Curious as to just how long a battery should last before it is expected to reach its end of life span (years)? My bike its almost 3 years old now and the battery seams good as new. Just anticipating how old they get before everyone is facing buying a replacement?

My front wheel has developed an annoying squeak that I can't make go away. I've narrowed it down to the front axle bearings (or so it seems). Have chatted online with Rad several times in past few days to trouble shoot, but they aren't any help. Can't advise me how to service the bearings. Pretty sure they need lubrication.
Has anyone experienced this issue? Does anyone have instructions for me on how to disassemble and lube?