Hi, I am starting my 3rd summer with the 56V 5.0A push mower. The past two seasons have been great. No problems. I sharpen the blades almost every time I mow, and I try to keep the battery in the cool house (instead of the hot garage). However, this season I'm noticing my battery is only lasting half as long as last season before it needs recharging. I used to be able to mow my 0.4 acre yard without need to recharge, but this season, I keep having to recharge the battery mid-mow. I'm concerned that the battery is already 'wearing out.' What should I do? Is this normal? I would hope that I wouldn't need to get a new battery already.