Use of vehicle battery

Can anyone confirm the leisure side of the van will never drain the vehicle battery?

I have read the extract below from the manual for my 2017 AS Warwick Duo fitted with the EC480 digital control panel and an EC500 thingy :-)
The description of the "battery select" button says that "by default, the leisure battery is selected as the power source if no mains supply is present".
This implies that, if vehicle is selected, the vehicle battery will be used as the power source when no mains supply is present.
This concerns me as I thought, except for leaving headlights on etc, the golden rule is the vehicle battery can never be drained by the habitation part of the van.

You can select the Cab battery if off EHU to power the habitation area if needed, on EHU selecting Cab battery will charge it.
If you turn of the power on the control panel then turn back on it will automaticly switch to the Hab battery

If you select the vehicle battery it will supply your habitation 12v circuits. When voltage drops to preset level, the PSU will switch back to your leisure battery, leaving enough power in the Vehicle battery (in theory) to start the engine.

Best not to select vehicle battery if not on EHU or without adequate solar input.

Yes, you can indeed drain the vehicle battery by selecting Vehicle instead of Leisure on the control panel. On the EC-series controllers, that is where charge goes to when on EHU, and that is where power comes from whether on EHU or not.

HOWEVER - Sargent have designed the system so that there is a different auto shut-off on the vehicle battery (actually implemented as an auto switch-over to the leisure battery). It is significantly higher than on the Leisure battery (10.9V instead of 9V) so that there should - in theory - be enough power left to start the engine - though I have my doubts that it would!

Hi, have the same Sargent set up as yourself and assume other pages of owner's handbook describe the same information. Not sure when selecting 4.4.3 Active Battery Sceen on EC480 control panel that 'V' battery will power any 12v habitation systems. We have witnessed that the Sun Solar panel Ammeter more often that not favours the 'L' battery more so hence failure of two 'V' batteries in less than two years. The van being in storage relies on the 80w solar panel which is clearly not enough. The incorporated battery protect circuit warning activates a warning beep if the 'V' falls below 10.9v (only useful if in the van) and switch over to the 'L'. but doesn't seem to work in our experience to prevent total discharge. Now we switch off the EC500 shut down .switch so all SP goes to 'L' and have trickle charge by way of an AA panel on the dashboard directed at any winter Sun to maintain a 12.4v charge. Also useful as a blue LED light confirms charging and connection to the vehicle by the the EOBD socket so no more under bonnet jump start connection or having to lift the floor to battery terminals. Apologies for what may seem to be load of waffle but will be interested to view comments from your OP. Oh, other experts have provided the necessary advice. Regards

OK, thanks for the feedback. 
Now I have found out, I am quite disappointed by the way this electrical system works actually.

The manual describes what everyone is saying i.e. power IS drawn from the vehicle battery when it's selected, but I just couldn't believe it works this way. I thought the vehicle battery was sacrosanct and could not be used as power source.

My 2002 Symbol could not draw power from the vehicle battery and that worked well I thought.

I'm doing a wild camping test in my back garden over the last week. Somehow, the selected battery was Vehicle at the start (last week).
I disconnected EHU and switched the EC480 off. I switch the panel on for 2 minutes every day and check the battery status.
I notice the selected battery is always vehicle and that is not what I expect from what the manual says.
I have just now manually changed the selected battery to Leisure a few hours ago and it seems to be sticking.

The system does have a mind of it's own and can switch to vehicle when it feels like it. I think I will always be nervous and have to keep checking what the selected battery is and hope it doesn't switch during the night if I'm without EHU.

I have never tried but I see no possibility of starting the van with 10.9V so that feature is useless.  Useless I say.
A fully depleted battery has an open circuit voltage of 11.7, that's FULLY depleted so 10.9V is useless to start a 2.0 diesel (unless someone has done it of course?).
A starter battery will be damaged below 50% discharge anyway.
Only thing to do is carry a jump start power bank which are quite small these days.

I am quite disappointed but 1st world problem I guess.

AutoSleepyDon wrote:OK, thanks for the feedback. 

The system does have a mind of it's own and can switch to vehicle when it feels like it. I think I will always be nervous and have to keep checking what the selected battery is and hope it doesn't switch during the night if I'm without EHU.

Well,we definitely share the same problem albeit it's our leisure battery that is favoured by said system hence now isolating the vehicle battery and maintaining 12.4v by the dash mounted AA solar panel. So less nervous than before however like you, keep a regular check. Roll on March when the 80w panel is more efficient.