The 54% SOC is taken from your
Victron BMV I would assume? The
battery has no internal SOC value that can be accessed (I am stating this to preempt suggestions that you check the
battery itself - this is something you cannot do).
What I suspect is happening is the
battery did go virtually flat and the SOC reading is out of sync with the true state of charge of the
battery. The
battery monitor and the presented SOC is in a way just a guess at what is left in the
battery. It is usually a very good guess, but it can creep out of kilter gradually.
Victron themselves recommend the monitor is re-synced on a monthly basis but few people do that, and don't really need to typically, but it can be useful to do. For example, one of my BMVs goes out by around 10% gradually and I notice when the
battery doesn't take any more charge but it is reading in the low 90's for the SOC, so I then resync to 100%. In my case it is being pessimistic with the charge level - in your case it is being optimistic.
Another reason why it could be out is as Neil suggests - when the
BMV resets to 100% on a power loss. This results in a very optimistic
battery SOC. I usually change this setting on the
BMV so it would reset to "--" instead of "100%", and more recently with the
BMV-712 or
Smartshunt, change the setting so it remembers the SOC on a restart (by far the most useful, but only available on Bluetooth enabled Monitors). I think you have this setting like that in your setup, but it is possible you don't?
If you want to check, run the VictronConnect app, click on the little gear icon in the top right and chose "
battery settings" and then look towards the bottom for the item '
Battery SOC on Reset' and what it is set to. I would expect it to say "Keep SOC" like in my screenshot below
View attachment 146727
The possible choices for the
Smartshunt and
BMV-712 are below:
View attachment 146728
Keep SOC is now the default, but it used to be "Set to 100%" before the Keep SOC was available and that old default could cause issues with what is being told to the user.
You, Annie, will have the option above, but just to restate for someone else with a non-Bluetooth
Victron Monitor (including ones using the BT Dongle - that doesn't count), the "Keep SOC" will not be available and instead you are stuck with the older options....
View attachment 146730
(My suggestion for anyone with limited selection as shown above... always turn that "
battery starts synchronized" off, as I have done)
What would be interesting is what is the voltage showing on the
BMV when you are seeing 54% or so? At 54% you should be at a voltage of say 13.1V or higher, but I bet it is middling 12.7V or so?
What I would do is do exactly what Neil is suggesting and plug the van into EHU for a full day - with your setup, you should be able to recharge from totally dead in less then 5 hours so a full day will give extra time for any final trickling just to make sure you are full.
But I would do one step further and when it is plugged in and charging, keep an eye on the
BMV and when it gets to 100%, leave it plugged in and have a look at the current it is reading that is going into the
battery .... if the
battery is at 100%, the current should very very quickly drop to virtually nothing but I suspect you will continue to see 50A+ going in for a fair time still. If that is the case, it does mean the
battery state of charge was not as reported and give you the reason for why you were losing the 12V.
By leaving it plugged in until the current is no longer a high value, you will have replenished the
battery fully and the
BMV Monitor will also have reset and corrected itself in effect.
Hope that helps. If you want to give me a call to discuss, please feel free
)
