Battery switch

[Graham of Madrid]

Another silly question but I hate making mistakes by just guessing !

Does anyone have one of these ? Am I right is assuming I can turn it to the off position and this will remove any connection between cab and habitation batteries - useful when removing habitation battery ?

What is the third position for ?

Cheers ?

 

[Richard n Ann]

Depends how it's wired up.
3rd position is to remove the knob.

 

[Graham of Madrid]

Great thanks !
I wasn't considering doing an autopsy on the van just yet !! is there any non-invasive method I can use to find out what is does ?

It's good to be able to remove the knob, this must be a design feature. But why would I want to take it with me ?

I get easily confused, I keep losing things. Maybe I should leave the knob where it is.

 

[GeoffnDee]

It may be an isolator for the engine battery, see if you can start it with it in the off position , it could also be an isolator for the batteries to be used when in storage.

 

[Graham of Madrid]

Battery Master Switch for the habitation battery - I just read the manual ! It describes the switch as being a tool which you can remove.

Not sure how I'd check that though

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[autorouter]

I'm not a boater, but I think if the isolator is fitted to a boat, which is left in a marina or on a beach, it will stop kids playing with it if the knob is removable.

 

[autorouter]

this will remove any connection between cab and habitation batteries

Usually fitted on just the hab battery. A connection between the cab and hab batteries is the kind of emergency connection, used when your boat engine won't start out at sea.
An isolator on the cab battery should be used with caution, and never isolated while the engine is still running. I wouldn't fit one on a motorhome.

 

[Graham of Madrid]

Well mine is permanently on

 

[Whiskeymac]

Its a switch which isolates the habitation batteries, the only time you can physically remove the switch is when it is in the off position.

 

[pappajohn]

If you have solar you may have to disconnect the panel every time you switch the isolator back on.
Some controllers need to see battery voltage before solar voltage.

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[Graham of Madrid]

I'm assuming it isolates the hab battery from the vehicle battery and nothing else. I think the solar panel and habitation electrics will all function normally with the switch off - but I'm only assuming. The manual has no detail on this.

 

[autorouter]

Let's be clear about this. The hab battery should not be connected to the cab battery. Such a switch would only be for emergency use, as I stated previously. It has no place in a vehicle.

The split charge relay connects the hab battery to the cab battery when the engine is running, so that the alternator can charge both batteries. It disconnects them when the engine stops, so that habitation loads do not drain the cab battery and result in the engine unable to start.

 

[autorouter]

I'm assuming it isolates the hab battery from the vehicle battery and nothing else.

If you turn the switch off, so that the batteries are isolated, then you can check with a multimeter. Measure the hab and cab batteries at the battery terminals, they will no doubt be slightly different voltages. Measure the voltages at the two terminals of the switch. The voltages will correspond to the battery voltages if the switch does indeed isolate the two batteries

 

[Graham of Madrid]

Hey, Autorouter - you're beginning to make sense now !! All this talk about boats !!

Let's be clear about this, I didn't say the hab and cab batteries were permanently connected. Sorry you got that idea, sorry I wasn't clear enough. Yes they share some connection during alternator charging. I hope there is no connection that you refer to 'connect them together in an emergency scenario'. That would be unacceptable. Maybe on your boat !!

You've not taken the solar panel charging into your assumptions about the two batteries having different voltages. But thanks again.

You mention taking voltages at the switch - that involves taking things apart. If I had to that I'd probably be in a better situation than most to see what the switch is for. Thing is I don't want to take the things apart.

All I wanted was a better explanation about this switch than I had from my documentation. It ain't really that important.