We observed some strange behaviour with our Spike relays today. I was unable to find any threads describing symptoms similar to what we saw.
With the Spike in the “Off” state, we observed the LED on the Spike was orange and the voltage across the output terminals was 0Vdc.
We energized the Spike with no load connected an observed the LED on the Spike turn green. The voltage on output terminals was about 11Vdc. The input voltage was 12.45Vdc. When we connect an AndyMark 9015 motor to the Spike output terminals, the voltage goes to 0Vdc and the LED turns orange. The M+ terminal is at 0Vdc with respect to the GND terminal. Disconnecting the PWM cable from the Spike does not change anything.
We observed this behaviour with two different Spikes, one removed from a working robot. We swapped the PWM cable even though we seem to be able to control the Spike. One Spike had a 20A breaker. One Spike had a 20A fuse that appeared good.
We checked the wiring and found that the connections from the PD Board are correct and the orientation of the PWM cable is correct.
We did not happen to note the behaviour of the LED’s on the DSC.
Does anyone have any ideas on what we may be doing wrong or what to look for?
My team had the same problem a while ago, but figured it out.
If you take a look at the table in the manual, you’ll see that the am-0912 can NOT be powered by a spike relay. It’s got nothing to do with your wiring or your programming, it’s simply that it can’t be run off of only 20a current.
The table also specifies motors that can be used with the spike, but they’re weaker motors, and thus might not be suitable for what you’re doing.
Zmarken is correct about the rule, but something else is wrong here, because wiring this motor to a Spike with a 20A fuse should work just fine. We re-did our frisbee shooter using this same configuration, and it works fine (“Demonstration Mode” now!)
A Banebots 390 has about the same rpm - but is lower torque…the 395 is a bit faster…still lower torque though. Both can be run from a Spike legally this year.
The indication is that you might have a loose connection somewhere at the input of the Spike. This could be a bad crimp or a poorly made termination at the PD. You could have a bad breaker in the PD or it could be not fully inserted. Or you may simply have a bad PWM cable such that the return line is shorted to something. When you add the load, the input likely falls to below 5 volts or pulls the control wiring to some “off” state. There is also the possibility that the DSC power has a problem. Always check to see if there are three LEDs brightly lit on the DSC. Then check for correct operation of the LEDs that feed your relay output.
Yes…it’s demonstration only - was illegal last year as well, but we had a different configuration for competition - built the current system as pre-season project for new members this fall. It works great, though - in the application it never gets anywhere near stall torque.
The input voltage to the Spike did not change as the motor was connected and disconnected. We put the probes on the input terminals of the Spike so any bad connections “upstream” would have been evident.
Only the output voltage changed. We may have to try it with a lower current load in case there is some current limiting device in the Spike.
Swapping the PWM cable for another one did not seem to change things.
I can also try to measure the current running through the Spike using my clamp-on meter.
There is no current limit that I am aware of other than the fuse/breaker. It is just two SPDT relays between input and output with the drive circuitry connecting to the coils. The input is opto coupled from the DSC lines. The Spike does not have the internal protection from dirt and other crud so it is possible that both of your Spikes have a serious amount of contaminant. If you have a fuse in place, they sometimes look good but actually have a small crack that opens with current. Try changing with a new one to be sure.