simplest smf automotive battery charger

Posted on Feb 6, 2014

A very simple battery charger circuit is described in this article, which uses just a single transistor for the voltage detection as well as for automatically disconnecting the battery from the supply when it gets fully charged. This adjustment becomes the high voltage trip point of the circuit and is used to switch OFF the charging voltage to

Click here to download the full size of the above Circuit.

the battery when it gets fully charged or its voltage reaches around 14 volts. Typically a general purpose transistor like the one which is shown (BC547) when adjusted to switch ON at 14 volts may have the lower threshold of around 10 volts, when it might get just switched OFF. The lower threshold of 10 volts is dangerously low and we cannot wait for the circuit to restart the charging process until the battery voltage falls to this dangerous 10 volts level. Therefore to eliminate this issue the circuit needed to somehow reduce the hysteresis level. This is done by introducing a couple of diodes at the emitter of the transistor. By inserting the two diodes in series with the emitter of the transistor, we force the transistor to switch off 1. 4 V earlier than its normal specified limit of 10 volts. Therefore now the lower operating threshold of the circuit becomes 10 + 1. 4 = 11. 4 volts, which may be considered just OK for the battery and for the automatic restart of the charging process. Having both the thresholds updated as per the standard charging requirements, we now have an automatic automotive battery charger that`s not only cheap to build but also smart enough to take care of the battery charge conditions very efficiently.

Visit page

Leave Comment

characters left:

Related Circuits

Ultrasonic sound producer(insect repellent)

As we know many kinds of insects have their tendency to hear ultrasonic sound(which cause them irritation), this project is very useful to swept away those insects like mosquito cockroach etc.

PIC 18 Explorer Board LCD Example Code With SPI Library

Learn to use the LCD display on your pic 18 explorer board with the spi library. The spi library will be used to easily display characters on the LCD. You will also learn how io expanders work.

cellphone operated land rover

I know the general rule of world that reading makes man ready, writing makes man everyday but practice makes man perfect. Only theoretical knowledge is not enough for an E. C (Electronics and...

RC5 Protocol Decoding with 8051

Infrared light is electromagnetic radiation with longer wavelengths than those of visible light. Infrared light is used in industrial, scientific, and medical applications. Most of the remote...

Digital Clock Using Microcontroller 89C52/89S52

Are you a beginner in micro controller projects and are you stuck where to start from if yes, then this is one of the simplest mini projects that you can start from. This mini project will give you...

Password(code) Based Digital Locking System Using Microcontroller 89C52/89S52

entering of the password, the application as in this case "led" will glow. In this Digital locking system project you will learn more about interfacing keypad and 16x2 LCD to your micro controller...

Shifter(Bit Shifter) in Computers and its

EL Lamp Driver Using HV832MG

An EL lamp is a solid state, low power, uniform area light source. Because of its thin pro ¬le (as thin as 0. 3 mm) and the fact that it can be built into almost any size and shape, EL lamps are...

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
Ultrasonic distance finder circuit

The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Simple Metal detector circuit with CD4030

Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Fully automatic watering circuit for flower pots

Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
Simple deep searching metal detector circuit

The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
Sub-Harmonic Bass Converter for Electric Guitars

The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
Echo Depth Sounding Sonar for Boats

In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
100W HiFi Audio Amplifier Circuit

This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
Plant-Pot Water Level Indicator Circuit

A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....

Create NOW your QR MENU for your Restaurant / Hotel / Bar / Caffe,

Comprehensive ordering/paying features. fully personalized to suit your Business.

Update Anytime! Easy and Simple!

Popular Circuits

Centrifugal fish autofeeder

This easy as well as cheap but effective device is mainly intended for your ease to leave your...

digital thermometer schematics

This digital thermometer circuit diagram uses a common 1N4148 diode as the temperature sensor....

Infra-red Level Detectors

This circuit is useful in liquids level or proximity detection. It operates detecting the...

RXTX V6.3 TX Mixer

TX OpAmps TX Mixer (QSE) PTT RX Switching PA/Filters External Connectons Comments Revisions...

A read-only phase sequence indicator circuit

As can be seen from the three-phase voltage waveform diagram [Figure 2- 76 (a)] When one of the...

A three-alarm phase circuits

As shown in (a), KAi, KA2, KA3 intermediate relay, connected to the outlet end of the...

Hybrid power amplifier 01

CD4069 unit structure of FIG. 2-5 (a) shown below, it is composed of two abutment surfaces into...

Automatic anti-frost crop controller circuit diagram

Circuit works The automatic anti-frost crop controller circuit consists of electric contact...