We are having some power issues with our rover. We are currently using the autonomous kit with the 4xAA battery pack. When we put brand new AA baterries in, we can get about 1 minute or so of good run from the servos and motors until the board resets. The time between resets then gets smaller until the robot is almost unusable. It seems to be a current issue with the batteries, so we are wondering if there is a better way to design the program or use a better power supply so the program can run without resetting? We would prefer to leave our code the way it is right now and find a better power supply, but we would like to see what you recommend. We are very disappointed with the performance of the Rover at this point because it is not practical to swap out AA batteries every minute to keep the robot running. Any help/advice would be very much appreciated.
Just curious as to what the specific benefits of changing over to the Pololu motors would be.
I am having the same reset problem after a minute or two of use following installation of new alkaline batteries, and I see from this and other threads that this is not a unique issue. The rover appears to run and respond more effectively without resetting if I have the usb connected, but the problem appears when I go to battery only. This looks like a current limitation issue caused by the motors, as everything works perfectly, but only if I use fresh batteries (duracell 4xAA). I am using the basic kit, with an IR receiver connected to pin 11, and running the WASD sample code (just edited to evaluate the input of the corresponding IR codes received instead of the W, A, S or D character sent). Do you think this issue might be corrected by replacing the FA-130 motors included with the gearbox with lower current Pololu 6v brushed dc motors (the ones with a stall current of 800mA)?
My assumption was the motors on the rover are wired in series, so each sees half the voltage… so for example the original 3V motors use a 4xAA battery pack. No? I’ve not tested it with a multimeter to verify that. Regardless, I’ve seen no ill effect yet.
Not quite - the voltage from the battery pack is split, so the motors would operate at 4.8 to 6V. You are correct that this is not the best for 3V to 4.5V nominal motors, which is why the DFRobotShop Rover has a built-in LiPo charger for 3.7V batteries. We didn’t include the 3.7V LiPo pack as part of the basic kit simply because we wanted to keep the MSRP less than $100.
An 8xAA battery pack can provide as much as 12V, which is a bit on the high side for the 6V motors. Tell us how it goes.
The default motors in the Tamiya Twin Motor Gear Box operate at 3V nominal (~2 AA batteries), whereas the Pololu ones operate at 6V nominal. You can run the originals at 6V, but it’s less efficient.
We can’t seem to reproduce your problem, but we will do a little more testing. In the mean time, are you able to measure the current consumption of the robot while it is running? You can disconnect one end of the battery and instead use a multimeter to complete the circuit. Use your multimeter on the highest setting first, and then reduce if you can.
Hi,
Can you tell us what brand and type of batteries you are using? Alkaline, NiMH, or other? Also, are both your servos of the compound eye continuously moving? Have you added any other components to your robot?
While the motors and servos do consume a fair amount of power, having problems after 1 minute is unusual. If you could post your code, we would like to do some tests. One easy fix would be to use a larger battery, such as this 6000mAh Lithium Polymer Battery.
Thanks,
Thanks for the additional information. We will look into this further and get back to you by early next week.
Sorry I did not see this earlier. I have not been able to test the current consumption yet, but I will see if I can set up a test for that. In the meantime, I did get some rechargable NiMH batteries and ran the same program with those. The performance was slightly improved, but the robot still began to reset within 1 to 2 minutes. I would like to offer this course again in the summer semester and I need to determine if this robot will be a practical solution for my course. I need to figure this out soon so I can order the robots we will need for the course. Thanks again for your help.
We are using Alkaline at the moment, but I would like to try some NiMH as soon as I can get some. Yes, we are moving both servos simultaneously and almost continuously. There may be some pauses, but it is pretty constant motion. We have not added any additional components to the robot, we are just using the parts that came with the autonomous kit. We currently have the Ping sensor disconnected, though. I don’t have the code at the moment, but I could post it later if you would like to look it over. Thanks,
Chad
I attached the code we are using. As you can see, we have adapted the code from the Mr. General example to work with our setup. Thanks for the help