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Battery Charger fuse blowing.


Ventoux

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I have a Mobitronic charger under driver seat (Hymer 544 1990). A 10amp fuse adjacent to it keeps blowing when I drive the vehicle.

The only function that appears to fail when it blows is the DIN socket (not in use when driving), I use this for a Satellite receiver. If I replace the fuse after parking, the DIN socket works.

It started happening about 6 months ago and I can't remember any possible reasons.

Hope to be setting off again soon after wintering in UK.

Any help much appreciated before I resort to Garage labour charges.

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Sounds like a loose wire or something like a loose screw or a bit of metal ,shorting out the live too earth or negative,when moving due to vibration.Check as far as possible nothing is loose and floating around in the charger.if the fuse is blowing with nothing connected to the din power plug it can,t be anything else. :-S :-S :-S

 

Cheers.

 

martin

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Guest Tracker

Check the polarity of the din socket just in case it is reversed?

 

I don't know about din sockets but cigar lighter sockets generally have a 15 amp fuse - not that a sat nav wants 15 amps or anything like it - unless it also feeds something else - like extra lights maybe - internal or external?

 

If that fuse is also in the charging circuit as well as feeding the socket it may well need to be a 20 or 30 amps fuse to prevent blowing and carry the charge current - what does the handbook or wiring diagram tell you?

 

Is the wiring original or an add on by an enthusiastic amateur!

 

Does the fuse blow when the engine is switched on, started , or revved up?

 

Can't claim to be an expert - sorry!

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Logically, therefore, the circuit between the fuse and the Din socket is sound, otherwise the fuse would presumably blow when you are static, but something is drawing excess current via that circuit (or just the fuse) when you are driving.  Is the DIN socket isolated or live (blown fuses excepted) when the engine is running?  Is the fuse in the Mobitronic unit, or in a separate fuseboard alongside?  Is there a common feed to the live terminals of the fuses at the back of the fuseboard, and is it possible another fuse has blown, but that circuit is being back fed via the DIN socket circuit?  Say the fridge, or battery charger, circuits, that are normally live when the engine is running, but isolated when the engine is off?  Alternatively, is the wiring at the back of the DIN socket, or the socket itself, faulty?  I think some of these have a sprung positive terminal that is compressed by the plug.  Is it possible the sprung terminal is causing a short when unused, but when a plug is inserted and the terminal is compressed the wiring terminals are sufficiently separated to eliminate the short?
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Tracker - 2008-03-02 3:04 PM

 

Check the polarity of the din socket just in case it is reversed?

 

I don't know about din sockets but cigar lighter sockets generally have a 15 amp fuse - not that a sat nav wants 15 amps or anything like it - unless it also feeds something else - like extra lights maybe - internal or external?

 

If that fuse is also in the charging circuit as well as feeding the socket it may well need to be a 20 or 30 amps fuse to prevent blowing and carry the charge current - what does the handbook or wiring diagram tell you?

 

Is the wiring original or an add on by an enthusiastic amateur!

 

Does the fuse blow when the engine is switched on, started , or revved up?

 

Can't claim to be an expert - sorry!

 

Just checked fuse and it didnt blow on yesterdays 10 mile return journey.

 

Check the polarity of the din socket just in case it is reversed?

I'm confused already :-D I do not have any grasp of electrics.

 

unless it also feeds something else - like extra lights maybe - internal or external?

Confused again.

 

what does the handbook or wiring diagram tell you?

8-) Its lots of lines and numbers :D

 

The DIN socket looks like Hymer dashboard original but I'm not certain. Mobitronic charger put in by previous owner.

 

Does the fuse blow when the engine is switched on, started , or revved up?

I haven't ascertained that yet.

 

Thanks Tracker for responding.

 

Looks like its too complicated for a Forum with my lack of electrical knowledge :$

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Brian Kirby - 2008-03-02 6:14 PM

 

Logically, therefore, the circuit between the fuse and the Din socket is sound, otherwise the fuse would presumably blow when you are static, but something is drawing excess current via that circuit (or just the fuse) when you are driving.  Is the DIN socket isolated or live (blown fuses excepted) when the engine is running?  Is the fuse in the Mobitronic unit, or in a separate fuseboard alongside?  Is there a common feed to the live terminals of the fuses at the back of the fuseboard, and is it possible another fuse has blown, but that circuit is being back fed via the DIN socket circuit?  Say the fridge, or battery charger, circuits, that are normally live when the engine is running, but isolated when the engine is off?  Alternatively, is the wiring at the back of the DIN socket, or the socket itself, faulty?  I think some of these have a sprung positive terminal that is compressed by the plug.  Is it possible the sprung terminal is causing a short when unused, but when a plug is inserted and the terminal is compressed the wiring terminals are sufficiently separated to eliminate the short?

 

Is the DIN socket isolated or live (blown fuses excepted) when the engine is running?

Dont know.

 

Is the fuse in the Mobitronic unit, or in a separate fuseboard alongside?

Seperate fuseboard alongside under seat. Most slots empty except for a 10amp and 25amp fuse.

 

Is there a common feed to the live terminals of the fuses at the back of the fuseboard, and is it possible another fuse has blown, but that circuit is being back fed via the DIN socket circuit?

My brain is hurting :'(

 

Alternatively, is the wiring at the back of the DIN socket, or the socket itself, faulty?

Dont think so. I've pulled it out of the housing and all seems normal.

 

Looks like an electrical diagnosis is required Brian.

The fuse seems to blow intermittently.

My lack of knowledge is restricting the possibility of help via a Forum :-S

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Rather than resorting to local garage prices, which I should imagine is a relativly simple problem when checked out, I would contact a local auto electrian, and leave him to sort it, without having to take the van anywhere. Good luck chas
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My local auto electrician diagnosed a faulty Alternator last year. He kindly recommended a local garage to fit a new one ... it failed, 3 weeks into a 6 month trip around Europe. I had it repaired in Italy costing £120.

 

Thats just a little story. I will call him to have a look, he's only £20 per visit. Buy I'll get any work required done by a different garage this time.

 

Thanks Chas.

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Just as an aside might I mention that cheap blade fuses available at every £1 store are useless. Testing them gave results so far away from what they should be that I threw them away. 5 amps blew at 15 amps and 20 amps blew at 15 amps! Tip, buy good ones, you know it makes sense.

 

G

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