Any updates on this? When float is disabled in JK the system remains at 55.2v even after 2h of absorption. So the Victron charge values seems to be overruled by dvcc.
However when jk float is enables and set to 53.6v. I see a large spike in injection on voltage change.
Thats exactly what DVCC is there for. The charge voltage and current control is handed over to the BMS, the internal charge algorithms are not used anymore, hence the âexternal controlâ in all the chargers.
If you disable Float in the BMS, then it will stay at Absorption level, thats what you are telling it to do by disabling Float.
That a system is actively discharging the batteries when the charge voltage limit is changed downwards is also somewhat normal. The BMS tells the Victron system that it wants the battery voltage at 53.6V now, so Victron is doing what it can to achieve this. There has been discussions about this behavior, should it actively discharge or simply wait for the voltage to come down naturally? AFAIK theres not been a conclusion. But if you really dislike the short discharge (i mean for me its like 2s of export to grid until the new voltage level has been reached already, i dont worry about that) then i guess you would need to do something against it on your own, for example through NodeRed.
For me itâs a 1,5-2kwh discharge starting at 15kw of discharge rate tapering down.
Takes roughly 5min of active discharge.
2kwh out of a 48kw battery seems a bit mutch
That indeed is a lot. You can look into disabling DC-feedin or set DCL to zero when the CVL has just changed downwards for example, or maybe gradually reduce CVL over time
As the name suggests, Andi from off-grid-garage doesnât have a grid connected system and so he doesnât have this problem. For gid connected systems (with feed-in) use these settings in your JK-BMS:
You should be fine with above settings.
PS Calibrate your JK BMS current and voltage once every few months, these are mostly way off
I have an Multiplus II GX and a battery with a JK BMS that controls the requested voltage via DVCC
And i also have a DC-coupled MPPT 250/60 that follow this regime via an VE connection
Further i have enabled âDC-coupled PV - feed in excessâ
But what i see after the battery is full and the float voltage is requested, is a very restless charge/discharge pattern.
Where it is pingponging between plus and minus 20 to 30 Ampere every second.
When the requested voltage drops to 53.6v (float) this is nicely maintained by the system.
I do have a giant discharge current peek when the voltage drops from absorption to float.
But i solved this by disabling dc feed in excess for 15mim, the battery voltage has then dropped to 53.6v naturally
The current ping-pong start when i re-enable feed-in excess. The battery is maintained at 53.6v (float) but the current goes al over the place
I donât think this is exact what this topic is about but nickdb closed my topic and he sent me here.
Hi Warzel,
As for me, I havenât enabled âDC-coupled PV - feed in excess,â so I canât help you with your issue.
Tell me, are you in ESS mode? Is the MPPT set to External Control?
If so, can you tell me what voltage youâre seeing under Device > MPPT 250/60 > Grid Operation > Charge Voltage? (in float mode on JKBMS)
Thanks in advance
Yes i am in ESS mode
i do not have: Device > MPPT 250/60 > Grid Operation > Charge Voltage
I do see: Devices > MPPT 250/60 >
I do have an voltage reading, it is 54.00 V while the system is in Floatmode. So 0.4V higher then the requested 53.6V floatvoltage
So you set the RFV value to 3.375 in the JK-BMS.
Is your BMS cable a Victron Type A cable connecting the Cerbo to the JK-BMS? or are you using any other communication method?
