Hobby battery switch (1 Viewer)

[timdownieuk]

This may sound like a dumb question, but what does this switch on the side of the driver's seat on my 09 Transit based Hobby Motorhome do?



I appreciate it's a battery main switch but turning it makes no apparent difference. Engine starts and everything seems to work in either position.

At the back of the switch there are three black wires, two connected to one terminal and one to the other. If I disconnect the wires from the switch I can confirm that the switch does open and close and that all the black wires appear to have continuity with earth.



The reason for my curiosity is that we've suffered a severely dead battery this winter and following its replacement, I thought it would be a good idea to maybe use the switch when the van is laid up to minimise discharge but it doesn't seem to isolate anything that I can tell so far.

Is it mis-wired or have I misunderstood its function?

Tim

 

[Jaws]

They usually isolate the hab battery(s)

 

[Jaws]

Oh, forgot.. The reason all wires appear to be connected even though off the switch is because you are getting a circuit through various things in the hab area

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[timdownieuk]

They usually isolate the hab battery(s)

Isolate the hab batteries from what? From all the 12v habitation circuits?

I suspect not in this case as the habitation battery is located on the other side of the van in the back and it's the engine battery under the drivers seat.

 

[Jaws]

All I can say is that is how both the Hobby and the Miller were wired

 

[andy63]

hi tim , im intrigued, sounds really odd and have a feeling you are going to have to trace a few wires.
cant understand how they all have earth continuity , and connected to both sides of the switch.. don't seem to serve any purpose.
look forward to hearing what you find.
ta andy

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[daveandsan]

I have a Hobby Siesta 650 and although my switch is in a different position to yours as Jaws has said it isolates the Hab battery from the 12v habitation area.

 

[tonyidle]

It also translates as Battery Main Switch.

 

[andy63]

there should be some measurable resistance on the wires to one side of the switch. I took continuity to mean direct to earth.

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[timdownieuk]

Bugger. I've refitted the seat now but I guess I can poke around with my multimeter from the front. More tests tomorrow.

Tim

 

[andy63]

hi tim, would have thought if its an isolation switch it would be on the live side, but you say you have continuity to earth on all the wires, so not sure. think you need to trace the wires, or give papajohn or jonandshell a pm. think they are both electricians and may have a answer.
ta andy

 

[vectian]

If its on the return side did the person fitting the new battery fit a new earth strap straight to the body from the battery

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[Jaws]

Just turn it off and see if anything in the had area works

 

[JeanLuc]

Are you sure that black wires mean it is on the -ve / earth side? I don't know whether this is common to all/most German-built vans, but Hymer use a wiring convention for 12V DC that is opposite to 230V AC. In mine, the battery connection cables are BLACK +ve, BROWN -ve. Blue is also used for +ve on some 12V DC cable runs to sockets, lights etc.
I may be at risk of misleading you but suggest you need to check cable colour / polarity with a multimeter if you have not already done so.

 

[timdownieuk]

Well, as far as I can make out, the switch does feck all. ;-) It might have some effect during charging but everything in the van works with the switch in either position.

I tried to measure the resistance between the terminals with the switch open today but my multimeter just swings full deflection showing no significant resistance. I'm puzzled.

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[andy63]

if im getting this right you seem to have an isolator switch that has no power to it and connected to earth (body of vehicle) on both sides . don't make sense to me and the only suggestion was as I said earlier just trace the wires to wherever they go..
on the plus side if you find it is not doing anything there is nothing to stop you rewiring it as a start batt isolator switch which is what you wanted in first place. (provided the switch is rated for that sort of current)
ta andy