220v AC -> 12v DC

bankruatsteve · February 7, 2016

Seems like there should be some product that I can plug in to provide 12v DC for the purpose of running a DC air compressor. IE: versus running my car every time I want to fill a bicycle or motorcycle tire. I've "googled" rectifiers but don't see what I think I want. Maybe transformer first? Anyway.. it just seems like there should be a product out there that I can plug in to 220v and get a socket of 12v DC. Where?

Crossy · February 7, 2016

"Power supply" is what you are looking for.

BUT

An air compressor, particularly one intended to run from a vehicle battery, is an awkward load and will likely need a large and expensive power supply unit.

Better (and significantly cheaper) to get a motorcycle battery and a simple battery charger.

ThaiKneeTim · February 7, 2016

You need both a transformer and rectifier, the transformer drops the bolt then the rectifier converts it to DC. Off hand I don't know the load of a compressor is but you need to ensure that the power supply has a continuous rating that matches, or exceeds, the load current.

It isn't going to be cheap, or lightweight!

bankruatsteve · February 7, 2016

Aagh. Well, that was the solution I was hoping to avoid. (battery and charger) Not to suspect your input, but why should it be large and expensive to simply (or maybe that's the challenge?) convert to 12v DC. I wish I had the brain cells I must have destroyed.

Crossy · February 7, 2016

It is not necessarily either large nor expensive to convert 220V AC to 12V DC, I have a unit sat on my desk that does just that, it's about 3"x 1.5" x 1" including the plug pins. But since it is rated at a massive 1 Amp connecting that to your air compressor would send it (not the compressor) into orbit.

These little compressors are intended to run from a car battery which has essentially an infinite (i.e. no) current limit, they draw a very large starting current, maybe 30A or more, you will need a power supply that can provide that.

A 12V 30A power supply on AliExpress is about $25, probably about the same from NPE or similar in Thailand, but I cannot guarantee it will run your compressor.

Crossy · February 7, 2016

My 12V car battery charger does run my 12V tyre air pump.........

Can you hint at the ratings of the charger please?

lostinisaan · February 7, 2016

"Power supply" is what you are looking for.

BUT

An air compressor, particularly one intended to run from a vehicle battery, is an awkward load and will likely need a large and expensive power supply unit.

Better (and significantly cheaper) to get a motorcycle battery and a simple battery charger.

\

If it's only to fill up air in tires, why not a 12 volt compressor, plug it into your cigarette lighter and all is fine?

I've got a huge battery in my pick up, but it will also work with a smaller battery when you let the engine run.

lostinisaan · February 7, 2016

My 12V car battery charger does run my 12V tyre air pump.........

So does mine. And I can chose between bar and PSI. It even has a light.

ThaiKneeTim · February 7, 2016

You could always try a jump start with it's own built in compressor.

http://www.maplin.co.uk/p/compact-jump-starter-300a-150psi-compressor-n21kj

Not sure if they're available in Thailand though.

Crossy · February 7, 2016

To our members with battery chargers that will run their 12V compressors, please let us know the type and rating of the chargers.

I know my smart charger won't even think about turning on if it's not connected to a battery.

bankruatsteve · February 7, 2016

OK - the reason I started this is b/c I have a decent 12V compressor that plugs into the car but I just don't want to have to do that and start the car etc. I also have a 220v compressor (China I suppose) that works OK but has a pressure scale going from 0 to 200 psi at increments of 20 - so it's not easy to see where you want. It also has a connector that is a bitch to screw in/off. IE: it's a pain in the ass to use. But, it was the only one I could find that is 220v. Anybody know of 220v compressor that is good for this?

Dellboy218 · February 7, 2016

Lazada sell these 12V 30A supplies for B1450 which is more than enough for your compressor which looks like its 15 or 16A. Amorn also sell similar power supplies. Old fashioned, non smart battery chargers will power the compressor but dont rely too much on the spec they print on the front panels. I have a so called 20A charger but looking at the DC wires it would be pushed to supply 10A. Also be wary of the voltage they are pushing out. The output is not regulated or smoothed and the Voltage is likely to go higher than you (or your equipment) might like on low load.

Crossy · February 7, 2016

OK - the reason I started this is b/c I have a decent 12V compressor that plugs into the car but I just don't want to have to do that and start the car etc. I also have a 220v compressor (China I suppose) that works OK but has a pressure scale going from 0 to 200 psi at increments of 20 - so it's not easy to see where you want. It also has a connector that is a bitch to screw in/off. IE: it's a pain in the ass to use. But, it was the only one I could find that is 220v. Anybody know of 220v compressor that is good for this?

The DIY outlets all have compressors of various sizes along with the necessary accessories.

You should be able to replace the gauge / inflater of your existing 220v compressor with something more usable at a reasonable cost.

mike324 · February 8, 2016

OK - the reason I started this is b/c I have a decent 12V compressor that plugs into the car but I just don't want to have to do that and start the car etc. I also have a 220v compressor (China I suppose) that works OK but has a pressure scale going from 0 to 200 psi at increments of 20 - so it's not easy to see where you want. It also has a connector that is a bitch to screw in/off. IE: it's a pain in the ass to use. But, it was the only one I could find that is 220v. Anybody know of 220v compressor that is good for this?

