H.L.H: I usually check mine once a week, partly because some are for security and wildlife at the same time. This last time was ten days. I carry a multimeter, spare batteries and extra SD cards. I swap out the cards and if my batteries have a lower reading,1.25 volt or so I swap them out. I have 45 to 60 miles one way to travel depending on location. I would be disappointed to have battery or camera failure and missed out due to not checking a little sooner. I got into a faulty shipment of rechargeable batteries, and all one needs is one battery to fail out of 4 or 6 and your camera shuts down. All batteries tested 1.55 volt out of the package, but the faulty ones failed to charge back up to spec.Thanks for posting the question.