Archive for April 2nd, 2016
A recent ride got rained out after 27 minutes:
We didn’t get much more than damp and planned the ride with a bail-out route home, so it was all good.
The camera ran from STK Battery A, which had gone flat 37 minutes into a recent ride, so I popped it in the battery tester and drained the rest of its charge:
The dotted section says it had 0.85 W·h remaining after 27 minutes. Hand-positioning a copy of that curve against the full charge and discharge curve says the camera required 2.8 W·h. Eyeballometrically averaging the voltage over the leading part of the curve as 3.8 V says the battery delivered 0.74 A·h = 2.8 W·h / 3.8 V, then dividing that by 27/60 says the camera draws 1.6 A. That’s less than the 2 A guesstimate from previous data, but I don’t trust any of this for more than about one significant figure.
Running the camera for 27 minutes requires 2.8 W·h, meaning 37 minutes should require 3.8 W·h. The curve says that’s the capacity at the 2.8 V test cutoff, suggesting the camera also has a 2.8 V cutoff.
Looking at the discharge curves from yesterday’s post:
If all that hangs together, the C and D batteries should run the camera for just slightly longer than the A battery, but that doesn’t seem to be the actual result: they’re much better than that.
More rides are indicated …