When I moved house about five years ago, I stupidly left my motor mower in the shed!! Stupid Me! So, over the last five years, I've been getting a 'Jim's Gardening' guy in to mow and clean up the garden every three or four months, at $75-$100 a go!
A while ago, I learned that one of my sisters had brought a Ryobi Battery Mower, so this week, I've borrowed it and mowed my lawns. It did a good enough job for me. The Battery takes about two hours to recharge.
Back in a previous life, I was an Electronic Technician, and, at the time of Ni-Cad batteries being introduced, the recharge story was that Ni-Cads should be fully discharged occasionally, otherwise they developed a 'memory' such that if they were regularly used/discharged to a particular amount, whenever they got to that level, they would stop working.
They then had to be 'manually' flattened by continually being turned on .... and turned on .... and turned on ... Until they were 'flat', so that they could then take a full charge and be 'right-as-rain'!!
With that in mind, and remembering that it supposedly only takes two hours to fully recharge the Mower Battery, would it be better, after use, to leave the battery 'Flat' or 'flatish' or should the battery be fully recharged ready for use .... even though that use might be a month or two hence??