I must say you have been very lucky. For many years at work I used an excellent Logitech trackball mouse, then as I was nearing retirement and I bought a Mesh computer it was supplied with a Logitech wireless trackball and keyboard, both of which required batteries. After some time I got some re-chargeable batteries, but had to keep switching both of them off because on a good day I could get as much as 3 hours from a set of batteries. Complaining to both Mesh and Logitech didn't even produce an acknowledgement let alone any help. I then bought - against my better judgement, I must say - a Microsoft keyboard and an Optical trackball mouse, and after more than 4 years have only had to replace keyboard because I spilt Coca cola on keyboard. I, personally, would not trust Logitech again!