Battery Uptime

[jondallimore]

Hello,

I'm testing a battery with a pi 3 - intention is to run it flat and see how long it will power the pi for.

Is there an easy way to see uptime on the pi AFTER the battery dies and I plug it into the mains again?

[diogen151]

Create a .sh procedure that will append (>>) output of "date" command to a previously created .txt file.
Also, create a crontab entry calling that .sh procedure every 10 minutes or less.
First and last entry into .txt file should be measured time period.
After rebooting you have less than 10 minutes to check file to avoid appending false entry.

[W. H. Heydt]

Create a .sh procedure that will append (>>) output of "date" command to a previously created .txt file.
Also, create a crontab entry calling that .sh procedure every 10 minutes or less.
First and last entry into .txt file should be measured time period.
After rebooting you have less than 10 minutes to check file to avoid appending false entry.

Add a sync command after every file write to be sure that the data goes to storage and doesn't sit around in memory where it will be lost when the power drops.

[deepo]

Create a .sh procedure that will append (>>) output of "date" command to a previously created .txt file.
Also, create a crontab entry calling that .sh procedure every 10 minutes or less.
First and last entry into .txt file should be measured time period.
After rebooting you have less than 10 minutes to check file to avoid appending false entry.

I'd suggest adding output of uptime command along with output from date command, otherwise you may have trouble finding where a reboot has taken place.
If you set this to run every 10 minutes then you could squeeze in a few reboots in those 10 minutes and not be able to see that it happened.

/Mogens

[deepo]

uptime.sh

Code: Select all

#!/bin/bash
echo $(date) - $(uptime) >> uptime.log

You may have to add a full path to where the log is to be.
Don't select a place that gets wiped at boot.

uptime.log

Code: Select all

Mon Oct 21 06:32:38 UTC 2019 - 06:32:38 up 9 days, 23:47, 1 user, load average: 1.05, 1.03, 1.05

I don't have a Raspberry Pi here, but you can get help on creating crontab entries here:
https://crontab-generator.org/

/Mogens

[clicky]

Hello,

I'm testing a battery with a pi 3 - intention is to run it flat and see how long it will power the pi for.

Is there an easy way to see uptime on the pi AFTER the battery dies and I plug it into the mains again?

Running battery flat is usually a bad idea (for the battery). Maybe you should get something like https://www.adafruit.com/product/4226 and when you detect (save!) low voltage on the battery side do clean shutdown. Anyway - that's just an idea

[jondallimore]

bash script with cronjob works.
running the battery down is fine, it has protection built in.
thanks

[RaTTuS]

sudo apt install uptimed

[wildfire]

running the battery down is fine, it has protection built in.

But does your storage device?