Mobile power is easy to take for granted until a supposedly high-power charger underperforms, a USB-C cable becomes the bottleneck, or a battery-powered project shuts down at exactly the wrong moment. In Elektor Lab Talk #49, Brian Tristam Williams, Jens Nickel, and Saad Imtiaz will examine the practical electronics behind USB-C charging, portable power, batteries, and the numbers printed on charger housings. The USB Power Delivery specification enables a source and device to negotiate suitable voltage and current levels, with current Extended Power Range modes supporting up to 240 W. The charger, cable, connector, and load must all support the required power, however.

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Elektor Lab Talk #49: Mobile Power, USB-C, and Batteries

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Mobile Power Beyond the Label

A large wattage printed on a charger indicates its maximum capability, not what every connected device will receive. The available power may depend on the supported USB Power Delivery profiles, the rating and electronic identification of the cable, the capabilities of the device, and whether several charger ports are being used simultaneously. Heat, conversion losses, connector wear, and cable resistance further complicate the picture.

We’ll will look at how to test those claims rather than simply accepting the label. USB power meters can reveal negotiated voltages, current draw, accumulated energy, cable resistance, and supported fast-charging protocols. These measurements are useful when diagnosing a reluctant Raspberry Pi, evaluating a power bank, or determining why a device charges correctly with one cable but crawls with another.

Batteries, Projects, and a Giveaway

The battery discussion will cover lithium-ion charging stages, protection circuits, storage charge levels, heat, aging, and the difference between remaining charge and overall battery health. Wireless charging and portable power systems will also enter the conversation, including the losses and thermal compromises that tend to disappear from product packaging.

A FNIRSI FNB58 USB Tester with Bluetooth is up for grabs in this episode. The compact instrument measures voltage, current, power, energy, cable resistance, and several common fast-charging protocols. Watch the live broadcast for the entry details.

Viewers can submit questions during the show, whether they are choosing a charger for a bench project, investigating cable losses, repairing a USB-C lead, or trying to make a battery-powered design behave predictably. Mobile power may be portable, but the engineering compromises certainly are not.

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