How Can You Measure the Remaining Charge in Alkaline Batteries?

[Chandra214]

We want to implement a fuel gauge into one of our field testing equipment.
The batteries are Alkaline type. Is there any proven method to calculate the amount of usable charge left?
Thanks in Advance
Prathap Chandra

 

[Chandra214]

We have come about with an approach to have a constant current load on the battery while the voltage is measured by an ADC to estimate the remaining battery charge.

 

[vk6kro]

What seems to be standard in commercial equipment is to measure the voltage when the equipment stops working, then scale the difference between this voltage and the new battery voltage and express it as a percentage.

Pretty rough, but OK if the battery decline is linear.

Or, you could measure voltage vs time by running the equipment continuously until it stops working and take periodic voltage measurements. Then examine the graph of this and see if you can make up a look-up table to estimate time left in the battery from its battery voltage.

One problem is that battery voltage varies with temperature, so these methods might fail if the temperature varies a lot.

 

[Bobbywhy]

There are several methods of determining the State of Charge (SOC) of an alkaline battery, such as Direct Measurement, Voltage Based SOC Estimation, and Current Based SOC Estimation - (Coulomb Counting). These are discussed at the below website. Also find a discussion of Consumer Battery Condition Indicators.
http://www.mpoweruk.com/soc.htm

You may find this to be useful:
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 58, NO. 6, JUNE 2009
“Remaining Capacity Measurement and Analysis of Alkaline Batteries for Wireless Sensor Nodes”
www.ppgee.ufmg.br/parecer/docs/OHUHOJNPIM00124.PDF

 

[alphysicist]

Dear Prathap Chandra,

Thank you for your inquiry about implementing a fuel gauge for your field testing equipment that uses alkaline batteries. I can suggest a few methods for calculating the amount of usable charge left in your batteries.

1. Voltage-based measurement: One way to estimate the remaining charge in alkaline batteries is to measure their voltage. As the battery discharges, its voltage decreases gradually. You can use a multimeter to measure the voltage and compare it to the manufacturer's specifications to determine the remaining charge.

2. Time-based calculation: Another approach is to calculate the remaining charge based on the time the battery has been in use. You can keep track of the battery usage time and compare it to the expected lifespan of the battery to estimate the remaining charge.

3. Impedance measurement: The internal resistance of a battery increases as it discharges. You can use an impedance meter to measure the internal resistance of the battery and estimate the remaining charge based on the change in resistance.

4. Smart battery technology: Some modern batteries come with built-in microchips that monitor the battery's charge and provide real-time information on the remaining capacity. These batteries are more expensive but offer more accurate and reliable readings.

It is important to note that these methods can provide estimates of the remaining charge and may not be 100% accurate. Also, the accuracy of these methods may vary depending on factors such as battery age, temperature, and usage patterns.

I recommend conducting some experiments to determine the most suitable method for your specific equipment and batteries. You can also refer to the manufacturer's guidelines for more information on calculating the remaining charge in your alkaline batteries.

I hope this information helps in your quest to implement a fuel gauge for your field testing equipment. Good luck with your project.

Best regards,