Cordless drill battery options
Generally speaking, NiCad batteries are older technology and offer very little that can’t be topped by the technology found in the new lithium-ion batteries.
For one thing, Li-ion batteries are very light, about half the weight and size of their NiCad cousins. This allows manufacturers to put big power into small packages, keeping the higher voltage tools a useable size and weight. Secondly, Li-ion batteries self discharge at a very low rate. While NiCad batteries will go dead by themselves in a relatively short time, the lithium batteries will hold their charge for up to several months.
Finally, most lithium batteries deliver a very linear power. What this means is that unlike NiCad-powered tools that gradually lose power as the battery weakens, Li-ion tools will run at a constant voltage until the tool senses the voltage drop and cut the power. This prevents damage which can be caused by over-draining batteries.
Don’t get me wrong, NiCad tools have been around forever, and can represent a good value, but as tool technology advances, I am seeing fewer and fewer NiCad options available, as most brands switch to the new technologies.