Hab electrics not working when switched to 'Cab' battery. (1 Viewer)

[Itsmcb]

Sorry if this is a bit long winded but I have totally confused myself. My 12v habitation area electrics have stopped working when I move the switch above the sink to the little 'cab' picture, they all work again when I move the switch to the 'rear' picture. I have replaced the relay under the bonnet which I assumed turns off the hab power when the engine is running (british van, 1996 Kontiki) but still have no power inside when the engine is off. Thanks to PappaJohn it now seems this may be the split charge relay and that the hab cut off is somewhere else. Anybody know exactly what I should be looking for?


Picture of mess under bonnet

Partial picture of power control unit in wardrobe

 

[Clivefog]

OK have you a leisure battery?

On mains hook up do the hab 12v electrics work?

The little rocker switch also used on caravans will switch between the two batteries, guessing hab battery dead or missing?

 

[Itsmcb]

OK have you a leisure battery?

On mains hook up do the hab 12v electrics work?

The little rocker switch also used on caravans will switch between the two batteries, guessing hab battery dead or missing?

I think you've misread my post. The electrics still work off the habitation battery. They don't work off the starter battery when the engine is turned off, which they should.

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[Ivory55]

Can not help you as your van is different to ours, our van just uses the hub battery not the starter for van electric.

 

[chatteris]

does it charge the hab battery when engine is running, could be blown fuse

 

[Clivefog]

OK got it well sort of. Mine does not work that way, engine off hab battery only for 12v, engine on I think only the fridge on 12v and split charge working.

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[Lenny HB]

Could just be the switch faulty I'm at a loss why anyone would want to run the hab electrics of the cab battery. A bit like turning the hab electrics off when the engine is running hangover from caravans.

 

[Potty]

Could just be the switch faulty I'm at a loss why anyone would want to run the hab electrics of the cab battery. A bit like turning the hab electrics off when the engine is running hangover from caravans.

When the hab battery is dead or nearly dead? We can do that until the cab battery has enough charge left to start the engine.

I understand that rather than this being a hangover from caravans, this is more to do with interference to cab electrics from non-suppressed habitation 12v equipment.

 

[68c]

Did it ever work off the cab battery? I ask as the switch may be to select battery charger to cab or hab, obviously will only charge on hook up.

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[Lenny HB]

I understand that rather than this being a hangover from caravans, this is more to do with interference to cab electrics from non-suppressed habitation 12v equipment.

Only done on Brit vans I've never had a van that does it.

 

[Itsmcb]

I think my main question is where do I find the relay which isolates the hab area when the engine is running?

 

[pappajohn]

Check the voltage to the rocker switch. If both hab and cab batteries are connected you will get a voltage off each. It may be the engine battery isn't connected to the switch.
If the hab cutoff relay has failed it will default to power on even with the engine running
When the engine starts the relay should be triggered and disconnects the hab side. Turn the engine off and it reconnects.

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[Itsmcb]

Did it ever work off the cab battery? I ask as the switch may be to select battery charger to cab or hab, obviously will only charge on hook up.

Actually that's a good question. I was pretty sure but not now certain. I know the little voltmeter next to the switch shows the state of charge of whichever battery the switch is switched to. Also I don't know if the onboard battery charger chargers the starter battery and don't have hook up at the storage to try it. AARRGG!

 

[pappajohn]

Did it ever work off the cab battery? I ask as the switch may be to select battery charger to cab or hab, obviously will only charge on hook up.

On my 99 Kontiki it did both....charge AND use whichever battery was selected.

 

[Itsmcb]

Check the voltage to the rocker switch. If both hab and cab batteries are connected you will get a voltage off each. It may be the engine battery isn't connected to the switch.
If the hab cutoff relay has failed it will default to power on even with the engine running
When the engine starts the relay should be triggered and disconnects the hab side. Turn the engine off and it reconnects.

Ahah. My brain is working again. There definitely used to be power to both sides of the switch and there is now no power to the Cab side. If the relay defaults to power on then there must be a fuse gone somewhere (or a broken wire). Does that sound correct.

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[pappajohn]

If the relay defaults to power on then

It's the hab isolation relay which defaults to on if it fails, not the hab charge/power relay.
As I said in the other thread, the isolation (engine running) relay was near the charger.
When you find it it's easy to override and have hab power with the engine on.... Remove either terminal 85 or 86 from the relay, whichever is earth.

 

[Itsmcb]

It's the hab isolation relay which defaults to on if it fails, not the hab charge/power relay.
As I said in the other thread, the isolation (engine running) relay was near the charger.
When you find it it's easy to override and have hab power with the engine on.... Remove either terminal 85 or 86 from the relay, whichever is earth.

Surely the split charge relay has no bearing on this though as the engine is off. There should be power to the switch even if the habitation isolation relay has failed due to it defaulting to on. Since I have no power there must be a break in the cable or hopefully a blown fuse? Unfortunately I have no idea where a fuse might be located?

 

[pappajohn]

Think we're both getting confused.
The hab isolation relay is connected directly to the engine battery... Or a suitable permenant live wire under the dash etc...and is triggered by the alternator running. but the relay could be anywhere in the van. It will most likely be fused at the point of connection, under dash or battery etc.
As I said, mine was next to the charger and leisure battery.
The fault could be burnt relay terminals on the secondary circuit, broken wire or blown fuse on the primary circuit.
Split charge is of no concern with the problem in hand.

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[Itsmcb]

More investigation tomorrow I think

 

[Ivory55]

What you need is a generator, always works every time. Haha

 

[Itsmcb]

Finally tracked down the fault today to a badly corroded push connection in the engine bay. Hallelujah

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