether battery is fully charged or not.
2) No over charging protection may reduce battery life.
3) Uses low efficiency Transformer
Today (2021) , electronics technology have changed a lot. Most common battery used today is Li-Po Battery ( lithium polymer battery ) and Lithium Ion Battery. Advantage is of good life, light weight and a single cell is able to give 3.7Volt. Most common Lithium ion cell available in market is 18650. 18650 cell is of low cost and widely used in power bank, Laptop etc this cell is used for battery backup.
TP4056 1A Li-Ion Battery Charging Module
You can use this module for charging (3.7V) single cell. 18560, Mobile Battery, Lithium Ion or Lipo all can be charged. You have to give 5V input. Mobile charger can be directly connected. This module will offer max 1A charge current then cut off when finished.
The red LED indicates charging in progress, green LED indicates charging has finished (4.2V done).
This is low cost charging module everyone should buy it.
TP5100 Battery Charging Module
You can use this module for charging both single and double cell. When jumper is made short it will work for 2 cell (8.4V) charger else will give you 4.2V for single cell charging. Input voltage can be 5-15V. Output maximum current is 2A.
Charge status: full and unloaded blue lights, charging red.