If you have owned any kind of battery-powered device in the last decade (maybe more), you have probably glanced at and asked yourself, "how many bars you have left." In other words, your were peeking at your battery fuel gauge.  It's one of those devices that you can take for granted (for years), without stopping to think that someone designed that battery fuel gauge. So, my question is, are you ready to design a battery fuel gauge?

 

You maybe be a maker and don't feel the need to design a battery fuel gauge. Maybe not. I fiound a battery fuel gauge project on DF Robot featuring the Raspberry Pi 3. Whether you are a hobbyist or a professional, you may need to either buy one or design a battery fuel gauge yourself, so it's something good to know about.

 

Battery fuel gauges indicate how much energy (the juice) is left in a battery. They "monitor" the voltage, charge/discharge current and battery temperature, and estimate the battery’s state-of-charge. In general, there are three types of battery fuel gauges: Open Circuit Voltage, Coulomb Counter, and Dynamic.

 

Sometimes battery fuel gauges are called battery monitors (as I did in the above paragraph). But that isn't necessarily true. A battery monitor reads out battery parameters. Without a gauging algorithm, a battery monitor usually can't estimate state-of-charge.

 

Battery fuel gauges are simple devices, despite the fact that estimating the state-of-charge can depend on a variety of factors.  Battery fuel gauges have become sophisticated. They have advanced to the point of integrating most of their circuitry into an IC package, which could include regulated power supply, an ADC, an MCU, sensing resistors, etc. Fuel gauging ICs are also capable of correcting measurements due to variations in temperature and/or voltage.

 

To learn more about battery fuel gauging ICs, I would recommend you check out our currently enrolling roadtest that lets you play around with battery fuel gauging ICs. If interested, go here: https://www.element14.com/community/roadTests/2030/l/MAX17260GEVKIT#-Fuel-Gauge-EVM