Expert ~ Optimizing Power Consumption

Optimising power consumption

(kindly contributed by @gba-gbob)

In the world of micro FPV sensible power consumption is important. Below measurements should give you a rough idea on what savings can be made.

Setup / Test environment

• Setup: Raspberry Cam v2, M08-50 RT5370N Wifi adapter
• Lipo battery wired directly into header pins 2->3.8 VDC, 6->GND
• Very likely transmitter power adjustment had no effect on this particular setup
• Setting over_voltage less than -4 causes reboots
• Reducing cpu arm_freq below 600 has very minimal effect power consumption < 10ma
• Measured with Vici VC99 multimeter

consumption mA@voltage	change mA	config change	notes
400-430@5v	0	none
[email protected]	0	none	keeps rebooting not usable
400-430@5v	0	force_turbo=0
360-370@5v	-50ma	arm_freq=600	10% cpu idle VIDEO_BITRATE=auto, 48% cpu idle VIDEO_BITRATE=3000
300-320@5v	-50ma	VIDEO_BITRATE=3000
290-310@5v	-10ma	FPS=30
310-350@5v	+30ma	DATARATE=2
300-330@5v	+15ma	DATARATE=3
290-310@5v	0	DATARATE=4
260-290@5v	-25ma	/usr/bin/tvservice -o	switching of hdmi output
260-290@5v	0	over_voltage	values -4 to 6 no effect
260-290@5v	0	over_voltage_sdram	values -4 to 6 no effect
260-290@5v	0	txpower_ralink	values -5 to 5 no effect

After optimization

• 260-290@5v (100-110mA Wifi adapter)
• 360-390@3,8v (130-150mA Wifi adapter)

TODO

• Find wifi card obeying transmission power settings hopefully allowing sub 200ma@5v setup.