Is the DeWalt also 18 volt? Is it just a more powerful 18 volts? What's up with that? :^)

(Seriously, I would've naively assumed that the only thing that affected the powerfulness of the drill was how much power it used...)

Power is the result of battery voltage + tool efficiency (motor, switch, transmission etc.).

Runtime is the result of battery voltage + battery amp-hour + tool efficiency (motor, switch, transmission etc.).

Chemistry determines the size and weight of the battery and it’s durability. Chemistry does NOT impact power or runtime.

The last statement is not entirely true. Li-Ion batteries can overheat if drained at very high rates. There is current-limiting circuitry in either tools or batteries that prevent that from happening. I compared Makita BHP451 with DeWalt DC925 with NiCd battery, and even though Makita claims to have higher torque and lower RPM (300 vs 450 on DeWalt), drill got stuck when I tried to drill a pine 4x4 with a 2 inch hole saw, while DeWalt just slowed down. DeWalt's Nano batteries have higher discharge current (=more power) and lower capacity as a tradeoff. Cells in Makita batteries are 1460 mAh while DeWalt 18v nano's are 1100 mAh, yielding ~3 and 2.2 Ah (2.3 Ah for 28v and 36v) batteries respectively. Current-limiting circuitry is a good thing.

The above information was created by the author of the awesome forum at Digital Reality Crew.

http://forum.drc.su/dewalt-nano-battery-technology-faq-vt4382.html

What is the technology inside the DEWALT batteries with NANO Technology?

To create the battery technology initially introduced in the 36V system, DEWALT partnered with A123Systems, a developer of a new generation of lithium ion batteries that incorporates nanoscale technology developed at and exclusively licensed from Massachusetts Institute of Technology. The DEWALT battery technology has a unique NANO-phosphate lithium ion design that offers a high level of power, runtime and life compared to conventional lithium ion technology. For example, the NANO-phosphate battery delivers 2,000 recharges (over 3x more life than any other formula of lithium ion we evaluated). NANO-Phosphate is available in three voltages:

* The 36V battery delivers 2x power and 2-3x more run-time compared to 18V; however it weighs the same as a 18V NiCd battery.
* The 28V battery delivers increased power and up to 50% more run-time compared to 18V; however it weighs the same as a 14.4V NiCd battery.
* The 18V nano-phosphate batteries are smaller in size and 1 lbs lighter in weight than their NiCd or NiMH counterparts. They are also backwards compatible with the existing DEWALT line of 40+ tools.