This topic has 13 replies, 2 voices, and was last updated 5 years, 5 months ago by 
.
- Posts
Hello,
So I have finally completed my build encountering numerous issues. Now the base robot from SDR is having some trouble. It has worked perfectly for the past three months.
1. The battery is constantly going to undervolt and I cannot sustain prolonged operation of the robot. I am not sure if the batteries are not charging correctly. The charger does go from red to green when it is finished charging but they are not holding the charge. Have you guys encountered this issue before? How do I troubleshoot it? These are my batteries got 2 of them…K2 25.6V LiFePO4 Battery Pack 9.6Ahr. The undervolt is at 28V and when I fully charge the battery it levels of at 29V. However, the discharge is rather drastic.
2. The Roboteq MDC2460 is not saving updates. It is weird, so it actually saves the changes I make to the controller in regards to Motor 2, encoder 2, but it does not save the changes I make to encoder 1 and motor 1. I am not sure what is going on here. Have you guys seen this before? I am going to call roboteq later today.
3. I have attached the encoders using the pullup board and the connectors straight to the roboteq motor controller as per your instructions. One of the encoders gives output while the other gives just an output of 1. This may be related to my second question as well.
Any help will be appreciated. I am also available to chat on the phone. I need this guy up and running for a demo asap.
Tyagi
Hey Tyagi,
Have any modifications been made to the robot since you received it? If so, please send pictures.
I would disconnect the battery not holding a charge, and test with one battery. Let us know what the results are.
Hey, Thanks for getting back.
I did not make any changes to the wiring the robot came with. I have added a shell around the base robot which is the biggest modification. I am not sure which battery is not holding a charge. When I checked the batteries voltage both report 28v.
I just did. It still shows 28.2V and reads as undervolt on roboteq roborun+. I will charge one of the batteries to see how it works.
possible that its a bad connection at the roboteq battery input terminal or bad ground. make sure everything is tight and clean connections.
All the connections seem to be proper. A lot of them are glued on so they have not moved from their location especially on the roboteq. The single battery is doing exactly the same thing. The charge is at 29V after charge and it quickly discharges as I run the motors in a few seconds and drops down to 28.1V then the motors slow down then stop. I can try it with the other battery alone but I think the result will be the same.
please try the other battery. if trouble continues, it may be necessary to remove the hot glue around the connection at the motor controller. sometimes if it gets real hot, the glue will seep into the connection and cause a bad connection.
what are you considering discharged? the batteries are not discharged until <22V. They will drop very quickly from 28V with nominal load. The are 25.6V batteries. We have never had an issue with these batteries. We have had 1 12V one fail in 8 years. The likelihood that you have two that are no go is extremely unlikely. You need to troubleshoot the wiring, terminal blocks, or switch, etc. and see where the voltage is dropping out. use a voltmeter, not the RoboteQ voltage reading from RoboRun.
Well when the voltage reaches 28.1V it kinda dies. So technically not full discharge. I have a voltmeter will run some more tests.
So I ran an experiment where I reduced the under-voltage limit from 28v to 25v and the motors run for a lot longer. This means that the under-voltage error is causing the motors to sputter and stop. So it goes from 29v to 28v in a few seconds…That does not seem normal. I will continue to check the wires.
Why on earth are you setting the under voltage limit to 28V???!!! The motor controller is doing exactly what it is told to do. Its a 25V nominal battery. The voltage is going to drop rapidly from 29V since it is a 25V battery. Why did you change the settings and not tell us? The battery has low voltage protection, so that should not be used! Its only used for cheap batteries that do not have internal protection. You should set the value to 0V. This whole thread of questions could have been avoided if you mentioned that you changed the settings in the motor controller.
Honestly, I never messed with that setting. I discovered it when this problem came up and I was digging into the controller. You have just clarified my conundrum with the issue. So it is definitely not a battery issue, but a Roboteq motor controller configuration saving issue.
I cannot save my changes to the controller and yes I do hit save it to controller button every time. I am talking to the Roboteq tech support and they are slow as always.
Thank you for your help. Apologies for the dumb question.
You must be logged in to reply to this topic.