Hitachi 18V Cordless Hammer Drill + 2 Batteries (Reconditioned Grade A) - $58.90 + Shipping at Bigskytool.com

More like 20% of the weight in most tools, but the percentage of total weight will vary with the tool.



Both cells can be made in essentially any voltage, but the common Nicad cell is 1.2 V and the common Li-ion cell is 3.6 V, so to get an 18 V battery pack requires 15 of the lighter Nicad cells or 5 of the Li-ion cells, resulting in a Nicad battery pack that is 20% heavier than the Li-ion battery pack.

The question, though, is whether you really want higher voltage. The higher voltage battery packs were introduced to deal with some of the limitations of Li-ion batteries. What we usually care about in tools is power density (how long will my tool run for a given size of battery pack) and torque (how much "push" does my tool have, how hard of work can it do). As a result, a 12V Nicad is comparable to an 18V Li-ion in terms of torque and power density. However, manufacturers keep making higher voltage battery packs because the buying public misunderstands this and thinks higher voltage is better.



We may have to "agree to disagree" on this one. From a practical standpoint, Nicad is better for most people - lasts longer, costs less, has more power density.



Depends on what you mean by "get 3-5 years". If you mean running with half-dead battery packs that won't hold a full charge, maybe. Also depends on usage. One of the biggest issues with Li-ion batteries is that they will take in the range of 100 charge cycles before degrading, while Nicads will take 250.



Nicads can be charged at a faster rate - the problem with charging any battery is heat. Li-ion batteries are extremely heat sensitive, Nicad less so. To charge a Li-ion at the same rate as a Nicad generates more heat in the Li-ion. That is why they don't make "flash chargers" for Li-ion batteries and the "15 minute" chargers take 30 minutes or more to charge a relatively low power density Li-ion battery on a hot day.

For casual usage, it just doesn't matter - none of the issues are big deals. For job site use, though, the charging delays for Li-ion alone make the case for Nicads.