Test with interface board, 12V PS and HX711

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Emil's picture
Test with interface board, 12V PS and HX711

I have testet the first HAT board, with a 12 to 5V adapter and the HX711 onboard
Have done several test with different connections
I'm using a Raspberry Pi 2 model B

Pi + HAT , LAN, Scale
Idle: 0,10 A
running hive.sh: 0,13 A

Pi + HAT , LAN, Scale, 1 x DHT22
Idle: 0,13 A
running hive.sh: 0,14 A

Pi + HAT , LAN, Scale, 2 x DHT22
Idle: 0,13 A
running hive.sh: 0,15 A

Pi + HAT , LAN, Scale, 2 x DHT22, 1 x TSL2591
Idle: 0,13 A
running hive.sh: 0,16 A

Pi + HAT , LAN, Scale, 2 x DHT22, 1 x TSL2591, Huawei E180 3G USB modem
Idle: 0,16 A
Connected to internet: 0,20 A
When running traffic on the adapter is sometimes comes up in 0,30 A

Pi + HAT , WLAN adapter, Scale, 2 x DHT22, 1 x TSL2591, Huawei E180 3G USB modem
Idle: 0,19 A
Connected to internet and WLAN: 0,27 A

The power consumption on 3G/4G and WLAN will vary a lot on the different signal strenght from the senders

I see a problem on the internet connection that the NTP protocol sends a lot of packages to keep the time correct. I have tried to change the poll time for this but with no good success, maybe the NTP protocol needs to check when the connection is up, and then stop until next time to save a lot of power

Emil's picture
Power down USB and ETH

Here are the test when USB and ETH is powered down

0.16A Eth + 3G modem + HDMI on
0.16A Eth + 3G modem + HDMI Off
0.14A 3G modem + HDMI Off
0.10A USB power off + ethernet cable in + HDMI Off
0.08A USB power off + ethernet cable out + HDMI Off

So for Solar powered stand alone hive power would og down from 0.14A to 0.08A (a bit more when hive.sh runs)
This test is done with load cell, 2 Temp sensors and 1 LUX sensor installed

I also attach the /etc/init.d/usbpower.sh file which can be run from crontab

Nate's picture
How do test?

Emil, how do you test power consumption? is it an internal counter, or do you use an external meter?

Emil's picture
Power check

I use a HAT board with 12V input. I connect my external meter between the external 12V adapter and the + input on the HAT board

Paul's picture
USB power meter

There are some cheap USB power meters. They give you current at 5 volts and must be converted to watts to be compared with 12 volt current readings. Adrian uses one. I took a USB extension cable, cut in half. and wired a multimeter in series.

Esa's picture
got similar values varying

got similar values varying between 0.13A to 0.17A, mostly around 0.15A (measured with multimeter in between powerlines)

I had 2x USB Temperhums, load cells, USB-WLAN adapter connected.

Was there any plans, ideas discussed here in forums about lowering the power usage by cron settings, powering off equipments etc. during non active measurements etc ?

Edit: sorry this is mentioned there couple of messages earlier Emils trial - how did I miss that :)
Is there some restrictions for the attachement, cannot open that ?

Esa's picture
Emil is the attachement

Emil is the attachement available, I cannot access it, cannot open, read - I get following error:


You don't have permission to access /d/uploads/usbpower.sh on this server.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

Paul's picture
Forbidden error opening attachment

Try this link instead:

For security reasons, the web server is configured to not allow downloading of shell script files. I renamed it from usbpower.sh to usbpower.txt so you can download it now.

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