This is dependant on the model of the MySOS device that you carry.
610 Devices and some of our older 620 model units; we strongly advise you charge the device everyday, you may find charging the device overnight ensures your users will always have a fully charged device ready to activate.
Though our 620 device does not need to be charged as regularly and can receive a full charge in 4 hours and last 4/5 days with average usage. The device should be topped up with a full charge at least once every 3 months should the use of the device be irregular to prevent the battery from becoming damaged.
To visit our MySOS help pages, please click here - https://peoplesafe.zendesk.com/hc/en-gb/sections/360003981658-MySOS-Training-Content-