I think my new 15A Roboclaw has a problem

General discussion of using Roboclaw motor controllers
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ChrisA
Posts: 23
Joined: Mon May 22, 2017 4:32 pm

I think my new 15A Roboclaw has a problem

Post by ChrisA » Fri Apr 13, 2018 6:19 pm

I have the 15 amp Roboclaw. It has been in the box for a while and now I try to use it. It seems not to work.

When I connected to IonStudio I notice the firmware needed to be updated. That went OK. Firmware is now 4.1.24

Connections: Very simple just this...
(1) A 1 amp linear power supply that has an internal 1 amp circuit breaker (this is the "safest" power supply I own) it is connected to the "main battery" screws.
(2) A 9V battery connected to the two LB pins
(3) A USB cable going to a PC running ION Studio

At first all is well I can read the voltage of both batteries and they are correct.

Then I move one of the PWM motor control sliders off zero and the breaker on the main power supply trips. Nothing else is connected, no motor and nothing on the 0.1 header pins other then the battery. After the breaker trips the logic battery is still working so I can switch to the General Status Page and see the following
(1) voltage on the main battery and it is zero
(2) both motor currents show as red and there is a red indicator on the M1 driver fault

This is 100% repeatable. I can do a reset and the status goes to green then if I move the control off zero the breaker trips again.

I can't believe that the Roboclaw can't work with no load attached.

I thought it might be as simple as a solder bridge but an ohm meter does not show a short across any of the screw terminals.

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Basicmicro Support
Posts: 1272
Joined: Thu Feb 26, 2015 9:45 pm

Re: I think my new 15A Roboclaw has a problem

Post by Basicmicro Support » Mon Apr 16, 2018 9:59 am

1. remove the 9v battery. Im assuming this is on eof the small square batteries. Its probably not helping and may be causing problems(voltage drop under load, very little power etc) so remove it to simplify the setup.
2. You dont say what the 1amp power supply voltage is.
3. What revision of the Roboclaw do you have. It will be printed on the PCB. Something like V3,V4,V5 etc...

Under normal conditions the Roboclaw shouldnt have a problem running no-load. The fact the breaker is flipping could indicate something is damaged. Or it could indicate the power supply is very sensitive. Even under no load it takes power to switch the mosfet gates. This could cause spikes high enough to trip a 1amp breaker(Im guessing here since I've never tried to use a 1amp supply with a breaker). My guess is if it really is a 1amp breaker(eg opens at 1amp) it must be very sensitive.

If you have something bigger I'd run that instead. Test both channels one at a time. If the problem only happens on one channel then the odds are something is wrong with the Roboclaw. We warranty our products so if something is wrong with it it will be repaired or replaced.

ChrisA
Posts: 23
Joined: Mon May 22, 2017 4:32 pm

Re: I think my new 15A Roboclaw has a problem

Post by ChrisA » Mon Apr 16, 2018 12:33 pm

The version is "V5D"

I've tried a larger power supply. I have an old power supply from an old PC that can supply up to 16A at 12V. It trips too. But the circuit protection takes some number of minutes to reset

I use the 9V battery because without it I loose power to the logic when the power supply fuse or breaker trips and the USB device disconnects from the computer. The small battery does a good job of powering the logic. Your software is useful for diagnosis but the roboclaw needs power for this, so the battery is used.

I can try another test with a resister in place of a motor. Something like a 100R would draw a small current.

The Roboclaw Windows software shows some minor motor current even with the PWM sliders at zero. A few milliamps and it flickers to fast to read. I figured this is noise the ADC but as soon as the slider goes non-zero the current shows and over limit and the power supply fuse blows. I got tired of replacing fuses so I found this supply that has a breaker.

I will send the unit back for diagnosis and repair if your suggestions don't work

Thanks,

Chris

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Basicmicro Support
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Joined: Thu Feb 26, 2015 9:45 pm

Re: I think my new 15A Roboclaw has a problem

Post by Basicmicro Support » Tue Apr 17, 2018 11:38 am

The 9v battery is not recomended because based on past experience 9v batteries are pour power sources. The roboclaw will power itself from the main power source just as well. If the board is shorting itself out with a bigger power supply then it most likely has a problem. If it happens when you start a motor channel that would indicate one or more of the mosfets on that bridge are damaged. Its not something we would see under normal operation so something must have happened from the point it went through testing till you received it.

If you send it in we will determine the problem and repair or replace the unit.

Ship; it to the address on our Contact page and include you return address and contact information in a note inside the package.

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