I repair a dumpster diver portable 12 volt car air compressor

[@hughgaynor4320]

In this disposable society so much gets thrown away for want of a few minor parts. The last 12v compressor I had to throw away had a stripped nylon gear. I replaced it with a 240v cheap compressor. Another good video Rob.

[@Xynudu]

Thanks Hugh. It gives viewers an idea of things to look for. Still works with a few internal organs missing ;) Cheers Rob

[@ronsites2694]

I love it when you fix someone else's junk. Lots of good stuff to be had for free. Thanks for the video.

[@fun_ghoul]

As someone whose supper was cooked in a garbage picked Le Creuset pot, congratulations on your find.

[@dankolar6066]

That was fun. At least the defect wasn't a shattered irreplaceable molded plastic part. Thank you for sharing.

[@SeanBZA]

Got almost the same GE battery charger, just from around 1950. Replaced the original selenium rectifier and put in a little bit extra to have charge limiting and reverse polarity battery protection. Nice job on fixing that for free, can't beat free plus an hour of your time to make it just as good as new, and 100 times as good as the modern plastic junk.

[@WallStreet749]

I would of replaced the thermal switch Those portables Air units run Hot not having it connected you could burn that nice motor up. That unit sells for 140.00 . Id paint it and bring it back to a new condition again. Nice find.

[@wayneo7307]

Good Job Rob ! Enjoyed Watching . I like watching the Deduction Work .

[@metalshopwithtroy5755]

Great video Rob have one the same will now have a crack

[@redapproves1330]

Great find and even greater fix! Thank you for another inspirational video sir!

[@ChrisB257]

Wish I managed to find the stuff you do Rob - excellent and satisfying result. :)

[@Xynudu]

Thanks Chris. This one belong to the Bro Inlaw. He's in a class of his own on scrounging this stuff. Never a dull moment.

[@markdurant9576]

Good repair Rob, keep them coming.

[@johanandersson9287]

Well done again, Rob - another blow for Dumpster Diver freedom! 2 cents: As the DC motor is fairly lo rev and acting directly to the piston, you could have quite a bit of current hogging by this beast - especially when the pressure's topping out and the revs go down. The rating of the auto fuse should be a giveaway to its max current, but remember that momentary current could well be over 2 x nominal. You might also find that the 16 A switch welds itself open on shutoff. Those relays can take above 30A, so you could reinstall that to protect the switch. Then everything will probably run just fine. Cheers, DIYSwede

[@Xynudu]

Hi Johan, The winding on the armature is hellishly heavy gauge. So it's an amperage hog. But the relay only had your normal 10/15 amp connector tabs on it for trigger and feed wires. Weird. Will see how it goes and if the switch fails I will put back the relay. Cheers Rob

[@sonofedmund5004]

I just got.a Bon-Aire 12v tyre air compressor from a flea market. It was in it's bag with all the accessories and manual. The guy said it wasn't working got it for £2. All that was wrong was the 15 amp fuse had popped. This was #1 fix in the manual. Put a new one in, bingo!

[@Xynudu]

Now that's a bargain. Nice to be a winner at times. Gotta love those flea markets. Cheers Rob

[@rayfalcone6897]

Well Rob, you did it again.......always amazed with your videos, have a great day.......again I enjoyed your video, with a nice cup of coffee at breakfast....take care till next time...

[@allengentz7572]

Great stuff Rob love restorations,Thanks be to your brother inlaw we could see many more.

[@Xynudu]

It's quite possible.

[@swarfrat311]

Thanks for the video, Rob. You could have yourself a nifty little business by fixing up junk and selling it at a yard sale. Have a good one! Dave

[@ewanvisser7913]

That's a 160L/min air pump and has a max amp rating of 45amp. If it's under load it's going to burnout that switch. Well done getting it back to life 😁

[@MiniLuv-1984]

Nice one! Perhaps you can put a thermostat (normally on) against the body of the motor and run power through that, or preferably though the relay? These things can take 10 minutes or more to pump up a tyre from flat, so I get bored and move away to do something else while it is running - in which time it may just overheat and blow a winding.

[@ActiveAtom]

Hi Rob, this is a great week to be had, thank you for saving one mans disregarded item from certain death, Lance & Patrick.

