Hi, here is my issue.
Everything is fine when my battery is below 100% SoC.
Once SoC 100% the mppts connected to the MPII throttle down and the MPII does not export excess power to grid (the mppts throttle down to something between 5w to 120w).
I think the issue is that the BMS doesn’t increase the voltage to 0.4 above the requested cell voltage (I can manually check the MPPT voltages and they ar 0.1v or lower above the battery.
I also had problems with charge-discharge oszilation. This is fixed now unless im using the EV-charger. I either have Oszilation Charge/discharge while battery is full and charging the EV or the MPPTs throttle down when no EV charging and battery is full.
MY system:
16s Battery with a JK BMS. The BMS is connected to the Cerbo and controls charging etc.
MPII 5000 gx
2 Victron MPPTs 135/145 with 6/9 panels
external AC connected inverter with 40 panels.
Em24 SM
Victron EV-charger
Here is what I tried:
Check that export excess DC / AC power to grid is activated. Yes it is.
Communication between BMS/cerbo/MPPTS works. All are integrated into ReCo.
Voltage/balancing of the battery high/low. Does not change the behaviour.
This is well known behaviour, you should never set ESS to 100% min SOC.
It will be fixed in the next release, currently in beta, but it is still bad practice, use keep charged instead.
What DCL and CCL is the battery sending?
With an unsupported diy BMS strange things can happen., without additional detail its just guessing.
Are any ess status codes sent? Any supporting charts or screen captures to show the behaviour?
Do you have any modifications loaded.
2 Pictures with 10 secs time bweteen. There is 9kw export from my ac inverter (not connected to the multiplus). When there is charginf of the battery with 100% Soc (this was abfter more then 1-2 hours after SoC 100% was reached) the Mppts are throttled down to 500 watts while there would be 2kw+ possible.
Even more strange is that, while there is 9kw export, the batter flips to discharge with 150w for 3-5 seconds. Sometimes up to 700w and this is exported to grid.
The mppts scale their output up and down all the time. Thiscontinues untill ther sun goes down. As said before, when SoC is less then 100% tje Mppts work just fine and the is no oszilation in the system. The batteries get charged with max CCL and excess is exported to grid.
Last weekend i managed to put the battery into Idle when SoC was reached by activating ScS, StS, and ScS. The batteries reached 100% and went idle.
But… the Mppts throttled down to 12w or so and stopped exporting excess power.
I start to get the feeling something is wrong with the voltage sensors. When activating SvS the system manages to stop oszilating but the MPII is not able to export excess. Maybe because he doesnt reach/read the +0.4 volt he needs.
Did you manage to resolve this issue? I have the same problem and cannot figure it out.
It used to work for me last summer, but I don’t know what change might have caused this.
what BMS do you use? I havent resoled it but am pretty sure I know the problem. I have a JK inverter BMS with version 15.x which cant be updated. There might be a problem with this software. I cant update it and I need to buy a new BMS. Its sad but I’m 99% sure this will fix the problem. But I haven’t ordered it till yet. Right now I changed the setting in my BMS so that it doesn’t crycle once it full, but it also turns off my MPPTS at the same time, so I lose out on some energy.
