16 replies to this topic

[Shoopy]

Hello all. I have a problem. Here's what I am trying to do: power a tank with a portable air compressor.

I have everything basically done. I have a air compressor, tank, on/off button, and 12v RC battery. I am just having problems with connecting the button.

Every time I have tried to connect the button to the compressor and battery together, the unit doesn't work and the wires start to smoke and burn.

I know there are a lot more people that are far more advanced than I in the field of electricity. I am hoping one or a few of those people know what I am trying to do and can offer some advice.

So, if you could help me out my drawing a diagram or just explaining how I should sodder these wires that would be wonderful.

Thanks a bunch,
Shoopy.

Edited by Shoopy, 22 May 2013 - 03:52 PM.

[Shoopy]

[rego]

Your second attempt made the switch completely useless, if the switch is single pole. The first attempt should be working, unless you hooked the positive of the switch to the negative of the battery. There may also be a short in your compressor or switch. If you have a voltmeter, attempt to see if either of them are faulty. Or just try running the compressor from another source of power to see if it works.

Edit: Make sure your battery can supply enough volts and amps for the compressor.

Edited by rego, 22 May 2013 - 04:20 PM.

[Shoopy]

Your second attempt made the switch completely useless, if the switch is single pole. The first attempt should be working, unless you hooked the positive of the switch to the negative of the battery. There may also be a short in your compressor or switch. If you have a voltmeter, attempt to see if either of them are faulty. Or just try running the compressor from another source of power to see if it works.

Edit: Make sure your battery can supply enough volts and amps for the compressor.

Ok thanks a lot! I will recheck everything out. Do you know what kind of button or switch I should get, like a certain type or maybe a link. Thank you.

[rego]

All you need is a simple switch with two terminals for on and off. Your wiring may also be to small, but that's not as likely.

[snakerbot]

positive of the switch

No such thing. What is possible is that he wired the positive of the battery to the positive of the compressor, which would certainly do bad things. Your pictures seem to indicate this, with the black and red swapping at the battery connector, but that may have been just the picture. Where was the smoke coming from?

Your wiring may also be to small, but that's not as likely.

To me, this sounds like the problem, honestly, as long as you didn't wire the compressor backwards, as mentioned above. Smoke and burning means heat, and heat means resistance. What gauge is your wire? What current does your compressor draw?

[azrael]

"the unit doesn't work and the wires start to smoke and burn. "

derp here's your problem. Use thicker wire and a higher rated switch.

[Shoopy]

Ok. I will check my wiring. I will rewire everything with a thicker wire. I do know that the wiring for the battery is much thicker than the wiring that came with the compressor.

Will the people at radio shack know if I take my old button and ask them for a "higher rated switch."?

I don't know how much this picture will help but here...

Edited by Shoopy, 23 May 2013 - 08:11 AM.

[azrael]

It should say on the packaging. Something like Rated for 2A.

[Hammy]

The 1st attempt seems correct, but swap the red and black connections at the battery .

The 2nd attempt, if you on the switch, then the battery will be shorted out and the wires between the battery and switch, and the switch will conduct masses of current, and get hot and catch fire ad a result. So that attempt is a NO NO. And maybe you have f'd your battery. So better get your battery checked to see if ok or not.

As a guide to thickness. Your wires should be as thick as the ones from the battery, and I guess the switch rated at 2 amps. But to advise properly, I would need to know the power consumption of the compressor and battery voltage

Edited by Hammy, 23 May 2013 - 03:12 PM.

[Shoopy]

I currently have the battery connected to the compressor directly with no button. When ever, I connect the plugs, the compressor still work. I'm guessing I didn't do anything terrible to the components yet because they still work.

[Hammy]

I just see your piccy. That switch seems a little weedy. Get one that can handle 1-2 amps. It will be bigger and have bigger terminals.

The one you have pictured is probably good for 100-500 mA.

[azrael]

It also says the switch's rating on the side, should be indented into a the metal plate portion.

[Shoopy]

Just picked this up. I believe that is was my wiring. I WAS using 18 gauge, now I have 14. And the new switch I got says its rated 16 A at 12VDC. Testing now...

[boobie817]

In both pics you switched the wires at the battery connection. It would be Positive to positive and negative to negative. The first diagram will work after you fix that

Edited by boobie817, 23 May 2013 - 08:29 PM.

[roboman]

It's neither the switch nor the wire. 18ga wire can handle a LOT more current than you're ever gonna draw with a little motor like that. You're looking at 3 amps, 5 maximum, but likely even less than that. If the wire was too small, it would melt (I've done that), but the motor would turn very briefly. Since the motor appears to be the same as one on the compressor I took apart to mount on a robot earlier today, it's probably an RS-540 size motor. And, since it's a DC brushed motor, connecting it backwards will just make it spin the other way, which isn't an issue here.

18 gauge wire is rated for 16 amps, by the way. The only way you're hitting or exceeding that is if you're physically stalling the motor.

I've got that same pushbutton, and it can handle much more current than the package says. As it is, it's rated for 3A at 125V. That's plenty for this application - if that motor is drawing more than 3A for a significant period of time, something else is seriously wrong with your system.

The reason your wires melted when you tried it is because you shorted out your battery in the second setup. You basically created a very big fuse.

Now, there's a chance the compressor could be protected against reverse polarity with a diode of some sort. That's somewhat unlikely, but certainly a possibility. Try hooking red to red and black to black, like you're supposed to do anyways. Even if it doesn't fix your issue, it's a good habit to be in.

Check your compressor without the switch by touching the leads to the terminals in the battery connector. It doesn't matter how you hook it up, so long as you don't short out the battery. If it doesn't run like that, then you've either got mechanical problems or just a bad compressor.

[Shoopy]

Roboman, I think I understand everything you said. In the first attempt, one the button would work to turn it on and when I went to turn it off, the compressor still worked but it was much slower. The second attempt, my wiring just smoked and burned and everything.

OK thanks to everyone who helped!

In the pictures, I made the mistake of drawing the positive and negative wires switched. It actually wasn't like that.

I rewired with the new wire and installed the new switch. Everything works flawlessly.

Thanks for all the help.