Winchcombe battery death

Ever since we purchased new our first motorhome – a Winchcombe – I have been concerned about the leisure battery’s performance being so different from what we experienced in many years caravanning.   On 18 September we parked it in storage on return from holiday and ensured that the 12v system was switched off.   The AS Monitor battery reading was 13.1, on the 26^th it was 13.0, on the 29^th 12.9.   In the following days it dropped at an increasingly faster rate until reading 10.4 on 11^th October and then promptly falling off a cliff to zero.
I understand that the properties of lithium phosphate batteries may be unique but does this degree of loss not indicate that there is an unknown drain somewhere or that the battery is faulty?
Any advice will be much appreciated.

The BMS will have shut down the output voltage to protect the battery. Get it on charge and it should restart

Have you shutdown the EC700 PSU with its black shutdown button (top LH corner - not the power button on the EC700 CP) such that it is in the 'out' position and the EC700 CP is completely dead?  If not, at this time of year the EC700 will discharge the leisure battery more quickly than the solar panel can charge it.

Fixer,   Thank you.   I understand the principle of the shut down.   My concern is that, from fully charged and with no demand for power, it gets to a shut down state in a mere 23 days.
 
If this is normal I will be required to bring the battery home every three weeks to charge it and consequently expect to receive the concomitant telephone calls and emails for AS Monitor.
 
Caraman,   Thank you also.   Yes, the PSU is always shut down.   Indeed having struggled with this repeatedly for nearly two years I am now in the habit of ensuring the control panel is illuminated before shutting the PSU down as a visual confirmation that all is off.

Perhaps the next stage then is to check for stray current leakage if you prefer to investigate yourself before contacting the dealer under warranty.

1.   Turn off the PSU, and everything else you can find that the leisure battery feeds. Cover or isolate the solar panel.

2.   Remove the positive battery terminal, set it to one side, then connect a multimeter on milliamps setting between the positive battery terminal and the positive battery post. Start at high range and work down to the lowest range. Only do this once the battery has been off charge for several hours. If any current is shown to be flowing then either something remains switched on or there is leakage somewhere.

3.   If no current is flowing that might suggest a fault in the battery.

4.   If you suspect a stray current leak then the next stage is to remove each fuse in turn until this indicated leak stops. That may then give you an idea of where the leak is.

Question for somebody: On my van there seemed (to my surprise) to be no connection between the Sargent system and the Truma boiler, which as I recall (and before I changed everything) worked perfectly with the Sargent system off. With everything off I seem to recall that the Inet box LED was still flashing. If the OP has a Truma (or anything else similar) could the drain be in that area?

Does the battery have a Bluetooth app? You could monitor the current drain, if it does, probably fairly accurately.

When my EC700 PSU is shutdown, the only drain on the LB is the communication & tracker unit.  Mine was an EC632 with a non-rechargeable standby battery which drew about 10mA.  I now have an EC660-2 which has a re-chargeable standby battery and I have noticed it draws more current but not sufficiently to flatten the LB in 3 weeks.  The supply to the communication & tracker unit appears to come through The No 2 7.5A Brown fuse on the EC700.  If the supply to the communication & tracker unit is cut, e.g. by disconnecting the LB in-line fuse or the No 2 fuse, the communication & tracker unit can go into sporadic pinging rather than every 6 hours which may increase its consumption but after a couple of days it should settle back to 6 hourly pings.  If you have Sargent's tracker subscription service, cutting the power supply to the communication & tracker unit should result in a phone call from the 24-hour manned tracking station in Bedford if Inhibit Service is not activated on AS Monitor.

I've long since disconnected power to the Truma i-Net box so I can't remember what happens to it when the EC700 PSU is shutdown and I no longer have the APP mode on the Truma CP.  When the EC700 PSU is shutdown, the Truma CP goes dead and it loses its time and power source settings.  When the EC700 is turned back on again, the Truma CP springs to life with an error code until I turn it off or I turn the EC700 CP power button on.  When I want to use the Truma, I have to remember to change the power source setting to the one I want - usually EL2.  I don't bother resetting its clock.

Measuring the discharge current when shutdown is the only way to determine if the battery has an internal drain fault.
It doesn’t take much of a discharge to flatten a battery and I would imagine that 23 days isn’t abnormal unless you have some solar to assist with topping up.

Fixer wrote:Measuring the discharge current when shutdown is the only way to determine if the battery has an internal drain fault.
It doesn’t take much of a discharge to flatten a battery and I would imagine that 23 days isn’t abnormal unless you have some solar to assist with topping up.

Before I fitted a solar regulator that charges both batteries and bypasses the EC700, the LB received no charge when the EC700 was shutdown (and the mains charger was switched off or there was no EHU connection).  Providing the LB was fully charged to start with, it was fine without charge for at least 3 months.  If the OP is finding his Li LB is being discharged after 23 days, there is definitely something wrong.