There was a time when everyone told me that the way to get the longest service life out of (solid state) rechargeable batteries was to let them run all the way down frequently. Recharging them when they were only half down supposedly "trained" them not to use the rest of their charge. I don't know if this was ever true, but is it true now? I used to put the charger on my Kindle every night, and the battery wore out in three years. Would I be better off to let the new one run all the way down before recharging it?