Alkaline Battery Fuel Guage

Chandra214

We want to implement a fuel guage 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”
http://www.ppgee.ufmg.br/parecer/doc...JNPIM00124.PDF