Re: prolonging tool battery life
Once charged, batteries don't like to sit. It is better to use them on a regular basis, the charge/discharge cycles keep the internal plates clear of crystallization, which is what degrades them over time.
If you're only using them once a month, then I'd suggest investing in a good corded drill such as a Milwaukee or other good name brand. Yes, you have to deal with cords, but you won't be hampered by underpowered or dead batteries, and in the long run, you'll save money by not having to prematurely replace batteries.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!