Maximizing Battery Life: Using Load Droop to Detect Charge Level

Click For Summary

Discussion Overview

The discussion revolves around methods for detecting the charge level of batteries, particularly in the context of building a power bank. Participants explore various techniques, including the use of integrated circuits (ICs), voltage measurements, and load droop analysis.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Akmalidin Alimov seeks an IC solution for voltage level detection in a power bank project, indicating familiarity with transistors and op-amps.
  • One participant notes that battery voltage may not reliably indicate state of charge due to variations with age, temperature, and technology, suggesting a search for battery monitor ICs.
  • Another participant mentions that battery fuel gauge chips are available and that a microcontroller (MCU) with an analog-to-digital converter (ADC) could also be used for this purpose, highlighting the variability of battery voltage under different conditions.
  • It is pointed out that open circuit or light load voltage can be effective for gauging state of charge for certain battery types, such as lithium-ion and lead-acid, but may not be as reliable for others like alkaline batteries.
  • A method involving momentarily connecting a load to measure voltage droop is proposed as a way to assess the state of charge, with the suggestion that the amount of droop could indicate a full charge.

Areas of Agreement / Disagreement

Participants express differing views on the reliability of battery voltage as an indicator of charge level, with some advocating for IC solutions and others suggesting alternative methods like load droop measurement. The discussion remains unresolved regarding the best approach to accurately determine battery charge levels.

Contextual Notes

Participants acknowledge various factors affecting battery voltage, such as internal resistance, temperature, and current draw, which may complicate accurate charge level detection.

Akmalidin
Messages
69
Reaction score
6
Hello,

I am building a power bank myself and want to set put detector that determines the voltage level and indicates it in LED (4 LED are planned to be used). I know how to make it with transistors and op amp. But I was wandering if there is any IC chip that does it?

Thank you,
Akmalidin Alimov
 
Engineering news on Phys.org
The voltage of a battery isn't always a good indication of the state of charge. Battery voltage also varies with age and temperature and technology.

Google battery monitor ic. Companies like Maxim have a range. Might be easier to buy a ready built module off ebay
 
  • Like
Likes   Reactions: davenn
Chips designed to provide battery state of charge information are typically listed as battery fuel gauges under supplier categories. Though you can do what you want pretty simply with an MCU using its ADC. For some battery types open circuit or light load voltage can provide a good gauge for state of charge. For other battery types It doesn't work as well. Lithium-ion and lead-acid can be gauged well enough using open circuit voltage as long as temperature is not extreme. Primary batteries such as alkaline can also be gauged that way. Problem is battery voltage drops under load depending on current draw and battery internal resistance (which can vary due to temperature, battery wear, and state of charge). You may need a mechanism to deal with those factors depending on how accurate your gauge needs to be.
 
Another way to determine the state of charge of batteries is to momentarily connect a load representing the maximum load you expect the battery to see and measure the amount of droop. As the battery charges, the amount of droop will decrease. You would need to decide the amount of droop that would represent a full charge.
 

Similar threads

  • · Replies 26 ·
Replies
26
Views
5K
Replies
1
Views
4K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 17 ·
Replies
17
Views
8K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 13 ·
Replies
13
Views
10K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 1 ·
Replies
1
Views
6K