[@Paulman50]

I was thinking a minimum of 10 amps. Hope your weather stays good for a month or two so we can have nice holiday over there.

[@EverettsWorkshop]

I love watching your stuff. You're a dumpster diver after my own heart. It only becomes a problem when one is a packrat as well, lol . . .

[@michaelsimpson9779]

Lottsa good stuff in skip bins....👍

[@Xynudu]

Yes indeed!

[@rude252]

Nice one Rob! I have a similar compressor and they come in handy. Have even topped up tractor tyres. From memory max current draw is around 45a.

[@Xynudu]

Hell. I might have to put that relay back. Cheers Rob

[@ae93gti]

@@Xynudu just came across your video, I was wondering on removing the relay 🙂

[@ae93gti]

Never mind, came across your next/other video, thanks!

[@oxdudepoege]

Thank you so much for this video. Now I know how to trim off some unnecessary weight on the same compressor I bought brand new to hard mount it into my Jimny. 👍👍👍

[@munecito]

Be careful pulling the relay out. These things actually draw about 40A not 13A. The switch will melt soon enough.

[@dalegriggs5392]

My wife is quite embarrassed at my dumpster diving but after fifty years she’s come to accept it. Glad you left off the motor cover. I was thinking as you removed it I wouldn’t put it back on. Seems to me it would hold in heat and possibly damage that permanent magnet motor. Tell me Rob, what truck did you use to get those long bolts back I properly? They are notoriously difficult to align as the magnets grab them preventing proper insertion. That particular compressor looks like a pretty heavy duty unit. Most on the market today are super chinsey and not worth carrying out of the store. They barely pump up a single tire before they seize up. I have a neat little 12 volt compressor I salvaged from a travel trailer water system that used compressed air to activate the water system. I’ve had and used it for over forty years and it just keeps pumping air. The thing is even oil lubed just like a large unit. It will pump up to 100 psi. On a quarter inch line it takes awhile but the little thing has got some punch to it. CFM isn’t anything to crow about but it’s very useful for a number of applications.

[@Xynudu]

Hi Dale, Yes, the cover was just decoration and a heat trap. These units don't have a thermal cut out for temperature (only short circuit current draw) or a fan of any sort, or even cooling fins, so heat build up will be severe. With the cover off you can now at least feel the motor casing temperature. Cheers Rob

[@garyhardman8369]

Hi Rob. Good video as always. Just one thing. The relay is there for a purpose, you'll probably find that the switch is only rated 15A AC. When you switch off a DC motor, it generates a back EMF which can be many times higher than the DC supply voltage. Even though the switch was not getting hot, it will probably be arcing badly inside. I'm guessing that it will not last very long.

[@Xynudu]

Hi Gary, My clamp meter showed 24 amps draw which was way higher than the switch, yet the switch was cool. Also the relay only has standard 10/15 amp connectors on it. So I was thinking the meter must be wrong (ripple). The relay and overload are both unmarked, so no way of knowing what they are rated at. I will do some more testing with a line meter. I think you are correct and the relay should go back. At least we know it works ;) Cheers Rob

[@munecito]

I'm coming very late to the party. I just put one of them apart yesterday. The relay is marked 60a sh-4141-a. When I hook it to my portable battery box it draws 38 amps under load.

[@HealthSupercharger]

I have a 50 dollar 3 year old one and I was thinking of upgrading the cord because the stock is probably a 18 gauge and is for a cigarette lighter and short only 12ft long barely enough to go to back of my truck tire. I was thinking of using an extension cord 25 foot long and add clips to it so I can directly hook it up to my battery. Do you think that a 16 gauge extension cord is a good idea? it has a 15 amp fuse so probably draws 10 to 13 amps.

[@Xynudu]

I think it's a bad idea to reduce the wire diameter and increase the length together. It will have a negative effect on current carrying capacity. It may not affect performance enough to be an issue though. The cord may get warm from overload. Try it and see. It can't hurt the motor. Always run these compressors with the truck engine running as they pump faster with the extra input from the alternator. Cheers Rob

[@IIIPronGIII]

You should refit the relay, these compressors draw around 45 amps. The purpose of the relay is to take the load, same thing if you were wiring up a set of spot lights. The switch isn't going to last long.