I guess you are looking for something like this

http://www.lazada.co.th/gmy-12024wb-220v-to-12v-home-power-adapter-car-adapter-us-plug-black-2127465.html

bankruatsteve · February 8, 2016

OK - the reason I started this is b/c I have a decent 12V compressor that plugs into the car but I just don't want to have to do that and start the car etc. I also have a 220v compressor (China I suppose) that works OK but has a pressure scale going from 0 to 200 psi at increments of 20 - so it's not easy to see where you want. It also has a connector that is a bitch to screw in/off. IE: it's a pain in the ass to use. But, it was the only one I could find that is 220v. Anybody know of 220v compressor that is good for this?

I guess you are looking for something like this

http://www.lazada.co.th/gmy-12024wb-220v-to-12v-home-power-adapter-car-adapter-us-plug-black-2127465.html

YES! How did you find that? (rhetorical) I tried about 10 different searches in Lazada and never got that. Thanks!

No warranty and no specs but 375B, what the heck.

Edited February 8, 2016 by bankruatsteve

Crossy · February 8, 2016

OK - the reason I started this is b/c I have a decent 12V compressor that plugs into the car but I just don't want to have to do that and start the car etc. I also have a 220v compressor (China I suppose) that works OK but has a pressure scale going from 0 to 200 psi at increments of 20 - so it's not easy to see where you want. It also has a connector that is a bitch to screw in/off. IE: it's a pain in the ass to use. But, it was the only one I could find that is 220v. Anybody know of 220v compressor that is good for this?

I guess you are looking for something like this

http://www.lazada.co.th/gmy-12024wb-220v-to-12v-home-power-adapter-car-adapter-us-plug-black-2127465.html

YES! How did you find that? (rhetorical) I tried about 10 different searches in Lazada and never got that. Thanks!

But it's only 2A output.

bankruatsteve · February 8, 2016

Oh - didn't see that at first. Time to see if I can get a reading on my ammeter to see how much my 12v compressor draws. Or would it most certainly be in the 10-15a range?

Crossy · February 8, 2016

Oh - didn't see that at first. Time to see if I can get a reading on my ammeter to see how much my 12v compressor draws. Or would it most certainly be in the 10-15a range?

Suck it and see, but test it whilst on load pumping up a tyre.

You may score on a smaller power supply by starting it off load then connecting to the tyre.

When using it with the car do you have to start the engine to avoid running the battery down, or is it just force of habit?

Transam's 6A battery charger apparently runs his (I'm assuming a conventional charger rather than a 'smart' one) but we don't know anything about the actual running parameters.

If you don't already have a battery charger a decent 'dumb' one (say 6-10A) will likely do the job if you're not blowing up loads of tyres. If it smells hot, turn it off

Crossy · February 8, 2016

I'll bet the compressor uses a Mabuchi RS-540 motor (or something similar), cheap and mass produced.

Data sheet http://www.alphalanding.com/rc-track/rs_540rhsh.pdf

Probably the 9.6V variant, over-run on 12V to up the power a bit.

About 10A run current, nearer 60A when stalled (start surge).

bankruatsteve · February 8, 2016

Well, I guess I just need to re-visit the "Home" places for the 220v units. Previously, they just point me to the big gas engine compressors. Hopefully they will have something better than the one I got at Tesco.

Thanks for all the replies.

Oh - and yes I always start the car when using the 12v compressor (maybe from habit as it would draw down the battery if I didn't).

Edited February 8, 2016 by bankruatsteve

Crossy · February 8, 2016

We got a 2HP beast from MegaHome, about 4,500 Baht IIRC.

That was one of the smaller units they had but not the smallest. Great for inflating car and bike tyres, blowing up the inflatable pool and making a mess with the spray-gun.

Possibly a bit big for what you want, they do have rather smaller ones, but none as compact as the little 12V units.

I suppose it really depends upon how much and what sort of use it will get.

derekwyoung · February 8, 2016

Very few of either the compressors or the power supply are quoting AMPS, very very inportant , the compressors if they have it would be writen as LRA . Lock roter amps that will be the maximum that the compressor will draw when starting under load. most of the small power supplies shown are switching power supplies and do not like to exceed there quoted power output for even a tiny fraction of a second. and most of them are unsuitable for your purpose once blown are not so easy to repair. most compressors will run off of a 12 volt older type car battery charger not an electronic one. even without a motercycle battery across the output. hope this information helps. derek

mike324 · February 8, 2016

OK - the reason I started this is b/c I have a decent 12V compressor that plugs into the car but I just don't want to have to do that and start the car etc. I also have a 220v compressor (China I suppose) that works OK but has a pressure scale going from 0 to 200 psi at increments of 20 - so it's not easy to see where you want. It also has a connector that is a bitch to screw in/off. IE: it's a pain in the ass to use. But, it was the only one I could find that is 220v. Anybody know of 220v compressor that is good for this?

I guess you are looking for something like this

http://www.lazada.co.th/gmy-12024wb-220v-to-12v-home-power-adapter-car-adapter-us-plug-black-2127465.html

YES! How did you find that? (rhetorical) I tried about 10 different searches in Lazada and never got that. Thanks!

No warranty and no specs but 375B, what the heck.

I just search 220v to 12v. Sometimes simple searches will do the trick, those are the words most likely to appear on the items you are looking for. If you buy on lazada, a lot of the small stuff are actually shipped from China and may take more than a month, look for where the item is shipped from - if its from "abroad" a lot of times its China.

Guess its easier just to buy a 220v compressor. Here are some I found

http://www.lazada.co.th/tiger-ol-1204-minipancake-blue-772423.html

http://www.lazada.co.th/tools-pro-tiger-tgs-40-40-3900315.html

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