Site icon Circuit Ideas for You

Advanced Ni-Cd Battery Fast Charging Circuit

Ni-Cd batteries are used in many devices and they have high energy and can recharge.

But normal charging is slow and is not good, so it can harm battery life.

To fix this Advanced Ni-Cd Battery Fast Charging Circuit using MAX712 chip is made.

This charger charges fast, safe and works well for Ni-Cd.

This article will explain circuit design, building, working and calculations behind it.

Circuit Working:

Parts List:

Component TypeValue/SpecificationQuantity
Resistors (All resistors are 1/4 watt unless specified)22k1
68k1
220Ω1
470Ω1
150Ω1
1Ω 1W1
CapacitorsCeramic 0.01µF1
Ceramic 0.1µF1
Electrolytic 1µF 25V1
Electrolytic 1000µF 25V1
SemiconductorsIC MAX7121
PNP Transistor 2N29071
Diode 1N40075
LED 5mm, 20mA1
Ni-Cd Battery2

The fast Ni-Cd charger circuit has some main parts working together.

It uses a bridge rectifier, voltage regulator, MAX712 chip and power transistor.

AC input from 6V to 9V comes in and turns into DC which is good for charging Ni-Cd batteries.

First diodes from D2 to D5 a bridge rectifier change AC to DC.

Then capacitor C4 1000µF smooths the DC and removes bumps.

MAX712 IC chip controls charging and checks voltage and current by stops overcharging.

Charging time and working depend on resistor R1 and capacitor C2.

LED1 shows if battery is charging.

Power transistor Q1 controls charging current.

Resistors R5 and R6 help manage current to battery pack.

Formulas with Calculations:

To make our own Ni-Cd fast charger then we can use these formulas:

Charging Current (Icharge):

Icharge = Vout / R

where,

Charging Time (Tcharge):

Tcharge = (1.4 × Cbattery) / Icharge

where,

Example:

Battery = 1000mAh and Icharge = 500mA

Tcharge = (1.4 × 1000) / 500 = 2.8 hours

Power Loss in Resistor (P):

P = I² × R

Example:

I = 0.5A, R = 1Ω

P = (0.5)² × 1 = 0.25W

Use a 1W resistor for safety.

How to Build:

To build a Advanced Ni-Cd Battery Fast Charging Circuit following steps need to be followed for connections of the circuit:

Conclusion:

This Advanced Ni-Cd Battery Fast Charging Circuit charges batteries fast and safe.

There is no long wait as the battery lasts longer.

We can change charge speed and time for different battery sizes.

It is great for hobby people, DIY lovers and for backup power needs.

References:

MAX712 Linear-Mode Evaluation Kit

Exit mobile version