Ed Huntress wrote:
On Wed, 29 Jul 2015 23:24:58 +0000 (UTC), John Doe
wrote:

Took it out in sunny afternoon 98°F weather for a 6 mile trip. The 20V
5AH battery shows one out of three bars remaining. Drill got hot but
there was no performance change.

This is really interesting, but I'm having trouble with some of the
numbers. Say the "two bars" consumption equals, roughly, 3 A-hr. At 20
volts, we have 60 W-hr. Just guessing here, but say you travelled that
6 miles at 12 mph.

That means the drill was drawing an average of 120 W for a half-hour.
Let's be generous and say that the system efficiency is 80% from
storage to power at the drill shaft. So, given chain and friction
losses at the tire, you have 1/8 hp driving the bike.

Will that be enough to move you at 12 mph? I'm not familiar with the
actual power consumed by these bikes, but that sounds low. Am I
missing something?


Well consider also that the bars may not be an accurate indicator of the
state of charge.