@Davidaharrison, I feel very grateful and blessed. There was a lot of loss of life and property in my area from this category 4.9 hurricane. There are still over 1K without power. The area is starting to recover quicker now but things will never be the same around here again. I'm glad you all faired good through Fiona .

Anyway, I don't have a cool schematic like you so I hope I can explain my setup.

Actually I've only used a Sabertooth once without a Kangaroo X2. That was to drive a tread section of a big robot like a tank. With that one I controlled it with a RC controller and the receiver attached to the ST. I powered this one from a set of 12v 32ah deep cell batteries. I was amazed how smooth and responsive the robot was when using the ST in RC mode. I'll add a link to a video below of me testing it.

All the other ST's I used I had a Kangaroo X2 connected, I commanded them using Simple Serial from an EZB's Uart port. I used motors with encoders because I needed speed and position control. In all these cases I used AC to DC converters and 2X32 Sabertooths. The 2X32 is the only ST that can run directly from a power supply without having a dump battery connected for the regeneration power the ST backfeeds. This one has a voltage clamp you can set in the software and use a power resistor to absorb the regen voltage. Elegant.

Like you I don't supply voltage to motors or servos through an EZB. The EZB will brown out if the motors pull to much current.

I hope this helps.

Could you tell me what kind of switch you are using between your battery and Sabertooth?

Dave thats a serious piece of craftsmanship. Here's the Battery Switch.

I may have an idea what Dimesion was meaning, I'm waiting for them to confirm. I think the terminology they used confused me somewhat from the actual issue.

I'm wondering if the internal rail on the board between b- and 0v is somehow current limited maybe in relation to how the BEC works. If that's the case maybe the parallel path to ground resulted in too much current through the BEC side of the circuit?

Thought I was on to something with it being caused by the parallel path to ground through the 0v exceeding the current limited for that track of the board.

However the response back has me a little confused. I fail to see how adding a ground loop could increase the potential that the BEC side of the sabertooth would see. If there's resistance on the ground loop would that not increase the potential on the b- rail which would decrease the potential as it would now be sitting above 0v?

Anyone able to explain to me how this could expose it to 24vdc?

It sounds to me like they are wanting you to separate the 24v battery neutral from the 5v grounds. Looking at your sketch I don't see how you can do that. I guess I'm not smart enough to see it. That or add a opto isolator on the logic side of the ST.

My issue is they are saying that the ground loop can cause the BEC side of the circuit to see 24vdc. I don't see quite how this is possible. I thought the loop could expose the 0v track to a current max that it was not designed for, In my example above it would be half the 25A max current, potentially 12.5 A depending on resistance.

I'm not quite understanding how the loop could cause the logic side to see 24vdc

I’m super confused by their message. All grounds need to be connected. The grounds of all power sources. Can you ask to speak with someone more senior there?

He's back up and running, Connected without the extra cable from Saber ground to the Arduino. New Control settings for max spin work great, I have that tweaked up above the max speed setting and I think now I have the right balance that I feel comfortable with the kids controlling him. Thanks again for all the help.

https://www.youtube.com/shorts/n-6u3uXuWeA

Don't know why but the embed youtube isn't working for me, but here's a video of some moving around in the basement. Now to find the time to program some new actions, just under 2 weeks to go.

That's awesome to hear! Unfortunately, youtube shorts don't embed. It's their way of getting people to visit the website rather than be embedded on a 3r party site.