I’m using a JK BMS which uses float voltage and three Multiplusses 8000VA. When the charge voltage of 55.2V is reached for an hour it will go to float voltage of 53.6V. When it does that, the inverters will discharge at maximum power and it ignores the maximum discharge power set in remote console under ESS. I’ve set the maximum discharge power to 14.6 kW, but when this happens it will discharge with 21 kW and gives a high discharge alarm.
Why does the systems ignores the set maximum discharge power?
Is this happening during the day with solar?
Are you able to share your settings? And are definitely using DESS as well?
It is not usual for a systen programmed with Ess to go to float during the day at least.
Yes I’m definitely using DESS. My system is trading in energy, so buying cheap and selling at high rates. Usually on a day the batteries are charged in the afternoon to 100%, either from the grid and solar or combined, doesn’t matter.
Then when the batteries sits at RCF for an hour it will go to RFV and the jk bms will lower the CVL to 53.6V to float. It will discharge for a minute or so at full power and ignores the set discharge power in ESS settings.
It looks like that Victron only uses DCL (discharge current limit) set bij de JK bms when in normal planned charge/discharge. But when de CVL (charge voltage limit) changes it will ignore any set limit either by the BMS nor ESS settings. The bms continued discharge current, which is the DCL in Victron, is set to 100A, makes a total of 300A (three batteries). During the moment the CVL changes by the bms, it will discharge the batteries with almost 400A (133A per battery) making an alarm on the bms of high discharge current which then lowers the DCL to 100A total and limiting/throttling the system.
Same problem here. V3.60-87. jk v15.41.
problem only in dess mode. in ess mode everything is fine. when the jk is in float mode it stops charging until the voltage is below the float voltage. exactly as intended. in dess mode maximum discharge (ignoring all settings (including peak shaving..)until float voltage is reached. Not ok.
temporary solution is to set RFV higher. I now have 54.4V, but will set it a bit higher tomorrow. (still a big discharge). another temporary solution is to turn off float mode in the jk. it’s not really ideal
Yes we do feed back to the grid with solar. Will it ignore any battery limits? That sounds weird. This issue only happens when DESS is turned on. When turned off the system will slowly lower the voltage by keeping the grid meter setpoint.
It is really documented as ignoring CCL.
I am wondering if maybe it may not be sending signals the same way compatible batteries do that there is some kind of mix there.
I don’t know for sure while i have JK bms i don’t use DESS. we don’t have dynamic prices so there really is no point.
Many batteries have float and absorption the same. The thought is it is cycling and cyling causes degradation not holding at a voltage, so in some cases best to not to move power in or out unnecessarily.
Here they are talking about the charge current limit. I’m talking about the discharge current limit. The DCL (discharge current limit) set by the bms is ignored.
Without DESS it works fine. (RCV-1h-100%-RFV-all ok) (CVL 55.2V → 100% → 53.6V)
With DESS on. RCV (CVL 55.2)-1h-100%-RFV (53.6V)-huge discharge (ignoring all limits) to grid until RFV (CVL 53.6V) is reached
The maximum discharge power does not apply to excess PV, and when the Multi suddenly sees a voltage in excess of what the battery should be, such as when the charge voltage is suddenly lowered, it considers this to be excess PV and feeds it in as fast as its feed-in limits allows.
To prevent this from being fed in too fast, set the maximum system feed-in power to a lower value.
The problem only occurs in DESS mode. Now in green mode. In trade mode it is the same.
I have peak shaving set to 24A import and 24A export. “Maximum inverter power is set to 15000 Watt”. If the CVL goes from 55.2V to 53.6V (battery 100%), the multiplus (3xMP8000) will supply maximum to the grid to reach 53.6V as quickly as possible. (certainly 20kW power) If there is also PV (SE17K on AC-OUT), it becomes even worse. (3x25A net aansluiting…)
The problem also occurs when there is no solar power at all.
I do not have DC PV. “met dc gekoppeld zonnepaneel overschot terug leveren” → off
So it is also much more than the peak shaving limit of 24A.
I have set the float voltage (RFV) in the bms a bit higher (54.4V) (CVL 55.2V-> 100% → 54.4V). Then the behavior is the same, only the feedin power is then a bit lower.
If I switch off DESS, it functions as expected. Charging to CVL 55.2V - 100% - CVL 53.6V - only discharge when there is demand. Exactly as expected. (instelwaarde stroomnet)
The jk-bms seems to transmit all parameters correctly.
I have now temporarily disabled float mode (jk bms). (CVL so always 55.2V). I will see what happens now.
Can you describe, what your expectation is, or where something seems to be ignored? DESS is not caring about the “DC Side”, whatever happens there in terms of voltage and things is up to the underlaying system.
You’ve configured (for DESS):
Max Import: 15kW
Max Export: 15kW
Max Discharge: 15kW
Max Charge: 12kW
I’ve checked the past days on your system and either value (feedin or charge) is correctly “limited” by these settings?
