Kill-A-Watt measurements
#4
Cool setup. I have not used my ampere meter for these measurements. Right here I'm not concerned about precision and I prefer the convenience of a kill-a-watt. I can easily use it the same time I use the laptop.

(02-28-2020, 08:20 AM)manawyrm Wrote: 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. 

Why does the charger switch off? It's supposed to a) charge the battery as long as it's not fully charged while b) powering the laptop circuitry all the time.

(02-28-2020, 08:20 AM)manawyrm Wrote: 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.

I see this behavior even with 1 cm of free space under the laptop. TDP does not explain the observed behavior, does it?


I see a lot of weird behavior once the system is running for a couple of hours ... preferably after the system got stressed for some time in the past.



Half off topic. I was grep'ing my way through the kernel source and learned on how to cap the max temperature to, say 55C.

Code:
manjaro: # echo 55000 > /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_temp

The kernel is then throttling the cpu frequencies to reach that temperature. The default trip point comes from the device tree. Rockchip set it to 70C and someone from Pine64 re-set it to whopping 80C.

Here are current frequencies under load when temperature is caped to 55C

Code:
manjaro: # cat /sys/devices/system/cpu/cpu?/cpufreq/cpuinfo_cur_freq
1416000
1416000
1416000
1416000
1800000
1800000


Messages In This Thread
RE: Kill-A-Watt measurements - by ab1jx - 02-23-2020, 04:42 PM
RE: Kill-A-Watt measurements - by manawyrm - 02-28-2020, 08:20 AM
RE: Kill-A-Watt measurements - by Der Geist der Maschine - 02-29-2020, 11:00 AM

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