The Amazing Secret in every Battery! (Fuel Gauge) EB#66

Published at : 23 Dec 2025

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In this video we will be having a look at my old Battery Level Indicator. Now it is super important to know the state of charge (SoC) of a battery. It basically tells us how much charge is left. I tried building an LED indicator for that in the past. But as time went on, this solution failed me and thus it is now finally time to learn about Fuel Gauges. These are the modern solution to keeping track of the SoC that everyone out there has already used before. Let's get started!

Websites that were shown in the video:
https://www.mouser.de/ProductDetail/Texas-Instruments/BQ34Z100PWR-G1?qs=igE0IiKpbrGE%2FNmDcdE48w%3D%3D
https://www.ti.com/product-category/battery-management-ics/battery-fuel-gauges/overview.html
https://www.mouser.de/ProductDetail/Texas-Instruments/BQ41Z50RSNR?qs=2FehpBK1j95h5MRSV2e3rA%3D%3D
https://www.mouser.de/ProductDetail/Texas-Instruments/BQ27441DRZR-G1B?qs=vvk%2Fphg2gmNVugTODHzqlg%3D%3D
https://www.mouser.de/ProductDetail/Soldered/333065?qs=QpmGXVUTftEyMUtYzbP%2FbA%3D%3D
https://github.com/SolderedElectronics/Soldered-BQ27441-Battery-Fuel-Gauge-Arduino-Library
https://github.com/sparkfun/SparkFun_BQ27441_Arduino_Library?utm_source=chatgpt.com

0:00 Old Battery Level Indicator Problem
0:57 Intro
1:28 How the old Solution works
2:41 Don't trust the Voltage!
4:01 Fuel Gauge Basics
5:19 DIY Fuel Gauge?
5:52 Finding a fitting IC
7:00 BQ27441 Fuel Gauge!
7:37 Testing!
10:19 Verdict