The Ember Mug is a fancy (and expensive) cup that works to keep coffee at exactly the right hot drinking temperature for hours at a time.
But how does the Ember Mug work to keep coffee hot? What is the technology behind this cup, where does it work well, and what are it's limitations?
The Ember Mug uses electricity from it's dual lithium-ion batteries to heat up a heating element in the bottom of the mug which keeps your drink hot. Multiple sensors are used to turn the mug on when liquid is poured in and to keep it at a consistent temperature.
It's a pretty clever idea and actually one that is pretty hard to pull off. A look at the different Ember Mug alternatives shows that not many companies have been able to make something similar and a few have tried and failed.
In this article we'll dive deep into how the Ember Mug works and how it can keep tea, coffee or any other drink at that perfect temperature.
A Heating Element On The Bottom Keeps Your Drink Hot
The Ember Mug is made of stainless steel with an interior ceramic coating so no flavors leak into your drink.
The reason stainless steel is used is because it is durable but also because the stainless steel can conduct heat from a heating element in the bottom of the Ember Mug which then heats up your coffee.
There is no stirrer or any way to move liquid through the Ember Mug. Instead it relies on convection currents to create an even temperature for your coffee.
As the heating element warms up the liquid towards the bottom of your coffee that hot coffee naturally rises (heat rises, cold sinks) and is replaced by colder coffee which is then heated up and so on.
So no stirrer is needed, your drink naturally disperses heat pretty evenly giving you an even cup of coffee.
Ember Mugs are Good a Keeping Drinks Hot, Not Making Them Hot
One of the hard things with a battery powered heated coffee mug is that heating elements tend to use a lot of power. This drains batteries really quickly and can even overheat and burn out chords.
This is why so many 12 volt heated coffee mugs have a tendency to break so quickly. They often burn out.
The Ember has dual batteries but these don't have a huge capacity. The way Ember manages power and gives you 1.5 hours of battery life in the smaller unit and 3 hours of battery life in the larger unit is by having a heating element that doesn't use much power.
This means however it isn't super powerful and can't heat up drinks, it can only keep drinks hot. The Ember Mug can keep drinks hot between 120-145ºF (48-63ºC).
Trying to heat up drinks will drain the battery super quickly and on my Ember heating FAQ page we talk about how the Ember won't even work if liquid is under 100ºF (38ºC). If you want a battery powered coffee mug that can actually heat up drinks and bring it to boil then check out my Cauldryn vs Ember comparison.
Ember Uses Sensors To Turn On/Off Automatically and Keep Your Drink at the Perfect Temperature
The Ember Mug is full of a variety of sensors that help it to work so seamlessly.
It senses liquid
The Ember Mug has a sensor that detects when your mug has liquid in it.
When it sense liquid it will automatically turn itself on. When it senses that you've drunk all your liquid it will automatically turn itself off.
The Ember Travel Mug on the other hand has an on/off switch that you'll need to use to turn it on.
It sense temperature
There are sensors inside the Ember Mug to detect the current temperature of your drink.
It will display this temperature in the Ember App with a little wavy line that will go up or down as your temperature goes up or down.
It senses movement
The Ember Mug also senses movement. When plugged into the wall via it's charging coaster it'll run for 2 hours before turning itself off.
That is unless you pick it up and move it around. When you pick up your Ember Mug it detects this and will continue to keep your drink hot for another 2 hours.
When Plugged In Via It's Charging Coaster The Ember Runs All Day
The Ember has a limited battery life of 1.5 hours hours for the smaller mug and 3 hours for the larger travel mug. This is an improvement on the original Ember Mug which only lasted 1 and 2 hours respectively. Read my full Ember Mug 1 vs Ember Mug 2 comparison to make sure you're getting the right one.
However, the Ember Mug comes with a cool charging coaster. You can simply put your mug onto this coaster and it will use mains power in order to keep your coffee or other drink hot indefinitely.
As mentioned above it runs for 2 hours without being used before it switches itself off so you aren't heating a drink you've completely forgotten about and waste power.
However, if you pick up your Ember Cup for a drink it'll detect this and the 2 hour clock will be reset.
Ember Doesn't Feature Phase Change Material
I saw some articles on the Ember Mug that claim it uses phase change material in order to quickly cool down coffee and keep it at the perfect temperature.
Phase change material (PCM) is a material that absorbs energy as it goes from a solid to a liquid as it gets hotter. Then as it cools down and resets into a solid again it actually lets off a lot of heat. The right PCM that turns to a solid around 140ºF (60ºC) can be used to keep coffee at a perfect temperature for longer.
However, the below video by JerryRigEverything shows that when he cuts open the mug it just has a super thin layer of insulation
So the Ember Mug does NOT contain any phase change material to quickly cool down your coffee or to help keep it at that perfect temperature. The only cup I am aware of that uses phase change material is The Burnout Mug.