Current consumption of Magni robot with no load

General Questions
1

Hello posting the question here if anyone has any information.

Does anyone know what is the current load of the Magni on the batteries if made to run normally (perhaps back and forth about 2m distance)?

How can I go about measuring this, besides attaching a multi-meter between the batteries and the motor board and following it around?

2

There’s a ros topic you can echo called “battery_state” of type BatteryState which gives you data on voltage and percentage. I don’t think it has a current reading though, so it’ll be hard to measure average consumption directly.

3

Because of the sometimes large spikes in current it it best to measure the current usage with a clamp on DC amp meter. I have tried to do this for you but have found my meter to be non-functional now so I have ordered a new meter.

I hope to have your question answered by Monday and I will measure in a few different cases to better help you understand what effects the current usage.

4

I had this long ago but never documented it. I will make this show up on our learn pages most likely in discussions about battery types but for now here you go:

When you first turn on the Magni with charged and healthy batteries and the motor power off the Magni uses about 0.45amps (mostly steady)

When you enable motor power and drive the Magni around at about 0.5 Mps the robot uses 0.8 - 0.9 amps (some fluxuations in that range).

If you stop the Magni with motor power enabled after usage it will sit at about 0.7 amps.

Hope this helps,
Mark

5

Hello!

Thank you for your reply it is very helpful. I found your post on this from last year with some interesting findings at quite a high speed (1 m/s ), ill put it here for reference.

Seems like if I am driving the Magni 0.5m/s with no load, I should expect 0.8 to 0.9 amps current draw (with some fluctuation).
But if I am driving it at 1m/s with 4.5kg load on each wheel, I should expect 1.5 to 3 amps (wow fluctuations peaked at 5amps) current draw.

It would be helpful to have a current draw to torque and current vs speed graph of the Magni, do you happen to have that :grinning:?

6

Since you asked this and I replied here I had also updated our page that discusses batteries with a table now and it can be seen here: https://learn.ubiquityrobotics.com/need_to_know
This page if you have not seen it has had much of the info on battery selection and other things useful to know for Magni owners.

No we don’t have a breakdown in the form of detailed graphs.

I thank you for your question on this post because it is questions like these that constantly lead us to improve our documents on our Learn pages when I realize from questions like this post that we are lacking important documents to help customers better make decisions (in this case how big should I get my batteries).

If you do not have it bookmarked already, our Learn site is in fact our ‘Manual’ for both usage and support and expansion.

thanks,
Mark