We have ran some tests with different robots and battery configurations to understand the continuous run time given a specific compute load. All tests were run using this command below
roslaunch Stretch_navigation mapping.launch
This package has a decently high compute load on the batteries, and is a good example of what some users might run while using Stretch. The table below shows the difference between a Stretch RE1 with Unhealthy batteries compared to a Stretch 2 with Healthy Batteries.
| Testing Parameter | Stretch RE1 with Unhealthy Batteries | Stretch 2 with Healthy Batteries |
|---|---|---|
| Stretch Run Time Duration | 1hr 23 mins | 2 hrs 56 mins |
| Voltage Level Cutoff | 11.65V | 9.5V |
The minimum run time you should see on a Stretch with unhealthy batteries is approximately 1 hour and 23 mins, please keep in mind this is using a benchmark testing procedure which should represent the majority of continuous use applications.
Voltage Level Cutoff
One of the testing parameters we have is voltage level cut off. This voltage level cut off ranges from Max:11.65V to Min: 9.5V The reason for a voltage cut off on Stretch’s power system is to ensure proper longevity of the batteries, by not making them run extremely low and permanently damaging them.
One thing to note as you can see from the Stretch 2 Healthy batteries curve, the rate at which the battery voltage decreases when it reaches 11V is extremely fast, approximately 8 minutes till the robot shuts off. Our recommendation is whenever you hear the low voltage buzzer go off please plug in the robot to the charger using supply mode immediately to ensure no abrupt shutdown.