Engineers Garage

  • Electronic Projects & Tutorials
    • Electronic Projects
      • Arduino Projects
      • AVR
      • Raspberry pi
      • ESP8266
      • BeagleBone
      • 8051 Microcontroller
      • ARM
      • PIC Microcontroller
      • STM32
    • Tutorials
      • Audio Electronics
      • Battery Management
      • Brainwave
      • Electric Vehicles
      • EMI/EMC/RFI
      • Hardware Filters
      • IoT tutorials
      • Power Tutorials
      • Python
      • Sensors
      • USB
      • VHDL
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Product News
    • Business News
    • Company/Start-up News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • DigiKey Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • Learn
    • eBooks/Tech Tips
    • Design Guides
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • Digital Issues
    • EE Training Days
    • LEAP Awards
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Engineering Diversity & Inclusion
    • DesignFast
  • Guest Post Guidelines
  • Advertise
  • Subscribe

Battery Monitor

By D.Mohankumar April 21, 2008

 

Irrespective of their applications, a good power supply is always needed to propagate electronic circuits. Hence, it becomes a priority to keep record of power supply, especially when the circuits and their corresponding gadgets are battery powered. Systems such as household power supply inverters, emergency lighting units are placed in this category where dependence on battery is always there. So, the user always needs to keep an eye on the battery levels so that these systems do not run out of power. 
Battery Levels

Most of the Emergency lamps do not have low battery indicator which is essential to indicate the deep discharge of battery. So if the Emergency lamp is switched on continuously, battery will discharge deeply and causes 2 problems. 1. Ends of the fluorescent tube will turns black and fails. 2. If the battery is discharged fully, it may develop memory effect and will not accept full charge. To avoid these problems, the battery should not be allowed to discharge below its 50% efficiency. This simple add on circuit will give a visual indication when the battery enters in to the deep discharge stage.

 

6v battery

A few components are sufficient to make this battery level indicator. It can be connected along with the existing circuit board.
 
When the power is switched on and if the battery is holding 6 volts, both Red and Green LEDs light. Red LED indicates that the emergency lamp is on. Green LED indicates that the battery voltage is above 4.5 volts (Preset level). When the battery voltage drops below 4.5 volts, Green LED turns off indicating that the battery is entering into the deep discharge stage. 

 

When the power is switched on, Red LED lights and current passes through VR and the wiper of VR is set so as to forward bias T1 at 4.5 volts. So till the voltage drops to 4.5 volts, T1 conducts and Green LED lights.
How to set
1. Fully charge the emergency lamp battery. The terminal voltage should be 6.8 volts in the fully charged state.
2. Switch on the emergency lamp and monitor the battery voltage using a multimeter.
3. Fix the low voltage level. Say 4 or 4.5 volts. Keep the lamp switched on till the terminal voltage of the battery drops to the desired low voltage.
4. Switch off the lamp and check the voltage. If it is the desired low voltage level, say 4.5 volts, slowly adjust VR till Green LED turns off.
5. Charge the battery again. When the voltage level rises, Green LED turns on.

 

 

 

Circuit Diagrams

battery-saver


Filed Under: Electronic Projects

 

Next Article

← Previous Article
Next Article →

Questions related to this article?
👉Ask and discuss on Electro-Tech-Online.com and EDAboard.com forums.



Tell Us What You Think!! Cancel reply

You must be logged in to post a comment.

EE TECH TOOLBOX

“ee
Tech Toolbox: 5G Technology
This Tech Toolbox covers the basics of 5G technology plus a story about how engineers designed and built a prototype DSL router mostly from old cellphone parts. Download this first 5G/wired/wireless communications Tech Toolbox to learn more!

EE Learning Center

EE Learning Center
“engineers
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for EE professionals.

HAVE A QUESTION?

Have a technical question about an article or other engineering questions? Check out our engineering forums EDABoard.com and Electro-Tech-Online.com where you can get those questions asked and answered by your peers!


RSS EDABOARD.com Discussions

  • Finding past posts on edaboard?
  • Industrial Relay Board Design for Motorcycle Use
  • I think i have devised a new type of "super_transformer" for the Electricity grid?
  • What is the purpose of this relay?
  • mosfet driver problem in regeneration mode

RSS Electro-Tech-Online.com Discussions

  • Pic18f25q10 osccon1 settings swordfish basic
  • Sump pit water alarm - Kicad 9
  • Anyone jumped from Easyeda std to Easyeda pro?
  • turbo jet fan - feedback appreciated.
  • More fun with ws2812 this time XC8 and CLC

Featured – LoRa/LoRaWan Series

  • What is the LoRaWAN network and how does it work?
  • Understanding LoRa architecture: nodes, gateways, and servers
  • Revolutionizing RF: LoRa applications and advantages
  • How to build a LoRa gateway using Raspberry Pi
  • How LoRa enables long-range communication
  • How communication works between two LoRa end-node devices

Recent Articles

  • How IoT network topologies work
  • The top five AI startups to watch in 2025
  • STMicroelectronics unveils SoC based on secure MCU
  • Nexperia’s 48 V ESD diodes support higher data rates with ultra-low capacitance design
  • Taoglas releases Patriot antenna with 18 integrated elements covering 600 to 6000 MHz

EE ENGINEERING TRAINING DAYS

engineering

Submit a Guest Post

submit a guest post
Engineers Garage
  • Analog IC TIps
  • Connector Tips
  • Battery Power Tips
  • DesignFast
  • EDABoard Forums
  • EE World Online
  • Electro-Tech-Online Forums
  • EV Engineering
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips
  • 5G Technology World
  • Subscribe to our newsletter
  • About Us
  • Contact Us
  • Advertise

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy

Search Engineers Garage

  • Electronic Projects & Tutorials
    • Electronic Projects
      • Arduino Projects
      • AVR
      • Raspberry pi
      • ESP8266
      • BeagleBone
      • 8051 Microcontroller
      • ARM
      • PIC Microcontroller
      • STM32
    • Tutorials
      • Audio Electronics
      • Battery Management
      • Brainwave
      • Electric Vehicles
      • EMI/EMC/RFI
      • Hardware Filters
      • IoT tutorials
      • Power Tutorials
      • Python
      • Sensors
      • USB
      • VHDL
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Product News
    • Business News
    • Company/Start-up News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • DigiKey Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • Learn
    • eBooks/Tech Tips
    • Design Guides
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • Digital Issues
    • EE Training Days
    • LEAP Awards
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Engineering Diversity & Inclusion
    • DesignFast
  • Guest Post Guidelines
  • Advertise
  • Subscribe