[@Xynudu]

Once I realised the current draw was in deed 25 amps +, I immediately fitted a relay. The original one was stuffed (see next video).

[@pierresgarage2687]

Yah...!!! Dumpsters are still a great source for curious and almost good objects, just need to faster than the local scrappers...!!! lol

[@Xynudu]

The name says it all. He He. Last in is lousey!

[@scroungasworkshop4663]

Hey Rob, FYI, Superheap have a suspiciously similar compressor on sale in their latest catalogue. The regular price is not cheap either at $249. Good work mate, cheers Stuart 🇦🇺

[@Xynudu]

Hi Stuart, Thanks for that. I guess these are a generic unit sold by lots of car accessory outlets. For that sort of money they should be better made. Wouldn't cost any where near that wholesale from China. Cheers Rob

[@scroungasworkshop4663]

xynudu. I completely agree Rob but it’s all about profit. I have talked to 2 people that supplied to a huge Aussie hardware chain and the way they are treated is disgusting. Small suppliers are locked in to exclusive contracts which are renewed yearly and things are ok for a year or two then the big chain and starts telling the suppliers what the chain will pay them. As the suppliers have stopped supplying to other customers the chain has them by the balls so the little guys have to find ways to cut costs or go broke. We have started going to where the tradies go ( no not that one) and usually find a better range or better quality as tradies won’t put up with rubbish and generally not to much price difference. How can the big chain and it’s off shoots sell things at 50% off during a sale? Because the mark up is so high to start with and we all know they don’t make a loss no matter how much it’s discounted. Sometimes, just for shits and giggles, I will compare the prices here with the same tools in the US and it makes you cry. We are so ripped off here. Anyway I’ll get off my soapbox now. Also I recently picked up a 1 1/2 x 3 ton ratcheting Atlas/ Dake US made arbor press to restore but I am missing the handle ( technically called the counter weight ) and the ratcheting pawl so if you or anyone else reading this comes across one I would be very interested in purchasing. You can contact me by replying to this thread. I hope you don’t mind me high jacking your site. I will happily remove it if prefered. Thanks heaps, Stuart 🇦🇺

[@Xynudu]

Hi Stuart, That's OK. It's not spamming. From what I know the big stores have 100% mark up on most stuff. They charge for shelf position etc. Pretty ruthless. Cheers Rob

[@scroungasworkshop4663]

xynudu. Cheers for that Rob. I want to get my own channel up and running but I have to many projects to finish first. I have a collection of gear waiting for restoration and that’s what I would mainly be focusing on. If my channel is half as good as yours I’ll be happy. Thanks mate, Stu. 🇦🇺

[@Xynudu]

Hi Stuart, Do it. I always have a backlog of videos/ideas to do and if I do have a quiet spell it makes for a good break. Doing YT has a life of it's own and can get out of hand ;) I never intended to have a channel, but as they say, shit happens in life. Cheers Rob

[@Xynudu]

The thermal overload switch is only current draw related. It basically acts like a fuse in case of an internal short circuit. It won't protect a motor from being overheated due to a too long run time. So leaving the square tin motor cover off is a good thing for cooling. The motors on these compressors are pretty crude as they generally don't have any form of external or internal fan cooling to dissipate heat. Could definitely be designed a lot better. After researching the current draw on this sized unit it appears the clamp meter reading of 24 amps was correct, so I will put the relay back in to protect the on/off switch. Cheers Rob

[@mattr1132]

they definitely pull a shed load of current. I’ve seen some twin piston models pull 40A! If you google 12v compressor comparison one of the magazines did a run through and give some tested specs.

[@AlexandreSchmidtBR]

Hey! Nice video! In your experience, would you see any issue in using this compressor sideways? I have a very similar one and would like to mount it horizontally because of the limited space I have. Do you think it could impact the cylinder somehow? Thanks!

[@Xynudu]

Should be quite OK in any position as it's oil less (runs totally on sealed bearings). Just allow space for air cooling. Cheers Rob

[@MattSeals]

Thanks! It is an terrific video!

[@nathanielpeterson5380]

You didn't show how you put the cylinder on.

