Depending on your use and the configuration of your infrastructure, you will have to change the batteries every 2 years or even less often.  We chose to use non-rechargeable batteries for the following reasons :  For an equilvalent size, rechargeable batteries would only provide approximately half the autonomy of our current solution (currently 2 years and more) The extremely low power consumption of our devices would result in a very important Self Discharge phenomenon on rechargeable batteries, which would once more affect autonomy The replacement of a battery is a rare and quick task. Maintenance is made easy, compared to having to recharge batteries every couple of months Grab the plastic tool provided with your ROOMZ Display, and align it with the  groove located in the back of the device (under the 3rd button, when facing the device): Pull on the tool, the display's cover will come loose: Using a paperclip, unfold the strips sticking on the battery, that will help you slide the battery out: Once out, just replace the battery with the new one, by disconnecting and reconnecting the plug: Hold the wire coming out of the Display (shown by the arrow), as it might slide back in the device once the battery is disconnected Finally, gently slide the new battery back in the device You can re-use the strips and fold them back in place to make the next change easier. Take care of the wiring before closing the lid