Its the same one ASUI uses and I've seen it a lot. The transition to orange at 2.0 is a bit low because I rarely see yellow. Although the orange and yellow are hard to distinguish from each other, I'll either change the 2.0 to halfway between 0.8 and 14.0 or remove orange.
ASUI only tracks last hour and last X hours and it passes the last hour rate to the applet. Last minute tracking is not possible unless you are bleeding 0.1% or more per minute. The applet rate only updates when battery capacity changes. I can probably add a 60 second timer in the applet that resets when it receives a drain update otherwise it will request a 'decaying' update from ASUI. That way the applet's rate will decrease with time when no BME updates are being sent, just like ASUI does when the battery widget is visible.