Kobalt 26 Gallon Quiet Tech Air Compressor trips breaker -SOLVED

I recently replaced my old 6 gallon Central Pneumatic pancake air compressor with a Kobalt Quiet Tech 26 Gallon compressor from Lowes.  I dropped the old pancake compressor and broke the handle and wanted to replace with something a little bigger.  Since I was going to buy a compressor anyway, I wanted the capacity to run air tools. The 6 gallon tank just didn’t cut it.   I found a good price on a Kobalt Quiet Tech 26 gallon compressor at Lowes and took one home (item number 0905518).   I got it home, unboxed, set it up, plugged it in and turned it on.   First impression:  Wow, this thing is quiet!  Surprisingly quiet.  It was not nearly as loud as my 6 gallon pancake compressor.  I could have a conversation right next to it without raising my voice.  I watched as the pressure increase in the tank all the way to 150psi and the motor turned off.  I stood in silence listening for leaks.  Nothing.  So now I prepared to air up some tires, blow some dust, whatever.  (Everything looks like it needs air when your air tank is full).  After putting in a couple extra lbs per tire and cleaning the shop floor I waited for the compressor to kick in and fill the tank back up to 150psi.    The compressor kicked back in and sounded like it wanted to start, but the pistons stopped after a couple turns and I heard an electrical hum.   The lights dimmed and my electric breaker popped.  No lights, no sound, just quiet darkness.   After several attempts to start it up and trips to the basement to reset the breaker, I finally dropped the pressure down to 20psi in the tank before the motor kicked on again and filled the tank back to 150psi.  Again with a filled tank, only a hum and dimming of the lights.

Bummer.   I brought it back to Lowes and exchanged for the same model thinking I had a lemon.  Air compressor #2 kicked on and worked maybe 40% of the time, the other times I had the same issue, always when the tank was already pressured up.   I tried plugging into the wall, into extension cord, into the 6′ powerstrip on my workbench,  with lights on, with lights off, unplugged the fridge, etc…sometimes it worked, but most of the time failed, although I do believe I had better percentage of success when directly plugged into wall.

I called Kobalts hotline and talked to a rep, they said they could send a new check valve but were currently out of stock.  The other option was to get a reference number and return to Lowes.  Feeling totally defeated I took the reference number, but then started reading up about start/run capacitors on air compressors.  It seems the symptoms I had pointed to a bad start capacitor.  I found and took a look at the capacitor.  It’s located under the a housing, directly under the gauges.  The housing is screwed into a flat plate directly on top of the tank.  I looked at the capacitor and noted 250V / 120uF.   It had the number CBB60 stamped on it.  I re-crimped the connectors just to be sure we had a good connection, but had the same issue.   Doing a quick Amazon search, I found a replacement capacitor and ordered it.  Unfortunately I don’t have a capacitor tester, but saw you can find them on Amazon for a pretty good price–maybe next time.  I don’t usually just throw parts at issues…oh who am I kidding?  It’s mostly how I roll.

So….as it turned out replacing with a like-sized capacitor did not affect how it ran.  I was still able to get it to run at full pressure only a small percentage of the time, and it seemed random. Now I’m facing internal turmoil….should I just give up and take it back to Lowes?  But I really, really like how quiet this thing is.  I would have to spend three times what I paid for another brand that is quiet like this thing..  So, before taking it back… more research.

According to several websites, it seems you can increase the uF of the capacitor +/- 20% without damaging or creating issues with the electric motor.  Okay.  So 120 x 1.20 = 144uF.  I could go up to 144uF as long as I keep the 250V.   Okay,  done.

I ordered this:

It’s 250V 150uF (a tiny bit overkill, but all I could find that looked similar in size and shape.  I’m pretty sure this thing will void my warranty, but whatever…that’s what I do.

When the new capacitor came in, I noticed it was a bit bigger than the old one, and had a mounting bolt on the bottom.  I thought I could cut that bolt off and make it fit in the housing, but after comparing side by side I realized I’d have to build a new housing if this thing worked. It’s just fine.

I used a couple wire nuts to connect the wires to the new upgraded capacitor, since crimping seemed so permanent.   I aired up the tank until it kicked off.  I did not notice any change in the sound of the motor, and it kicked on as usual with an empty tank.    Made it to 150psi and motor stopped.   Now to blow out some air and wait for the motors to sense lower pressure and kick on.  As my grandpa used to say “I’ll be jiggered”,  it worked. (He also handed down phrases like ‘Dryer than a fish turd in the hot sand’ and ‘Tighter than a cat’s butt’,  but I digress).  Being a realist, I expected the next one would fail–but it did not.  I retried and retried.  I tried it with all the lights on and my heater and garage fridge running, I tried it plugged into long extension cords and power strips.  I waited a couple days and tried again.  No failures yet, still working.   Could it be this simple?  Poor engineering from the factory?? Did they forget to carry the one when designing this thing?   More likely, trying to keep costs down and poor quality control.

I built a makeshift capacitor holder using an old angle bracket I had laying around.  I don’t have a cover for the new ‘plus sized’ capacitor, but plan on crimping the connectors and using some heat shrink wire wrap to help make it water resistant.   I didn’t modify any of the metal on the unit, I used the original bolt to hold the bracket.  Heck, I could put the old capacitor in, crimp it and take it back if I were so inclined (I’m not, and don’t think I would anyway–that would be admitting defeat).  If I had a 3d printer I might think about building a custom cover for it, but maybe that’s a future project.

So that’s it, hope this helps someone out there.  I did see this issue in more than one review.  It’s a fairly simple fix if you’re like me and really, really like how quiet this thing is.  BTW, electricity is dangerous, always use caution when dealing with capacitors.  They can shock and kill so always discharge before handling, don’t get sloppy, be safe.  Also, I’m an Amazon associate, so buying through an Amazon link supports me and this blog.

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