Don't let your battery fully discharge. If you let your battery die frequently, you are putting extra strain on the battery. Most companies recommend discharging the battery once in cobalt mine every charges or so.
Why is this important? If you have a relatively new PC the only problem you will get are error messages relating to the clock on start up. No Lithium mines Ontario big deal. If your PC is older then a low battery could be a nightmare. I had a PC which once every few months refused to boot. Rather than take the PC in for repair or start replacing parts myself the first thing I did was look at the BIOS settings. It was soon obvious that the BIOS settings were corrupt (wrong bus speed). I put a volt meter on the battery and sure enough it was reading 2.2 volts.
These large battery packs take up a lot of room and are pretty heavy, which adversely affects the fuel economy and the storage space in most hybrid cars. These batteries get their power from regenerative braking and/or from the gas engine. Also, they are very expensive, costing thousands of dollars to replace. Which is why they are guaranteed for the life of the car (read you warranty, some states make automakers guarantee the battery for 100,000 miles).
I don't consider the Craftsman Multi-tool as a heavy-duty tool. In fact the tool will get hot around the Lithium battery stocks area if you use it on too large a task (3 to 4 batteries in a row.) It is just a great tool for those special small to medium jobs around the house that I have all the time. It is a great "around the house" tool. If you need a tool like this to work for you all day long or have a large project like scraping an entire house before painting you really should buy a heavier tool like the Fein Multi-Master.
When you do something processor intensive, plug in the charger. Not only because this usually triggers a higher performance setting and give you more horse power to play with, but because when the battery is discharged at maximum rate it's more probable to overheat, and heat is a great enemy of Lithium-Ion.
So, it's easy to see how a lithium 18650 battery, and Li-ion cells in general, have found there way into the homes (and hands) of many modern consumers.