Hello,
My newly installed Mp2 system works perfectly in Grid parallel configuration but as soon as the battery soc gets to 10% the mp2s start charging from the grid to 13% and then regulate the discharge to not feed anything into the grid until the soc gets to 10% again and the cycle starts all over again.
Has anyone an idea on what the reason behind that is?
Thank you very much,
Julian
1 Like
I have the exact same issue and i am desperate for a solution.
In my case the charging starts when the voltage drops below 50V. But there is no setting inside the ESS configuation with that threshold so I really can’t explain that issue for me.
I am using 2 pytes akkumulators with 5.12kwh each.
Hi Owen, first of all big thanks for your answer!
I already tried to change the sustain voltage from 49V to 44V. Sadly this had no effect on the behavior.
The dynamic cut off voltage is already on 42V.
Are there other options that could cause this issue?
Hello Julian
I would definitely choose a higher minimum Soc. The 5% is already very low.
What kind of battery are you using? and how big?
This 3% ‘swing’ is completely normal for the system and should protect your batteries from certain death through deep discharge.
Victron intercepts the battery at 10% … regardless of whether you set it to 5 …
This is often criticised by users who use ‘huge self-built’ banks of single cell batteries.
The 3% + - would already be a lot of mains supply for charging.
If you set it to 0% it will go down till low voltage disconnect. I have 3 ESS one 36kwh another 8kwh and a 2kwh. The 36 has a cutoff of 10% the 8 is 50% and the 2 is 20%. If the large system gets low I set the 2 smaller ones to 0% and they give all they got till shutdown.
Even if inset it to 0% (which would be at around 42V) it starts charging the battery again at around 10% until it reaches 13%. I am not able to get the Akku to 0%
@Netrange at 0% the Akku is not in deep discharge. There are plenty or research papers that confirm, that driving lifepo cells to this state does not damage the cells. Going below that voltage is a problem, but I am not even coming close to that state
If you really want full control of the system start using node red. This is a flow I have setup for Multiplus to disable charging. I let this ESS charge from 12 pm to 5 pm. You can program the logic you need and diable charge overnight or based on grid power. The function I have to check the logic also checks for sufficient power on L1.
// Get the current timestamp
var now = new Date();
var localTime = new Date(now.getTime()); // Adjust if needed
// Get the current local hour and minute
var currentHour = localTime.getHours();
var currentMinute = localTime.getMinutes();
// Define the start and end times (12:01 PM to 4:59 PM)
var startTime = { hour: 12, minute: 1 }; // Starts at 12:01 PM
var endTime = { hour: 16, minute: 59 }; // Ends at 4:59 PM
// Convert times to total minutes
var startTotalMinutes = startTime.hour * 60 + startTime.minute;
var endTotalMinutes = endTime.hour * 60 + endTime.minute;
var currentTotalMinutes = currentHour * 60 + currentMinute;
// Retrieve the current L2 power from the global variable
var L1_POWER = global.get(“L1_POWER”) || 0; // Default to 0 if not set
// Debug output for troubleshooting
//node.warn(Current Time: ${currentHour}:${currentMinute});
//node.warn(Current Total Minutes: ${currentTotalMinutes});
//node.warn(L2 Power: ${L2_POWER});
// Check conditions: if time is between 12:01 PM and 4:59 PM and L2 power is less than -400
if (currentTotalMinutes >= startTotalMinutes && currentTotalMinutes <= endTotalMinutes && L1_POWER < -400) {
msg.payload = 0; // Send 0 within the time range if L2 power is below threshold
} else {
msg.payload = 1; // Otherwise, send 1 outside the time range or if power is sufficient
}
return msg;
Hi Owen,
this is really interesting and thanks for the detailed answer and the code.
But is my request not a complete normal function of the multiplus? I just want to be able to discharge my battery to 0%. That doesn’t sounds like an extra ordenary demant 
I will keep this in my. But in the meantime I’ll try to contact victron directly and hope they can support me.
regards