3 ms·You dont leave it flat, like every other battery device.by worthless-trash 2y agoYou dont leave it flat, like every other battery device.phatfish 2y agoYou are far more organized than me if you remember to keep every device with a battery fully charged.addaon 2y agoJust swap batteries on critical devices (and rotate them to less critical, eg flashlight -> tv remote) once a year when you check your smoke alarms.