Questions about Charging and Power

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1

Hi there,

I’m using a Stretch SE3, and I typically charge the battery using supply mode. However, I usually disconnect the charger for experiments.

My issue is that the robot sometimes shuts down with a beep and no warning, even after being in supply mode for a long time with a green indicator light. Is there a more precise way to monitor the battery status? It’s frustrating not having any signal before the battery dies, so is there a way to predict a shutdown?

Also, what’s the most efficient way to charge the robot for 1-2 hours of experiments without turning it off?

Thanks!

2

Hi @seongwoncho sorry for the issues you are facing, usually the robot should at least turn the light bar red before shutting down, if this is not happening there might be another issue at play here.

Has this always been the case with your robot, where it doesn’t warn you either audibly or visually?
You should also expect with not so heavily used batteries and a high CPU load the robot should last at least 2 hours if you are not getting this runtime or any of the above is true, please email support@hello-robot.com so we can debug even further

You can read the voltage status message to get a better state of the battery level please see example code below
r = stretch_body.robot.Robot()

r.startup()

r.pimu.pull_status()
print(r.pimu.status[‘voltage’])

This will give the battery voltage level, usually around 11 to 10.5V is where I would recommend the robot be plugged into the charger.

For your question about most efficient way to charge the robot while during experiments there is nothing that is supper great but, one option we have seen some groups do is purchase an external power pack like this one here this way you can plug in the NOCO charger into this while in 12V supply mode.

It is not supper efficient as there is multiple conversion steps. Also since the robot is ON only some of the energy would be directed to the battery and the rest powering the rest of the system. But it might be able to extend the run time an extra 2 to 3 hours (depending on CPU load)