Run a 12v portable air compressor off a battery charger?

Submitted: Saturday, Jan 17, 2009 at 12:37

ThreadID: 65204 Views:9259 Replies:5 FollowUps:4

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Sigmund

One for the tech savvy ...

The charger is a conventional car battery unit, the compressor an ebay special with specs:

Maximum Voltage: 13.8 volt
Maximum Amperage Draw: 30 A

Feasible?

For inflating tyres where there's 240v but not a decent 12v (ie. shed that houses the motorbike).

TIA.

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Reply By: autosparky - Saturday, Jan 17, 2009 at 12:43

Saturday, Jan 17, 2009 at 12:43

in theory it can be done ,but the charger is not really designed to do it . and will die prematurely. buy a cheap compressor(240v) from some of these auto accessory places .would be a better idea for me

AnswerID: 344763

Reply By: Member - Ed. C. (QLD) - Saturday, Jan 17, 2009 at 12:47

Saturday, Jan 17, 2009 at 12:47

Does the 'bike have a battery?

If so, I'd be connecting the charger to said battery, and running the compressor off that....

Confucius say.....
"He who lie underneath automobile with tool in hand,
....Not necessarily mechanic!!"

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AnswerID: 344764

Reply By: Geoff (Newcastle, NSW) - Saturday, Jan 17, 2009 at 13:24

Saturday, Jan 17, 2009 at 13:24

Some chargers require a back feed from the battery of about 9 volts to kick start the switch mode power supply.

You certainly won't have this.

The other thing is there will be a sizeable starting current from the compressor that may trip the battery chargers short circuit protection.

The other thing is I assume you are actually talking about a battery charger of greater than 30 Amps output?

Geoff

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AnswerID: 344767

Reply By: Sigmund - Saturday, Jan 17, 2009 at 13:26

Saturday, Jan 17, 2009 at 13:26

Thanks autosparky.

I've got a spare charger so maybe for the occasional emergency ... ?

Ed C: yes it does, but it's about the size of 2 cigarette packs and v. expensive to replace :-{

Maybe if the bike engine were running ... ?

AnswerID: 344768

Follow Up By: Sigmund - Saturday, Jan 17, 2009 at 13:30

Saturday, Jan 17, 2009 at 13:30

Thanks Geoff.

Think we were typing at the same time.

Max draw of the compressor is 30 amps. Dunno what the min nec is.

I have a multi-meter but am an ignoramus. Can it be used to check the charger output amps?

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Reply By: oldtrack123 - Saturday, Jan 17, 2009 at 14:45

Saturday, Jan 17, 2009 at 14:45

Hi Sigmund
If the charger is one of the small 4amp types it has no hope of running the compressor. DOES charger HAVE ANY INFORMATION ON IT RE CAPACITY??
It would be a big charger to start/ run the compressor. The 30amp draw would probably be when it's at max rated pressure capabilty.BUT the start up current can be very high especially if starting against tyre pressure, I doubt if its practical to even try unless you have a reasonable size battery connected to supply startup current. NOTE battery chargers RECTIFIED AC itis not smooth dc as from a batteryas well as the voltage generally being aroun d 17+v open circuit . The open circuit voltge would not harm a transformer type charger , but could cause damage to any with electronic components Generally chargers should always be used in conjunction battery when using 12v gear, the battery smooths the output & reduces the voltage to that based on the batter' state of charge.

AnswerID: 344784