You can check the battery level of your Withings Body Cardio by going to My devices > Body Cardio from the Withings Health Mate® app. If the battery level reaches 5% or less, we advise that you charge the battery. To do so, connect your Withings Body Cardio to a power source using the USB cable provided with the scale.
Charging the battery can take up to five hours. You can press the button on the side
of the scale while it’s charging to check the battery level.
Note that you shouldn’t use your Withings Body Cardio while it is charging.