Ember Mug Battery Replacement
What’s an Ember Mug?
An Ember Mug is temperature-controlled mug that keeps beverages (coffee, tea, etc.) at a set temperature. Sounds completely unnecessary, right? It is, until you try one and realize how nice it is to drink your coffee at exactly the temperature you want. No more lukewarm or cold final sips, and no rush to drink it while it is hot and risk burning your mouth.
It is definitely a first-world luxury; however, like many first-world luxuries, once you try it, it is tough to go back to the way things were before. It is also fairly expensive (~$150 for a coffee mug!) but makes a nice gift, especially for someone who enjoys coffee or tea but would never buy it for themselves.
I got one as a work giveaway. So I got to experience it (and get hooked) for free! If you want one for yourself or someone else, you can order one from Amazon.
So Why Are We Talking About It?
Turns out the batteries on the Ember Mug are prone to deteriorating. It is possible that mine sat in storage for a while before I got it, contributing to shorter battery life. Regardless, I used it for a cup of coffee a day, 4-5 days per week, for roughly 9 months before it began losing its charge rapidly. The mug and its companion app would report a full charge but the battery would discharge completely in ~10-15 minutes. Previously, it lasted over an hour, maybe as long as 90 minutes.
Factory resetting the mug did not solve the issue. I contacted Ember support, who asked me to answer a number of questions and provide a picture of the serial number. A month later, they asked me to provide a video. Two months after that they replied and asked me to provide a video again. By that point I was done with their support process and had received a different mug as a gift. Based on what I have read online, their customer support is hit or miss.
I should also add that the Ember Android app is terrible. The first time the mug is connected via Bluetooth, it works great. Be sure to set your desired temperature on this initial connection because on any subsequent attempts to use the app, it will fail to connect to the mug. The mug still works and remembers the temperature setpoint without the app, but if you want to adjust anything you have to go through the entire Bluetooth pairing process again.
The new mug I received–a NextMug–did not have an app, which was a bit of a relief after the Ember Android app experience, but it only had 3 preset temperature settings. I used it for over a year with no issues, and I would recommend it to someone who would like a heated mug without the complexity of an app.
But What If We Could Revive It?
The Ember mug was relegated to storage, but every once in a while I would come across it and wonder if it might be possible to replace the battery. It seemed like such as shame for it to become expensive e-waste. Ember offers no battery replacement, but surely the hive mind of the Internet could make it possible, right?
I found various information on Reddit, YouTube, and on forums. Part of the challenge of finding the right information is that Ember makes several different kinds of mugs and dissambling them varies from model to model. I eventually found this thread on iFixit, which has instructions for the Ember mug. The thread is a bit hard to follow, and also includes reports from people who tried things like drilling into the base to separate it from the mug.
The rest of this post details what worked for me (no drilling required!), along with pictures.
Disclaimer
The information in this post is for educational purposes only. The Ember mug battery is not designed nor intended to be user-replaceable. Attempting to follow these instructions may result in harm to yourself and/or the mug. I am not responsible for personal injury, fried circuits, or voided warranties. Proceed with caution at your own risk, and please be careful handling the batteries.
Also, Amazon links in this post are affiliate links. If this post helps you out, use those links and buy me a coffee!
Replacement Battery
You will need a replacement battery. I ordered this one from Amazon.
Removing the Base
By far the hardest part of the process is removing the base, which must be rotated slightly to separate it from the rest of the mug and access the battery. The base is smooth and curved, making it difficult to grip and rotate. Some people report using a strap wrench, but I was successful using rubber gloves.
The key is to turn the mug on so that the light turns on. This will allow you to see whether the base has rotated. Initially, the light will be centered under the ember logo:
Ember mug with light illuminated
Hold the mug in place and grasp the base as best you can. It might be easier to place the mug upside down on a table in order to apply some downward force to help grip the base. Rotate the base a few degrees clockwise. It will be difficult to tell whether the base has rotated if the light is not illuminated. There is a tab on the underside of the base that will prevent the base from rotating any further.
Mug illuminated with base rotated
The next challenge is separating the base from the rest of the mug. Again, it is difficult to grip the base. I gently wedged a woodworking chisel in the groove between the base and mug and carefully twisted to start separating the two pieces. I worked my way around the base until it created enough of a gap to use my hands.
Mug and base separating
Carefully slide the base completely free of the mug. There is a ribbon cable connecting the base to the mug.
Closeup of ribbon cable
There should be enough slack to allow the base to lay flat with the mug next to it with the ribbon cable still attached.
Base with ribbon cable still attached
Removing the Battery
Remove the three (3) screws securing the metal housing.
Ribbon cable side of metal housing
Other side of metal housing with two screws
Remove metal housing to expose the battery. It is a tight fit and may need to be wiggled loose.
Base with metal housing removed
Carefully disconnect the ribbon cable.
Disconnected ribbon cable
Remove the remaining screw securing the circuit board from the ribbon cable connector side. On the side opposite the ribbon cable connection is a housing for the light. Pop this free and remove it from the base.
Light housing removed from base
Remove the battery and circuit board from the base. The battery should be glued to the circuit board so that they are a single unit.
Battery removed from base
Flip the battery and circuit board over. Carefully disconnect the battery cable from the circuit board.
Circuit board with battery connected
Circuit board with battery cable disconnected
Once the battery cable is disconnected, carefully separate the battery from the circuit board. It should be glued together. Exert steady pressure until they begin separating. Discard the old battery.
Closeup of original battery
Replacing the Battery
Connect the cable of the new battery to the circuit board and place them back into the base. It will be a tight fit.
Base with new battery
Replace the single screw on the ribbon cable side and connect the ribbon cable.
Single screw and reconnected ribbon cable
Replace the metal housing and three screws securing the housing.
Metal housing with screws
Carefully slide the base back into the mug. It will fit very tightly. Assuming the battery has some charge, it will be helpful to turn the mug on to use the light to help align the base. Turn the base counterclockwise until the light is centered under the ember logo. If the base will not turn, remove it and check to ensure the tabs on the mug and base are properly aligned.
Base reattached to mug with light illuminated
Ember mug with light correctly aligned
Success (hopefully)!
If everything went according to plan, you now have an almost-brand-new Ember mug. I replaced my battery about in June 2025 and it has worked flawlessly since.