In that posture, with your feet flat on the floor, lift your right leg and place the ankle on the opposite knee. Reverse and repeat to stretch the muscle. Piriformis exercises also can be done lying flat on the floor, arms outstretched with palms facing the floor. Positioned about a foot from the wall, completely extend your legs and rest your heels against the wall. At that angle, rest one ankle against the opposite knee, just as in the sitting position.
Batteries, whether lead acid wet cells, AGMs or Gel should last at least five years. My Interstate deep cycle batteries are warrantied for seven. Now this supposes that you properly maintain them, and the number one reason for early battery failure is lack of, or improper maintenance. This is especially true of AGMs.
Lithium-ion batteries age. They only last two to three years, even if they are sitting on a shelf unused. So do not avoid using the battery with the thought that the battery pack will last five years. It won't. Also, if you are buying a new battery pack, you want to make sure it really is new. If it has been sitting on a shelf in the store for a year, it won't last very long.