Overcurrent, Main battery low warnings and M1 driver fault

[gsivaych]

I'm using a 2x30A RoboClaw for my differential drive robot, motors have a stall current of 15 Amps each, 2400 qppr encoders. Commanded in Packet Serial Mode from Arduino, PID auto-tuned using BasicMicro Motion Studio. Problems i've come across are -
1). When robot in air (free wheels), Continuous Over current warnings for both motors while running at full throttle, or momentary over current warnings when sudden acceleration.
2). When on ground, i get Main battery low warning with above, while the battery is quite charged. I also get M1 driver fault many a times when going above certain speed or when i try to accelerate faster.
Battery used is 14.8V Li-ion, and can supply upto 30Amps. Cut-off voltage was set to 12V (tried changing to 8V, still no luck).

[Basicmicro Support]

Sounds like false warnings/errors, possibly caused by noise but more likely something specific to that Roboclaw boards.

1. What are the readings in Motion Studio for the current on both channels when running in air?

2. when the wheels are under load what are the main battery voltage readings(not the actual voltage, what the roboclaw thinks the voltage is)?

3. Check the voltage on one of the 5v pins of the Roboclaw while running the motors. Is it stable at 5v or is it all over the place(which would indicate a hardware problem with the regulator).

Do you have the specifcations for the motors you are using? Manufacturer and model numbers?

Is anything else attached to the Roboclaw(rc receiver for example)?

[gsivaych]

1. When in air, current readings stay in 5 amps to 6 amps on normal speeds, direction change gives spikes to 15 amps. Full throttle reads continuous 15 amps for a while then back to 6 amps or a bit above.
2. In general RoboClaw reads 1V less than digital voltmeter, when wheels are under load voltage readings (as per RoboClaw) drop to as low as 8 volts.
3. I got a stable/fixed voltage reading of 5.02V.
Motors : M5-RS555-12 by BaneBots. http://www.banebots.com/product/M5-RS555-12.html
NO, RoboClaw is only connected to Arduino Mega (S1, GND, S2, GND), and two quadrature encoders (1kOhm pull-ups).
Manually tuning PID for velocity response of both motors at given max. speed and acceleration seems to effectively reduce warnings and error. But increasing max. speed or acceleration or introduction of extra load brings them back.

[Basicmicro Support]

Are you doing these tests while using the Position PID control? If so stop. Go back to PWM settings and run the tests on the motors from there. If the Position PID is tuned badly, when the motors are stopped they could end up pulling more current than expected.

15amps when changing directions aggressively with a 15amp stall motor sounds reasonable. But 5 to 6 amps under no load is not. According to Bane bots this motor should have a no load current of around .4amps. I assume you have wheels on the motors? Are they rubbing? Are they hard to turn manually when the robot is not powered? Im assuming you are using Banebots gears.

Confirm the excess current wasnt caused by the Positon PID control.

The 1v less main battery voltage than actual is normal. You can adjust that in General Settings now to compensate for the error(Voltage offset settings).

Your battery is undersized or has a problem. A 4cell(14.8v) lipo battery should never drop to 8v under load. The odds are it is dropping further and you just dont see it in the display(not updated fast enough). The odds are this is contributing to the problems you are having.