If forgotten cold tea or coffee is the bane of your life, this smart temperature-controlled mug could be the answer

If forgotten cold tea or coffee is the bane of your life, this smart temperature-controlled mug could be the answer
The Ember 2 Mug looks like your average coffee mug, but it has coils underneath to keep drinks at the ideal temperature.Simon Hill/Business Insider

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  • The Ember Mug 2 is a smart mug that alerts you as soon as your beverage reaches the perfect drinking temperature and keeps it there, so it doesn't go cold.
  • It comes with a charging coaster and mobile app that allows you to choose your preferred temperature.
  • The Ember Mug 2 costs $99.95 for the 10-ounce model, and there's also a 14-ounce version and a travel mug for $129.95.
Table of Contents

When I get absorbed in work, I frequently forget about the cup of coffee on my desk until it's gone cold and lost its allure. My wife does the same thing with almost every cup of tea I make her. That hasty glug of forgotten tea or coffee is always unpleasant.

So what do you do? You can pour it away and make a new cup, or give it a blast in the microwave, but neither is an ideal solution.

The Ember Mug 2 is the top smart mug in our buying guide to coffee mugs because it aims to make your cold tea and coffee woes a thing of the past with temperature controls you can configure from your phone. A smart mug may sound ridiculous, and at $99.95, it's not a cheap purchase. I've gotten so used to it that after just one week of testing, I don't think I can go back to a regular mug.

It's not just about keeping your drink warm. There's always a gamble in that period after you make a cup of tea or coffee. How soon do you risk a sip? Too keen and you'll be rewarded with a scalded tongue, but leave it too long and you may miss the perfect temperature window when your hot drink is at its most pleasurable to slurp. The Ember Mug 2 removes all doubt by telling you when the ideal temperature has been reached.



The Ember Mug 2 is offered in black or white. It comes with its own charging coaster and a cable and power adapter for plugging it into an outlet.

  • Measures 4.2 inches high by 4.3 inches across (including the handle)
  • Capacity 10 fluid ounces (295 ml)
  • 90-minute battery life
  • Temperature range 120°F - 145°F (50°C - 62.5 °C)
  • Smart customizable LED
  • Waterproof up to 1-meter depth

It's ceramic and has a good handle. The only indication it's not a regular mug is the Ember logo and the LED light below it. Turn it upside down and you'll also see the metal charging rings on the bottom and the power button.

Set-up process

If forgotten cold tea or coffee is the bane of your life, this smart temperature-controlled mug could be the answer
Setting up the mug with the app took all of five minutes. Here's what you'll see when using the app and when getting notifications that your drink is ready.Simon Hill/Business Insider

After unboxing the Ember Mug 2, you'll want to plug the charging coaster in and set the mug on it to make sure the battery is fully charged. The power button for the mug is on its base.

The Ember Mug 2 connects to your phone via Bluetooth. You have to download the Ember app for Android or iOS, create an account, and then pair your mug. It was quick and easy, and I was able to pair the mug with my Google Pixel 4 and start using it within five minutes.


How it works

You configure your Ember Mug 2 using the mobile app and it's all very straightforward. The main screen says Empty until you put something in the mug, then it displays the temperature on a sliding scale along the bottom.

Tap the arrow at the bottom, and you can see several presets for different drinks. A latte is set to 131 degrees Fahrenheit, for example, while green tea is set to 137 degrees. Choose your beverage and stick with the preset temperature, or swipe left or right to increase or decrease it to suit your personal preferences.

There are some other options in the app. You can switch between Fahrenheit and Celsius, change the brightness of the LED, and set the LED color (I chose purple). The LED also changes color to signify different things, so red means low battery, solid white means your ideal temperature has been reached, and blue means it's updating the firmware.

Below the presets, you'll also find a Tea Timer section, which allows you to set an alarm for the perfect brew time. Once again, there are presets like three minutes for green tea or five minutes for black tea, and you can set your own timers for your preferred brew time.

You can pair up to six Ember mugs with the app.


If forgotten cold tea or coffee is the bane of your life, this smart temperature-controlled mug could be the answer
The white LED light means your drink is at the ideal temperature.Simon Hill/Business Insider

What makes the Ember Mug 2 stand out

To kick off testing, I poured a cup of coffee, picked coffee in the presets (which defaults to a temperature of 134 degrees Fahrenheit), and set my mug aside to work. A short while later, my phone pinged with a notification telling me that my coffee had reached the ideal temperature to drink. I had a sip and it was perfect. The mug then maintains that temperature until you're finished, or until it runs out of battery.

Ember said that the battery should last for 90 minutes and that seems about right. I've been using the Ember Mug 2 every day for a week now. I tend to drink my first mug of coffee quite quickly, but my second mug stretches out across the morning. When the battery gets low, the app pings to warn you, but that's only happened once.

I've been washing it out and putting it back on the charging coaster in my kitchen late morning, and then it's ready for tea service in the afternoon. It takes about two hours to charge up fully. It can then serve up a few cups of tea in late afternoon and evening before going back on the charging coaster overnight.

If you want the Ember Mug 2 to keep drinks heated for a long time, then you should put the charging coaster on your desk or wherever you usually sit. When you place it on the charger with a hot beverage inside, it will maintain that temperature indefinitely, though it won't recharge the battery any higher to avoid overheating.

There is also a two-hour inactivity shut-off, so if you don't pick it up for two hours it will switch itself off.


Cons to consider

It looks like a normal mug, but because the bottom section has to accommodate a battery and heating element, the capacity is limited. The 10-ounce Ember Mug 2 I've been testing is a little small for my tastes. There is a 14-ounce model, but it's an extra $30 and it's sold out at the time of writing.

The mobile app doesn't always connect immediately, but so far, it's always been easy for me to tap the picture of the mug in the app and reconnect. I say "so far" because some user reviews have complained about connectivity issues.

The only other problem I've had is that sometimes it sends more than one notification about your drink being at the ideal temperature. This has only happened a couple of times in a week of testing, but it was a minor annoyance.

You can only hand wash the Ember Mug 2 as the charging coils are not dishwasher safe.

The bottom line

The Ember Mug 2 is the best smart mug around. It's surprisingly awesome having your coffee at that perfect drinking temperature for the entire cup. After a week of using the Ember Mug 2, I don't think I can go back to a normal mug.


If you like your coffee, tea, and other hot beverages to be at the perfect drinking temperature, then you're going to fall in love with Ember Mug 2.

Which model should you get?

You can buy the Ember Mug 2 in black or white with a 10-ounce capacity for $99.95, and that's probably the best model for most people. The larger 14-ounce model, which only comes in black, costs $129.95. There's also a travel mug with a leak-proof lid that holds up to 12 ounces, but it costs a hefty $179.95.

What are your alternatives?

There are other smart mugs out there, such as the Cauldryn Coffee Smart Mug at $82.95, but none as good as the Ember Mug 2. If you're on a budget, you could also consider an insulated mug, or a warming plate for regular mugs, like the Bestinnkits Smart Coffee Warmer at $27.99.

Pros: Keeps drinks consistently warm, LED and smartphone notification alert you to the ideal temperature, has handy charging coaster, additional brew timer for tea

Cons: Expensive, limited mug capacity, limited battery life, not dishwasher safe

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