Dave.

Lithium ion batteries have a sweet spot of around 60 to 80 percent charge where very little wear takes place to charge or discharge. If you could keep it to just that 20-30 percent usage in that range it would pretty much last ten thousand cycles.

Charging to 100 or discharging below 50-60 percent accelerates the wear on the battery, but it is still much better than the wear rate on lead acid batteries that are cycled in a similar manner.