Blowing fuse??? (1 Viewer)

Monty1083

Free Member
Jul 29, 2013
31
13
Gloucestershire
Funster No
27,212
MH
Coachbuilt
Exp
I'm a Newbie
I have a portable air compressor, just a small thing for blowing up tyres, air beds etc. which operates from the cab 12v cigar lighter socket.

I bought a 5m 12v extension cable so that the compressor would reach the rear tyres on the M/H.


The compressor seems to work ok when it is plugged into the cab socket but when connected using the extension lead the cigar lighter 10 amp fuse blows.


I had also intended to use the extension lead to connect a 12v pump to fill the water tank from an Aquaroll but not sure if this is a good idea.


Any suggestions as to why the extension lead should cause this to happen?
 

pappajohn

LIFE MEMBER
Aug 26, 2007
43,204
48,797
Dark side of the moon
Funster No
172
Exp
Since 2005
the extension lead is far too long.

as the length increases the volts drop and the amps rise so you are overloading the 10amp fuse.

i had the same problem with my mini compressor to the point the compressor could barely turn under load.....but it was extended by 8mtrs and trying to pump 80psi.

i then went the other route and extended the air hose but had the problem of air compressing in the hose on each piston stroke but as there wasnt enough volume on each piston stroke to push air into the tyre so it merely expanded in the hose on the downward (uncompressed) piston stroke.

i finally solved the problem using a large motorcycle battery to power the compressor in its normal configuration....3mtr cable and 1mtr hose.
 
Last edited:

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
Faulty extension lead.

Some subtle fault with the connectors ?

Subscribers  do not see these advertisements

 
OP
OP
Monty1083

Monty1083

Free Member
Jul 29, 2013
31
13
Gloucestershire
Funster No
27,212
MH
Coachbuilt
Exp
I'm a Newbie
the extension lead is far too long.

as the length increases the volts drop and the amps rise so you are overloading the 10amp fuse.

i had the same problem with my mini compressor to the point the compressor could barely turn under load.....but it was extended by 8mtrs and trying to pump 80psi.

i then went the other route and extended the air hose but had the problem of air compressing in the hose on each piston stroke but as there wasnt enough volume on each piston stroke to push air into the tyre so it merely expanded in the hose on the downward (uncompressed) piston stroke.

i finally solved the problem using a large motorcycle battery to power the compressor in its normal configuration....3mtr cable and 1mtr hose.

Sounds feasible.... Do you think it will be the same then with the water pump idea? (Although my neighbour uses this method without a problem).
Other than carrying a motorcycle battery is there any way around it other than carrying a foot pump!
 

pappajohn

LIFE MEMBER
Aug 26, 2007
43,204
48,797
Dark side of the moon
Funster No
172
Exp
Since 2005
I dont think a water pump would be a real problem....not as heavy a load but maybe a little slower than it could be.

you could try heavy wires to prevent volt drop....maybe 6 or 10mm

once i abandoned the extension lead and hose idea's and used a second battery the compressor would easily pump 80psi into my tyres.

i have since modded the compressor to fit on a 24ltr air tank which has an auto cutout switch set at 115psi....no problem getting to 115psi and capable of a higher pressure if needed.

the compressor wiring is 'as bought' but only 300mm long from compressor to switch and a further 600mm from switch to battery.....doesnt even get warm
 

happypre65

Free Member
Nov 12, 2010
137
53
Funster No
14,423
blowing fuse

::bigsmile:Hi,Same problem for me, so i extended the cable by using two connectors and some more cable and it has now been working for three years,done the same for my daughter and no problem,as the saying goes ,dont make a mountain out of a mole hill,regards H.

Subscribers  do not see these advertisements

 
Apr 22, 2013
911
660
Cotswolds
Funster No
25,654
MH
Bailey Approach 625
Exp
Since 2011
I'm with Brian on this one.
A fault (short) in or caused by the extension lead.

Does the fuse blow with just the extension lead plugged in the socket?
or only after the compression is plugged in the lead.
This may indicate which end of the lead is causing the problem.

Gordon
 

Scout

LIFE MEMBER
Apr 4, 2009
3,955
119,798
South Yorkshire
Funster No
6,145
MH
chic c line
Exp
12 years motorhoming, a lifetime of living
why not just put your CAR near the m/h wheel where you need to pump up and plug into it,:thumb:
 

estcres

Free Member
Oct 9, 2007
1,300
767
Sunny Bournemouth
Funster No
582
MH
coachbuilt
Exp
since 2005
This is typical, using a machine to do a job that can be done manually quite easily.

Get a footpump and get some exercise at the same time,

I've got a footpump for the vehicle tyres and a hand pump for my bicycle tyres, never had a fuse blow

Subscribers  do not see these advertisements

 

SuperMike

Free Member
Apr 28, 2010
2,477
7,593
St Albans
Funster No
11,285
MH
Winnebago Sightseer
Exp
11yrs, but many years a tugger.
the extension lead is far too long.

as the length increases the volts drop and the amps rise so you are overloading the 10amp fuse.

i had the same problem with my mini compressor to the point the compressor could barely turn under load.....but it was extended by 8mtrs and trying to pump 80psi.

