Any way to know USB battery usage?

[BayleeWylie]

[hondagx35]

Hi BayleeWylie,

this only works on the cubietruck (CT).
The CT is equipped with a dedicated input for a 3.7 Volt lithium polymer battery.
This battery will be charged while the cubietruck is powered from its 5V input.

Your 5V/1A 4500mAh battery pack delivers a constant 5V, so no way to measure the battery voltage.

Frank

[BayleeWylie]

Thanks for the reply!

So basically, what you tell me is that the Pi doesn't "detect" the battery because the voltage is as constant as if I used any PSU? Which means there's nothing I can do about that?

[PeteB]

Ohhh, there are ways...

Here is one example: "DROK Dual USB 2.0 Digital Multimeter Ampere Voltage Capacity Power Meter", $10 on amazon.

DROK is actually designed to make measurements while charging a battery, but you can use it to measure Voltage, Current, Power, and amp-hours consumed by your device.

In the pic below, C stands for "Capacity", the "0" in the upper right corner is the first digit, and the 782 on the second line shows the accumulated 782 milli amp hours since powered on. The "V" and the "A" are only meaningful in the Volts/Amps display.

So it shows my Pi has used 0.782 Amp-hr since I turned it on this morning.

It can be a pain sometimes, because the user interface is a single tiny button which cycles through the displays for voltage and current, power (watts), and energy (Amp-hr). However, it is remarkably accurate considering the $10 cost.

[BayleeWylie]

Thank you PeteB! It's definitely not an ideal solution, but at least it works