-snip-
I lied- 15minutes to 85%- 30 minutes to full on the Bosch. Can't find a time offhand on the Milwaukee- but I've never drained a battery before the next one was ready.
Never felt a hot battery, but I pay little attention to them until I'm ready to use them.
I doubt slower charging would make the batteries last longer or manufacturers would sell a slow charge charger & tout its benefits. And I probably wouldn't buy one. It is a tool- not a collectible that I want to hang on to forever. If I get 2 yrs [the warranty period] out of the tool I'm happy, it has made my life $100 easier-- and there will be a new & better technology out there.
Jim