[@AdilKhan-sh9fv]

Hi, I have a similar compressor but not any of the equipment . How can I check if the issue is with the wire or the compressor before dismantling it all? Thanks.

[@Xynudu]

Hi Adil, check the leads for continuity - put a multimeter across both leads and with the switch in the on position, do a resistance/OHMS check. I expect it will show open circuit and you will have to pull the unit apart to check the relay. Cheers Rob

[@AdilKhan-sh9fv]

@@Xynudu Thanks, Rob. I don't have experience with electricals, so pardon the ignorance. I'll need to Google those terms but from what I found so far, I would need to open up the compressor, connect the relay to the car battery and then check the relay via multimeter device because you suspect that the relay might need to be changed? kzbin.info/www/bejne/n6PIaKmvedaYosk

[@Xynudu]

Hi Adil, yes, that's probably what will be required. The relay was bad on the one I fixed, so it's probably a weak point with them. If you by pass the relay and the unit runs, then that shows the relay is bad. There is also a thermal cutout from memory, so by pass that as well. I expect it will be one of those that is the issue. Cheers Rob

[@AdilKhan-sh9fv]

@@Xynudu Hi Rob, I bought this multimeter imgur.com/gallery/K2y0rnH . The screen keeps saying OL when I switch to that wifi sign / arrow sign setting with compressor on on/off (unplugged to any power source though). Would this mean Open Circuit and I need to dismantle ? I tested the multimeter on a AAA battery and it showed 1.5 V, so I know the device is functional. I hope you don't mind the basic questions I'm asking here. Thanks.

[@Xynudu]

Hi Adil, yes that would indicate open circuit. When you touch the probes together it should show a number, which is the OHM/resistance reading. If you put it across the compressor leads and it shows OL it indicates there is a break or non functioning switch/relay in the unit and the tiny current flow sent from one probe to the other has been fully interrupted. I'm only a basic electronics user, but am happy to pass on what little I know. Cheers Rob

[@iTeerRex]

I also cut out the giblets out of machines if I go in there lol, or replace it with a good one if it has to be there.

[@glennfelpel9785]

That was interesting indeed. What do you think the relay was it there for in the first place? Do you suppose the put a relay in so they could use a lighter switch? I don't understand that either. Nice video Rob, thanks

[@Xynudu]

Hi Glenn, It looks like it was there to take load off the on/off switch. My clamp meter may have been reading correctly at 24 amps, so I will check with a line meter and if that is correct I will put back the relay. Bit of rework may be required ;) Still, we know it works. Cheers Rob

[@glennfelpel9785]

Right I understand. But still it is nice to have a switch. Cheapie me would likely just delete it too and let the alligator clamps to the job.:-)

[@Xynudu]

You sound like a farmer ;)

[@glennfelpel9785]

A really cheap one at that too Robbie :-)

[@Xynudu]

Ha Ha. The way to go.

[@shawnmrfixitlee6478]

great fix man , What does it draw under load ?

[@Xynudu]

I'm not sure Shawn. My clamp meter couldn't read it correctly due to current ripple/transients from the armature. Seems to be less than 16 amps as that's all the switch is good for. Cheers Rob

[@shawnmrfixitlee6478]

@@Xynudu Well that's not bad , Good save man !!.. Looks like a heavy duty one to ..

[@Xynudu]

Hi again Shawn, I'm now thinking the relay should be there as these things are a current hog, so I will put a line meter on the feed and see what it shows. Maybe the clamp meter was reading correct at 24 amps. If it was, then the relay has to go back. Looking on the web it appears that may be the case. A bit of rework may be required. Still it's a goer :) Cheers Rob

[@shawnmrfixitlee6478]

@@Xynudu it is a heavy duty pump , maybe needing the relay inline .. I still say AWESOME FIX !!

[@Xynudu]

He He, thanks Shawn.

[@RickRose]

Well don Rob.

[@TestSpaceMonkey]

Not really critical since it works now, but if you were still curious about the current draw, you could build a quick current shunt resistor our of some spare wire (kzbin.info/www/bejne/oGXYaZmiaJamnbM) and look at the wave form on one of those cheap banggood oscilloscopes.

Xynudu Recycling centre.