Ember Mug 3 heats coffee for hours, but its $150 price and buggy app disappoint

Engadget has published a hands-on review of the Ember Mug 3, the latest version of the company's self-heating smart mug, which promises to keep beverages warm far longer than a regular cup. Priced at $150 and holding 14 ounces, the mug is noticeably heavier than expected because of the built-in heating element and small onboard computer.

The mug feels sturdy, is dishwasher-safe on the top rack, and features a thin LED under the logo that signals when it's powered on. It charges via an included coaster that doubles as a charging pad, meaning users need to be careful not to spill liquid on it.

Battery life and app troubles

During testing, the battery drained faster than expected — at 30% charge and the maximum 145°F setting, it died within two hours, and the coaster's slow charging couldn't keep up. The included lid claims to add three extra hours of heat retention, though this comes purely from better insulation rather than an additional battery.

The reviewer's biggest complaint was the companion Ember app, which frequently failed to reflect changes made to temperature settings, required repeated Bluetooth re-pairing, and occasionally threw error messages on launch. As an alternative, users can cycle through temperature presets using a single button on the mug's underside, though its placement is awkward when the mug is full.

Effect on taste

High heat also altered drink flavor: brewed coffee held at 140°F for an hour lost its fruity notes and turned more bitter, prompting the reviewer to settle on a lower 120°F setting. Espresso and milk-based drinks held up better, while herbal tea proved the best fit for prolonged heating. Compared to the original 2017 Ember Mug, which cost $80, the new price feels steep, leading the reviewer to suggest waiting for a discount, such as during Black Friday sales.