Wow! I learned a lot. Thanks. I had previously read that the faster the charge, the faster the batteries wear out,
and found this as a good explanation (there's a lot of good stuff there too):
Figure 2: Cycle performance of Li-ion with 1C, 2C and 3C [rates of] charge and discharge.
Charging and discharging Li-ion above 1C [rate] reduces service life. Use a slower charge and discharge if possible. This rule applies to most batteries....