A self-heating mug is a great idea, but for $150, Ember's third-generation flagship is a tough sell. While unboxing the Ember Mug 3, I pondered the hubristic battle humanity has long waged against nature. Ember makes mugs that keep drinks hot for hours longer than nature would otherwise ordain.

Coffee and tea are among the quiet luxuries that get me through each day, but I'm a torturously slow drinker who nursers a flat white for hours. The prospect of a mug that keeps drinks optimally heated was therefore catnip to a self-styled cappuccino connoisseur. The Mug 3 weighs more like a 24-ounce thermos at 14 ounces capacity, feeling sturdy with a metallic clink.

A thin LED under the logo informs when the cup is on, and it sits on an included coaster that doubles as a charging pad. However, the coaster-charger is not robust, and battery died within two hours when set to 145 degrees. With a full battery, the mug kept drinks consistently hot.

The coaster uses a USB-C connector rather than a hard-to-replace barrel plug for wall power. The Ember app is a mess. My biggest gripe with the Mug 3 is its app.

Often, I'd change the temperature or turn the Mug 3 off in the Ember app, only to later find it still locked to a prior setting. Additionally, I must re-pair the mug to my phone's Bluetooth about half the time I try to use it.