ARB compressor short

Hi all,

Last week I was out for a drive, and while airing back up my little 28l/m ARB compressor shorted out.

Attachment 82391

The 30A fuse blown and the leads were hot hot hot!

Today I checked alternator output at 2000rpm and was all good at 14.2V so no issues there. I chucked another 30A fuse in the compressor and instant blowout when hooked up to the battery.

Hmm, pulled the lead plug apart and lo-and-behold it's melted to the shizenhousen.

Attachment 82392

So cut the M/F plugs off and hard wired the leads back together.

Goes like a ripper again, no problems noted in my very quick run without load this afternoon.

So my question is, what could have caused the plugs to melt like this? Could it just be that every time I air up the little compressor is pumping for a good 20 minutes without stopping? It works hard the little thing and it's probably got 25-30 hours run time on it.

Was worried about the input voltage but all seems OK in this regard.

Could there be anything more sinister going on here?

G’day Plassy Mate!
Any chance that plug was tucked up hard under the compressor itself?
Possible radiant heat started issue instead of power related maybe?


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Originally Posted by MB

G’day Plassy Mate!
Any chance that plug was tucked up hard under the compressor itself?
Possible radiant heat started issue instead of power related maybe?


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Gday Scotchymaster! 99.9% sure it was fully out of the box mate.

I had pumped one tyre up and around half way into the second, so it was runnig for less than 10 minutes.

About 30 seconds before it stopped, the compressor sound changed from "under load" sound to "free pumping" sound, but I hadn't pulled the hose off. That was weird.

Do most compressors have a duty cycle? This little thing just runs while it has power no matter its temperature. Motor and air tank get very hot every time it's used.

Thinking this may have (over time) contributed to the softening/deformation of the lead plug and finally the plug shorted?

Shitty connection with those plugs after a while. Loose female connection not gripping well enough causes high resistance join which in turn creates heat. That's what happens with most connections.

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IMHO only... won't be the input voltage per se.

I would suggest that Compressor would be lucky to have a 20 minute on 40 minute off duty cycle so it would def get get super hot at 20 minute continuous.
The leads being copper (which obviously conducts heat) are probably the source of the heat that melted plug which is quite close to the compressor IE the leads will get bloody hot and melt the plug

To test that theory... run it for about 10 mins under load and check how hot the leads get.
If the leads get bloody hot then that is the issue, if they don't then it was most likely a poor connection at the plug.

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Originally Posted by matfew

Shitty connection with those plugs after a while. Loose female connection not gripping well enough causes high resistance join which in turn creates heat. That's what happens with most connections.

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Cheers Matt. This unit is about 12 years old so that may well have been the case.

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Originally Posted by the evil twin

IMHO only... won't be the input voltage per se.

I would suggest that Compressor would be lucky to have a 20 minute on 40 minute off duty cycle so it would def get get super hot at 20 minute continuous.
The leads being copper (which obviously conducts heat) are probably the source of the heat that melted plug which is quite close to the compressor IE the leads will get bloody hot and melt the plug

To test that theory... run it for about 10 mins under load and check how hot the leads get.
If the leads get bloody hot then that is the issue, if they don't then it was most likely a poor connection at the plug.

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The unit has always got really hot but never the cables. This time the cables were super hot!

Funny thing is, when I cut the plugs off today and stripped the insulation, the wires from the clamp ends were copper, the wires from the motor were silver colour. Does that mean anything to someone with elec knowledge (i.e. not me!)

As @matfew and @ET have mentioned its simply a plug interface issue with resistance resulting in heat thats melted the plastic. My old ARB compressor did the same on Fraser island pumping up 4 tyres from 10psi to 35 and the plug was like warm bread dough by the time I finished.

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Originally Posted by PeeBee

As @matfew and @ET have mentioned its simply a plug interface issue with resistance resulting in heat thats melted the plastic. My old ARB compressor did the same on Fraser island pumping up 4 tyres from 10psi to 35 and the plug was like warm bread dough by the time I finished.

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Makes you wonder why they would include this weakness into the design. Why on earth do the leads need to be removable via the plug?? Not once have I ever thought about unplugging them.

Almost always, heat in a connector is caused by poor connection resulting in heat, which then reduces the pressure on the connection resulting in more heat etc, etc.
Most of those 6mm quick-connect style connectors are rated at 20A max (that's the connector, not the cable) but it is very hard to find any definitive specs for even the good quality units - the cheapies would be anybody's guess.
Not really a good place for this type of connector. I would definitely get rid of it and either use something much higher rated, or just do a good soldered and well insulated joint.

Simple answer to the steel coloured wire. Its cheap, where copper is not. They may save a few cents per unit.

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Originally Posted by mudnut

Simple answer to the steel wire. Its cheap, where copper is not. They may save a few cents per unit.

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Is it plated wire for corrosion protection or steel? I have come across this stuff quite regularly and it can be a bit harder to solder, always thought it was plated copper?

Above post edited. Whatever it is, it is cheaper.

Yep all back to normal. 20 minute air up this afternoon. Wires were warm but not hot. Clips were hot but they always have been.

Tinned copper for corrosion purposes. I can say the only steel wire I have seen is fencing wire haha.

We use cable not wire.... Lol always something I got hammered into me as an apprentice. If you wanna play with wire go back to the farm haha.

It won't be steel as steel would crack and break in no time. It is just tinned copper. Not sure why it's harder to solar being tinned already it's half way to being soldered lol

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Quote:

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Originally Posted by matfew

Tinned copper for corrosion purposes. I can say the only steel wire I have seen is fencing wire haha.

We use cable not wire.... Lol always something I got hammered into me as an apprentice. If you wanna play with wire go back to the farm haha.

It won't be steel as steel would crack and break in no time. It is just tinned copper. Not sure why it's harder to solar being tinned already it's half way to being soldered lol

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Yeah, I just find its harder to get the heat into the CABLE when its tinned as you say - does not make sense unless the tin is acting like an insulator or maybe the flux thats in the solder isn't as effective as on straight copper - don't know.

If there is a dirty connection in the plug itself, it can cause heat.

Quote:

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Originally Posted by matfew

Tinned copper for corrosion purposes. I can say the only steel wire I have seen is fencing wire haha.

We use cable not wire.... Lol always something I got hammered into me as an apprentice. If you wanna play with wire go back to the farm haha.

It won't be steel as steel would crack and break in no time. It is just tinned copper. Not sure why it's harder to solar being tinned already it's half way to being soldered lol

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A lot of country high voltage is 3/12 steel wire. Very thin and highly strung. Often used as a SWER system. Absolute c**t to work with. Can't bend it beyond a certain angle as it just cracks..And working with it under tension it makes awfully scary noises .... When it lets go the whip effect slices steel like butter. We call it the widow maker conductor .

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