Well this sucks. Swapped the new boards in and same problem. Runs for a few seconds and then shuts off. The power lights on the relay boards click off and it takes a few seconds for them to click on. Got a few thoughts.
First is maybe the wiring is wrong. When in forward, only one of the LED lights (there is one per relay) clicks on (board 1 relay 1) and both motors are driving forward. It dies quickly this way. Switch to reverse and then LED 2 on board 1 lights up along with LED 1 on board 2 but only the motor connected to board 1 spins. It takes a lot more effort to shut down this way but it does shut down eventually. Im wondering if one of the butt connectors I’ve got isn’t allowing a good connection somewhere.
Second thought is maybe the battery can’t discharge fast enough to keep up.
Thoughts?
From your description of how the LEDs are lighting I would suggest to double and even triple check your wiring. It's happened to me on more than one occasion. The way the LEDs should illuminate is for forward LED 1 board 1 and LED 1 board 2 to be on. For reverse LED 2 board 1 and LED 2 board 2 should be on. By the way, the relays aren't really doing anything when going forward since the normally closed position supplies power to the motors. Which brings me to my suggestion. If I understand your description correctly, only one LED is coming on in forward when there should be two. If that's true then something is seriously wrong. Either bad wiring, a bad LED, bad optocoupler (on the relay board), or a bad relay. I'd check with a multimeter without the motors connected to see that they function properly.
As for it shutting off, it could be the battery. Is it new or old? I read the specs on it and it's rated for 7Ah, which means that it can supply 7 amps for one hour. I also read that these motors combined together can draw upwards of 30 amps under load. So depending on the condition of the battery and how much current it can supply it might be the issue. Have you felt it getting hot when it shuts down or have you measured the voltage of it? You could always temporarily use one of your car batteries so you know that won't be the problem.
Another thing it could be, but I highly doubt, is the motors are shutting off. The window motors in our trucks have a thermal switch that will open when they draw too much current and get hot, then after they cool down they work again. Again, you could check the resistance across the motor leads when it shuts off (need to disconnect one lead from the relay module first).
If you want me to go over how you physically have your relay modules wired then get a clear pic(s) of the wiring and I'll do my best to read it. Also, the relay modules you have now - are they exactly like the ones in the link or are they red like the 10A ones in your previous post. If they're different than the link then a pic of that too so I can see the pinout.
