Kill-A-Watt measurements

[manawyrm]

When the screen is turned on, power consumption is quite constant with a variance of +/- 0.5W. It's puzzling that occasionally no power is consumed for a few seconds when the screen is turned off. Maybe the battery is taking over during these short intervals?

Yeah, what happens here is, that the battery is charged, the battery voltage cutoff (~4.35V) is reached, the charger switches off, the battery gets discharged until it's under the hysteresis switching point and then the charger will draw current again. 

If you want to do real reliable power measurements I recommend opening up your PBP, unplugging the battery (very important!), and then plugging the small loose jumper cable together, which will allow you to power the Pinebook Pro from the wall supply alone. 

You can then measure the power consumption pretty reliably. 

I have used a clip on ampere meter around both wires (don't get fooled by the wire colors, both red and black are connected in paralell) to measure the current draw directly. With the kill-a-watt and power supply you'll probably add another 10-15%, but that's okay.  

About the power draw in the longer test: Have you ensured that the PBP is properly ventilated? The underside can get pretty hot and the RK3399 would limit it's maximum TDP (and thus power draw) to prevent overheating.

Here's a photo of my measurement setup: 
 
You can see that the PBP is drawing ~ 1.18A @ 5V, running Manjaro with full screen brightness at idle CPU.