I have an RV that during the winter period stays connected for long periods to shore power.
I wanted to test the solar / wind priority and I in the MultiPlus have setup:
“Limit internal charger to prioritize other energy sources” : Check
“Sustain voltage” 13.00 V
I forced an initial charge to 100% (That I needed to stop manually due to other limitation in the “Solar and wind priority” Victron solution
Since then, as expected I can see the voltage falling (consumed by the DC loads) towards the target of 13.00V
Similarly I can see the state of charge falling (since solar can’t contribute enough in these cloudy days)
But the weird thing is that even when Voltage hits aroud 13.00 (and I can see the Multiplus keeping it at that voltage), the state of charge keeps falling.
Is this normal? would the SOC eventually stop falling? Or is it a wrong reading/calculation?
See SOC falling (RED) , Voltage staying around 13V (Blue) and the MultiPlus Watt output (Orange)
That is the default value. But I can indeed try to change it
I was puzzled about the fact that 13.00V is being maintaned fine while SOC fall, but maybe it will stop at 30%?
While if I implement your change it will stop at 70%
Yeh, Perfect World charts. Good for a guide, but get affected by charge/discharge. You’ll find the sweet spot if you experiment. That is, once you decide how much room you want to leave in the batts for your priority chargers…
It looks like the sustain voltage hasn’t actually been triggered yet. (Internet diagnosis beingwhat it is)
13v is the red line and the blue line is your battery voltage.
So technically you arent at 30% yet.
The discharge curve is really flat in lithium, maybe you are just hanging around that section.
In the vrm or gx are the consumer AH shown to be going up?
I have risen the sustain voltage to 13.1V and now SOC is stable 39.5% Almost spot on matching the 40% reference from the picture I posted earlier.
So it seem all is good
@lxonline & @JohnC
I have a special case where I would like to change the sustain voltage from 13.1 to 13.5
The reason is that I have a battery maintaner (to keep the starter battery topped up) that will kick in only when the leisure battery is 13.5
The float voltage is set to 13.6 in both the MPPT and Multiplus. Do you see any problem to keep the battery at 13.5 using sustain? Accourding to the chart above it would represent between 99% and 100% SOC.
Would it cause any problem to the battery
You really need to ask your battery manufacturer how best to treat them. They may well need some time periodically at a higher V to balance the cells, but not all the time?
And this ‘maintainer’ might be just a switch?? A Pb starter batt will still charge at 13.2V, just takes a bit longer…
Thanks, for the suggestion. I will contact the battery manufacturer.
Regarding the maintainer, it’s this one. Designed for using Leisure Lithium battery to keep the vehicle one topped up.
But it only kicks in when the voltage of the lithium batter is >13.5
