I have a set of Dewalt cordless tools with both 18V NiCad and 20V LiIon batteries (I also have an adapter that lets me use the 20V batteries in the 18V tools). The tools are only a few years old, and the drill and impact driver both have LED lights to illuminate your work area. The LED lights when depressing the trigger slightly.
I used both the drill and impact driver one day and then left them overnight. Both tools are 18V; I used an 18V NiCad in one and the 20V LiIon (with adapter) in the other. I went to use them again the next day, but both batteries were dead. The direction / safety switch on both was set to "off" and the tools were not used, so I was surprised to find the batteries depleted. Aside from the inconvenience, is this bad for the battery or the tool? Does this indicate a problem with either?
The tools and batteries are normally stored / charged in my garage, so they've been exposed to some colder temperatures (nighttime lows of 40F typically, though some nights as low as 25F) recently, which can affect battery charging. Days have typically been relatively warm (at least 60F).