New SMC MotoMonster problem

So I got my issue resolved last time, but now I am seeing something new. I am testing the pots on the motomonster driver using the SMC3 setup manager. I am getting clean readings from the pots and they are working great, as is the motor attached to socket 1. Socket 2, however, does not seem to want to run in reverse. When I adjust the pot it will start when I get out of the deadzone, but if I turn in the opposite way, both lights come on on the driver next to the socket indicating it is trying to drive the motor both directions at once.

I do not see any shorts, and I have tried different pots and motors with no change. Any ideas? Thanks!

Another crap Chinese Monster Moto by the sounds of it. The VNH2SP30 chip shorting out internally.

Typical these days I'm afraid

That is not what I wanted to hear. I just spent over a month waiting for this to get here from Dxsoul. If I don't have a motor on it, the light switches fine, its just when there is load on it.

Typical behavior, typical issue, under load the MMs are just crap. Sorry mate, no good news but decades before we made our own (same) experiences lol

Thanks for the info. Im going to try a new one. If that won't work ill have to bench my build for a few months to save for some better drivers.

Hi mate unless you buy the real deal you run the risk of bad ones, search my threads about MotorMonsters I have had a lot of bad ones and I mean a lot.

@noorbeast will be able to point you in the right direction , he's our FAQ guru

Yip, the replicated MMs are very unreliable. My first one had the exact same issue so I had to wait a couple of months for another pair to arrive. Unlucky

Soooo, new mm, new possible problem. I got everything wired back up and everything is responding fine in the interface. When I turn the pot to test, the motor comes on as usual (both motors, both directions work this time!) but after about 15 seconds the motor shuts off until I return to the deadzone. If I power the motor back on either direction, it stays on for about half the amount of time it did before, until im lucky to get a 1/4 turn. The temp on the mm is about 50c, and I read that they are ok to 150 so I don't believe that is the problem.

Is there a setting I may be missing, or am I the recipient of another bad board? I can upload a video if that might help.

Unfortunately sounds like bad MM - its a real lottery . I had similar issues as @SilentChill - ended up changing out bad chips for serviceable ones. FI. Pololu have what seems to be real ones for $10 each https://www.pololu.com/product/537/resources. Not exactly a simple job though and can get expensive when you want 4 for each motor - lucky I only needed 2 for the whole rig. They also have their own version https://www.pololu.com/product/708 but once again not cheap. But may be worth it in the long run if just for the reduced hair pulling .

Sounds like another crap chip, try on either side see if it's just one of the chips that is faulty. If you can do this then as @SeatTime says you can swap out chips, not to hard to do with a steady hand and a heat gun. Unless you have a reflow station then it would be simple.

I think I discovered the problem this time. Further research shows that the motors I got (wheelchair motors) are actually 24v motors. Trust me, I feel like a fool for just now figuring it out. Would this have caused the behavior I observed with the mm shutting down?

If I stick with these motors, I am looking at https://www.pololu.com/product/2507 for powering them. Do you guys have any experience with these? Also, is there any wiring diagram I could use for connecting this to an arduino?

Thanks a ton for all your help so far. Sorry I am such a noob at this!

*update *
I attached some 12vs for testing. Same thing is happening. I think I am going to look into a totally new option, as these things are just a headache. If anyone has experience with the pololu I'd really appreciate input.

@Scotty1186 Are you using one MM for two Motors ,,,, If so try using two MM ,,one for each Motor and see if that makes any difference.

Good idea, but after discovering that the motors are 24v I am going to be upping to a bigger controller rather than pushing the mm. I can still refund both junk ones so ill be doing that to pay for it. Thanks for the advice!

In regard to the Pololu VNH 5019 - this concerns me from their website.

1 While the overvoltage protection typically kicks in at 27 V, it can trigger at voltages as low as 24 V, so we do not recommend using this motor driver with 24 V batteries, which significantly exceed 24 V when fully charged. If the shield is configured to power an Arduino or Arduino clone, the supply voltage must conform to that Arduino’s input voltage requirements.

I have used these drivers in some testing but never really in anger as I could not get the right 24v motors locally, so ended up going with 12V ones. My concern would be back EMF pulses under big load, which could trigger the drivers overvoltage protection. Maybe some big capacitors could lessen this. For 24V motors I would also look at the sabertooth drivers. https://www.dimensionengineering.com/products/sabertooth2x60 - other members have used these - although they are not cheap.

In more ways than one. Sabertooths are somewhat expensive but you don’t have to worry about receiving crap for your money either. So you can feel like this instead of like this .

BTW the 2x32 in most cases is more than enough, the current peak is up to 64V which is a lot. This driver costs around $124 and supports voltages up to 36V! The 2x32 has an usb port and 115200 baud (not by all Saberthooths supported). Easy to manage, I am very happy with it

Last but not least the driver is unbreakable, and if something is going wrong Dimensions Engineering will replace it the first year without charging any fees:

"Dimension Engineering offers a full 1 year manufacturer's warranty. If any product fails within one year of the purchase date we will replace the product at no charge.

After 1 year we will either repair the item or the item can be replaced for 50% of the retail cost.

Should you order the wrong product, we are willing to exchange it for the correct product for the difference in price. There is no restocking fee"

All good! I got the new Uno and got everything hooked up. I discovered that I had the 5v on the pot hooked up to the wrong port instead of the VDD. I made that correction and it works great now. Can't wait to get it hooked into the real motors. Thank you all again for your help!