Current reversed on compressor spike controller

[Mike Betts]

Scott,

Last year's rules allowed you to replace the 20A fuse with a 20A self-resetting circuit breaker because everyone was having this problem.

The issue is that, as the battery voltage goes down, the current to the compressor goes up. The mechanical work that the compressor is attempting to do is independent from the drive system (or anything else) on the robot. If the mechanical power remains the same, the electrical power will remain the same (neglecting efficiency) and the current must go up as the voltage goes down.

Replace the fuse with a circuit breaker and move on...

Mike

[sanddrag]

While your at it, you should verify that your compressor is not running in reverse. Symptoms can include extreme heating (to the touch, it feels very hot after running for a little while) and a prolonged time to reach full pressure in the tanks. Running the compressor in reverse has the potential of drawing more current and it's efficiency goes way down. It could eventually lead to failure.

The reason I mention this is that I have seen it too often.

[mechanicalbrain]

THIS IS A UPDATE. No nothing like that. I'm updating for Scott. We know its not the compressor (I got it running on a 9 volt) and its not the spike, battery, fuse, wire, or pressure sensor. The spike is literally not receiving a signal. In fact nothing connected to the relay is getting a signal. I'm wondering if their is a real easy way to test if the relay works. Chances are its not the code because the compressor stopped working after running fine with no changes to the code. Weird fact: we commented out the pressure sensor code and we got a response from the compressor but all that happened is the fan made a twitch (I'm guessing the motor switched polarity) once every second. I'm completely clueless. I tried switching out every part in the electronics but nothing changed!

[sanddrag]

Try a new pwm cable and a new port on the rc (with code changed for that port). Also, if you can get your hands on an older Spike try that. We had problems with the 2005 ones too (not working, oscillating, etc).

[mechanicalbrain]

Originally Posted by sanddrag

Try a new pwm cable and a new port on the rc (with code changed for that port). Also, if you can get your hands on an older Spike try that. We had problems with the 2005 ones too (not working, oscillating, etc).

We tried 3 diferent spikes (including older ones) , 4 pwm wires, and a number of ports. Im pretty frustrated! The light was a steady orange the entire time. I doupt it could be the code since it gave out on us while we were using it... One thing im going to try is to solder on sewing needles onto a PWM to make sure we get a connection.

[sciguy125]

Originally Posted by mechanicalbrain

One thing im going to try is to solder on sewing needles onto a PWM to make sure we get a connection.

I hope you mean onto a cable and not the controller. I think the pins on the controller are gold plated (corrosion resistant). It would be a shame to get solder on them.

But I seriously think that you should try the meter first (if it's pulsing too fast, you might be better off with a scope). It'll tell you if you're even getting voltage/correct signals. If you're not getting anything at the end of the cable, you should try the pins directly on the controller.

[mechanicalbrain]

Originally Posted by sciguy125

I hope you mean onto a cable and not the controller. I think the pins on the controller are gold plated (corrosion resistant). It would be a shame to get solder on them.

But I seriously think that you should try the meter first (if it's pulsing too fast, you might be better off with a scope). It'll tell you if you're even getting voltage/correct signals. If you're not getting anything at the end of the cable, you should try the pins directly on the controller.

No deffinetely the wire. I need to check the multimeter for a signal though because i honestly can't remember what we got.

[sciguy125]

Originally Posted by mechanicalbrain

The spike is literally not receiving a signal.

If you haven't already tried another spike, do so. But, we had this problem too. It took us days to figure out. You're probably not putting the PWM connector in right. It might go all the way in, but the pins might not actually be in the connector. Sometimes, we would even get only one or two of the pins in.

Just to make sure though, pull the connector out of the spike. Test it for voltage between ground and the appropriate signal pin. It should be a solid 5V. If you have that right, then I probably found your problem.

Actually, I just reread your post...

Originally Posted by mechanicalbrain

we got a response from the compressor but all that happened is the fan made a twitch (I'm guessing the motor switched polarity) once every second

Do the voltage test still to check your code. But also pay attention to the LED once you plug it back in. Orange is off, red is reverse, green is forward. I also think that the spike makes a clicking noise when it changes direction (I can't remember). You might also want to put in a meter instead of the compressor to make sure that it's getting a solid 12V.

[Alan Anderson]

Originally Posted by mechanicalbrain

Weird fact: we commented out the pressure sensor code and we got a response from the compressor but all that happened is the fan made a twitch (I'm guessing the motor switched polarity) once every second.

What fan?

If you're using the standard programming, the compressor is supposed to be connected between the Spike "FWD" output and ground. Is that how you have it?