A PAIR of genuine RENATA CR2325 batteries (recommended by L&B) for devices such as;
For devices such as the VISO; After battery replacement, reset the device, the battery system requires 2 minutes to calibrate itself before displaying the correct status. While calibrating, the battery icon toggles between full and low.
These are the batteries sold by L&B themselves - this helps to eliminate the issue with the cheaper 'knock-off' variants available online which have lower voltage outputs - hence your device still reads the new batteries as almost empty!
To reset the device; Using a paperclip, insert it into the small hole at the rear of the device. Press and release to initiate a reset.