Although it is possible that the extension lead is faulty, have you checked it with another device ?

If the extension lead is ok, then PPJ is spot on with this analysis. If you took a cross section of these extension leads you would find that the amount of copper in them is minimal and they are basically unfit for purpose. :Doh:

Bloody hell, I'm agreeing with himself, everbody watch out for the pigs. :ROFLMAO:
 
Last edited:

JJ

Mágica
May 1, 2008
19,228
47,725
Quinta Majay, Pinheiro Bordalo, Portugal
Funster No
2,459
MH
Burstner Privilege T
Exp
over 50 years
Resistance.

That's the problem.

Cheapo extension cable = increased resistance = more current needed = blown fuse.

Solution. Fatter (or more conductive) extension cable wire allowing the little electron thingies to move around easier.

(Or use a big nail for a fuse)

JJ :Cool:

PS. Please note. The nail bit was a JOKE.

 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
Resistance.

That's the problem.

Resistance is useless.
Resistance is useless.
Resistance is useless.
Resistance is useless.
Resistance is useless.
Resistance is useless.
Resistance is useless.
Resistance is useless.

Subscribers  do not see these advertisements

 

rainbow chasers

Free Member
Oct 30, 2009
3,680
1,725
Mid Cornwall
Funster No
9,132
MH
Various
Exp
9
Resistance.

That's the problem.

Cheapo extension cable = increased resistance = more current needed = blown fuse.

Solution. Fatter (or more conductive) extension cable wire allowing the little electron thingies to move around easier.

(Or use a big nail for a fuse)

JJ :Cool:

PS. Please note. The nail bit was a JOKE.

:ROFLMAO::ROFLMAO:......I was hoping it was! Good explanation though!


Best way to demonstrate this is laymans terms is with a hose.

Turn on you tap to just a trickle. Wait until the water comes out of the hose at it's trickle rate.

Now lift the hose into the air. The water supply will stop, as it needs more pressure to reach the end. To do this, you need to open the tap a little more to maintain that trickle and overcome the resistance.

This is similar to electricity - you need to 'open the tap' a little more. To do this, you need a bigger fuse (opening tap) and a suitable cable to carry that higher 'pressure' (amps).
 
Jan 18, 2010
538
138
Airdrie Scotland
Funster No
9,996
Exp
6 years and 20 years as a tugger
the extension lead is far too long.

as the length increases the volts drop and the amps rise so you are overloading the 10amp fuse.

i had the same problem with my mini compressor to the point the compressor could barely turn under load.....but it was extended by 8mtrs and trying to pump 80psi.

i then went the other route and extended the air hose but had the problem of air compressing in the hose on each piston stroke but as there wasnt enough volume on each piston stroke to push air into the tyre so it merely expanded in the hose on the downward (uncompressed) piston stroke.

i finally solved the problem using a large motorcycle battery to power the compressor in its normal configuration....3mtr cable and 1mtr hose.
I did the very same thing added an extension cable to reach the back wheels and have not had any problems with fuses or drop in preasure

Bill
 

jonandshell

Free Member
Dec 12, 2010
5,476
8,299
Norfolk
Funster No
14,648
MH
Not got one!
Exp
Since 2006
How can more resistance make more current flow?

I'd say the extension lead has a dead short inside.

Subscribers  do not see these advertisements

 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
How can more resistance make more current flow?

A simple DC brushed motor is virtually a short circuit at low revs. It's back EMF rises with revs and the current drops as does the torque. This is why DC motors are excellent for vehicles, max power for take off.

The compressor will spin up to revs faster than the fuse will blow.

Now add a little resistance. The motor can't spin up quickly and can't reach full revs so will as PJ said, draw more current.

10A is not much of a fuse anyway, some of our sockets are labelled 16A and I think the German ones are on 15A fuses.

Ill admit PJ 1 : Hilldweller 0 on the first posts.
 

jonandshell

Free Member
Dec 12, 2010
5,476
8,299
Norfolk
Funster No
14,648
MH
Not got one!
Exp
Since 2006
Even a 16kW motor shows 5 ohms with a multimeter when static. I do buy your explaination of increasing resistance with motor speed but in this case I reckon its a dodgy lead!
We would have plenty of problems if we only rated fuses at motor running amperages rather than stall currents!::bigsmile:

Subscribers  do not see these advertisements

 

hilldweller

LIFE MEMBER
Dec 5, 2008
605
36,108
Macclesfield
Funster No
5,089
MH
Zilch Mk1
Exp
From Aug 2007
but in this case I reckon its a dodgy lead!
We would have plenty of problems if we only rated fuses at motor running amperages rather than stall currents!::bigsmile:

The lead was my first guess. Those cigarette sockets are as crap as you can get and call them connectors.

In this case the fuse isn't rated for the motor, we don't have any clues on the motor load so as usual just guessing, intelligently of course.

I have a cheapo compressor used with a cheapo extension but it's usually plugged into the DIN sockets. It works.
 

Join us or log in to post a reply.

To join in you must be a member of MotorhomeFun

Join MotorhomeFun

Join us, it quick and easy!

Log in

Already a member? Log in here.

Latest journal entries

Funsters who are viewing this thread

Back
Top