question

Paul B avatar image
Paul B asked

Multiplus II battery voltage SLOWLY creeping up past set values

The BMS has switch to Battery overcharge and the red led is on in the VE-BMS unit, now during the writing of this and switching the monitor bach to the BMV 700 the voltage reading has increased to 56.8v yet we are in float mode and the voltage should be going DOWN to 54.5 NOT UP

I have already had a runway voltage at 65 volts before and am suspecting that the voltage will just keep on increasing


now if I remove the OVER voltage condition and reduce the charge voltage back to 56V then the over voltage condition issue is removed from the VE-BMS then things return to normal


MP II FW459

Lithium LIPO 20Kw battery bank

Venus GX FW 230/50

BMV 700 FW 3.10

VRM fully active

ESS active

AC sensor ACTIVE

grid conected

Grid tie solar active as per the screen shots.

79watts and 1.7 amps still being added (per BMV700

Settings has DVCC turned on


voltage NOW 56.8V amps 1.6 BMV700

switch monitor to multiplus Voltage 56.8 amps 0.0


VOLTAGE NOW 56.9 on the multiplus amps 0.0

switch back to BMv voltage 56.9 amps 1.6amps


SO in Summary

it seems that if the VE-BMS is triggered with a OV protection and the red LED comes on then the charging on the MP2 does not fully stop it continues to supply about 1.5 amps and as the lithium's are full the voltage just keeps going higher

well thats my interpretation so far.




The below is the VE config setting in the Multiplus II


The below screen is with the Multiplus selected and its showing ZERO amps going in and the voltage is down at 54.7



Below Screen capture is with battery monitor BMV 700 selected and it shows a small charge going into the batteries of 1.5 amps


Multiplus-II
1558770839869.png (39.0 KiB)
1558770936080.png (40.0 KiB)
1558771104065.png (17.5 KiB)
1558771272194.png (109.0 KiB)
1558771915730.png (39.9 KiB)
2 comments
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Paul B avatar image Paul B commented ·

Interesting is that the VRM was also showing 0 amps the same as the MPII internal monitor when the BMV was showing 1.5 amps.


Currently without the OV trigger the amps on the VRM are showing correctly and at the same value as the BMV.

???? Hmmm

0 Likes 0 ·
Paul B avatar image Paul B commented ·

Some more testing but now not so sure its a BMS OV Issue


turned the maiuns off and discharged the battery some then put the mains back on.


now while the BMS was under its balancing setpoint the amps while on absorbtion dropped to zero however as the BMS setpoint of 3.5v per cell was reached the amps slowley climed upto 1.5 amps which is the V bypass setting of my BMS uniut and as the all balanced to 3.5 the amps raised to that lkevel so to maintain 56volts then a 1.5 amps current would be ok as this is what the BMS was using. however the Voltage slowly started to raise again 56.1 56.2 up to 56.4 amps stayed at 1.5 as the cells BMS was trying to reduce the voltage back to 3.5

now when the system switch to float it should have trigged the float voltage setting and dropped the voltage, BUT it did not its stayed at 1.5 amps and 56.4 and the voltage kept going up as time progressed


So I cant find a reason for this and it should not be happening


really even under absorption it should not have increased over 56.0 plus or muni 0.1v is ok but to keep raising HMMM



0 Likes 0 ·
1558780828114.png (39.3 KiB)
1 Answer
Paul B avatar image
Paul B answered ·

Today my Venus Fw was upgraded from 230-50 to 230-51

However there are no release details, so I don’t know what was fixed and if its related


Set voltage for absorption is 56.3v


I also moved the Assistant setup around putting the ess first


DCVV is still on


The OV BMS protection has just triggered and all cells are now over 3.5 volts each, but charging has NOT been fully turned off its still slowly increasing the voltage now 56.4


After 5 min its now turned off and I am now seeing a discharge


I don’t know if there are changes in the FW 230-51 or its reposition of the ESS to first place in the list


But today the voltage runaway seems to have been solved .

will update if something else happens re this

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.