Spring uses a CR2450 coin cell battery that lasts up to 6 months and it’s easily replaceable. The CR2450 coin cell battery is easily available and can be purchased from most local convenience or hardware stores.
In order to replace the CR2450 battery in Spring, unscrew the battery lid from the bottom of your Spring. This can be done with a coin or a coin-like item and the battery lid should just pop out so the new fresh battery can be put in.
After you placed the fresh battery make sure to sync your Spring.