TomTom on Twitter: "@MFergusonAuthor Hi, Watch batteries not holding charge can sometimes be caused by the operating software misreading the charge in the battery. Please apply the Factory Reset described in this
TomTom Spark 3 Cardio Battery Replacement
China Replacement GPS Smartwatch Battery for Tomtom Spark 3 Battery 3.7V 280mAh - China for Tomtom Spark 3 Battery, Rechargeable Battery