Do you use SYSTEM SHUTDOWN?

Today my Remote Control didn't work so I had to use the key to open the door.
I tried the ignition and a couple of dashboard lights came on dimly so any attempt to start the van was fruitless. The display on the Sargeant controller showed the vehicle battery as being at 2.6v!
For various reasons, I had not had the EHU connected up since my last trip just over 2 weeks ago and I believe that I should have used the System Shutdown switch on this occasion as both the batteries can be drained in this length of time despite nothing electrical having been left on.
I've now connected the EHU and after a few hours charging I have been able to lock the doors with the remote.
I'm hoping that the battery will charge up overnight - I will try to start the van in the morning.
The van is only a few months old and I don't remember being told about this System Shutdown switch when I bought it but as I usually leave the EHU on, I've never had a battery problem.
I'd be interested to hear about when you use system shutdown - is it ok to leave it for a few days without EHU or should it be shut down whenever the van isn't being used?

John

Yes - it should be used if the van is going to sit unused for a while.

But if it was the vehicle battery that went flat it's not likely to be anything on the Sargent side of things that was responsible - the Sargent unit would have done an auto-switchover (to the leisure battery) or an auto-shutdown long before the battery got as low as that. IIRC the switchover point is 10.9 Volts, with shutdown at 9 Volts!

It's far more likely to have been the vehicle alarm, or a tracker or permanently wired USB power supply or something similar (possibly the cab headunit, if the original headunit has been replaced).

Your vehicle battery may never recover from such a low voltage. Keep a close watch on the voltage drop once you have stopped charging

I just wonder whether I can trust that reading from the Sargent controller as I think other safety measures should occur before the voltage drops that much. I should really have checked it with a multimeter as well. It all seemed to be back to normal after a night on the EHU.
I will start checking both batteries more regularly with a meter I think.
John

I'm not sure what other safety measures you are thinking of.

Most of the loads on the vehicle battery don't pass through the Sargent controller, so it can't do anything about them. The only loads it can control are the ones in the habitation parts of the vehicle. If the battery drain is elsewhere (e.g. almost any load supplied/switched from the cab) then the vehicle battery will go flat.

If the vehicle battery was so flat that it could hardly light the dash warning lamps then I would be inclined to believe the reading of 2.6 Volts.

I understood that my vehicle battery went flat because I hadn't switched the system shutdown and that the system shutdown disconnects all the habitation systems.
Also, I thought I'd read that if the leisure battery is low, power is drawn from the vehicle battery instead but that if this drops to about 10v then this stops in order to protect the vehicle battery and I assumed that this was automatic.
I think I need to re-read the manual but in the meantime I think it will be safest to keep the EHU on and if I'm driving, switch the system shutdown.
John

As I've already said, your vehicle battery probably went flat due to something completely unrelated to the habitation electrical system.

The examples that I gave at the end of my first reply are ones that the Sargent unit cannot control, so if those or any other similar power drain exist, the vehicle battery will go completely flat eventually. In that case it doesn't make any difference whether the Sargent unit is powered on or in "system shutdown" - the vehicle battery will still go completely flat.

Agreed, you can use the EHU to compensate for any drain on the vehicle battery, but if you are forced to leave the van for some time somewhere where you cannot hook up, you are likely to come back to find a flat vehicle battery unless the cause of the problem is found and fixed.

I have a quite new Symbol and experienced a flat vehicle battery after layup last Winter. I am thinking of, next Winter, disconnecting the vehicle battery and probably the habitation battery as well. Does this make sense? Will I be able to lock the vehicle? Are there any resulting problems with this idea if the vehicle is not used for a month or two?

Paul Saunders wrote:I have a quite new Symbol and experienced a flat vehicle battery after layup last Winter. I am thinking of, next Winter, disconnecting the vehicle battery and probably the habitation battery as well. Does this make sense? Will I be able to lock the vehicle? Are there any resulting problems with this idea if the vehicle is not used for a month or two?

You cannot lock the passnger door without central locking!  And you cannot lift the bonnet without opening the passenger door to get at the release.  I had a flat vehicle battery last winter and discovered this nonsense the hard way!  I guess that it is a relic of the original Boxers/Ducatos being LHD.
I have wondered if I can swap the door handles so that the one with the key is on the passnger side instead of the driver's side.