Victron multi plus not getting 100% on SOC when on shore power
Background configuration:
We are a boat moored in a marina using ( approx 230v and 30amps) shore power. We have 4 new Victron super pack 12v 100ah batteries connected in parallel. We have an additional lead acid 12v 100ah which is the starter battery… so 5 batteries in total.
We Have victron Orion XS, Cerbo GX, lynx distribution bus bar, smart shunt, a Rutland wind generator controller connected to a 100w solar panel and a Victron 75/10 MPPT connected to a 100w solar panel.
Settings:
Multi-plus (12v 3000w 120va) … Most of the setting are on default except for
General:
System Frequency - 50Hz
AC1 input current limit - 16 amps
Charger:
Charge current - 120
Absorption voltage - 14.2
Float voltage - 13.8
Lithium batteries. - on
Inverter:
Output voltage - 230
Ground relay - on
AES. - Off
Problem:
When on shore power, there was a time when left overnight with just our cooler on, the batteries state of charge would be 100% and the voltage would be around 14.1v or 14.2
Now in the morning when checking the state of charge is around 92-94% and the voltage is around 13.3 or 13.4
The multiple plus also displays “float” in this state and so is not charging the batteries … why is it not bulk or Absorption ?
We have tried various combinations of settings with no change in results …
What are we doing wrong ?
Okay, okay panic over … it seems my beginner understanding had
clouded my judgment. After posting this problem i continued my research on the understanding of lithium batteries Vs lead acid (incl AGM GEL, etc.) and Victron charger settings (Multiplus). I found resources (links at the end) explaining the Bulk, Absorption, Float stage including the extra equalisation stage on a graph in detail. Further I needed to know/understand how to top balance lithium batteries. In studying my problem I ran into the usual misinformation and user opinion confusing the issue, until I discovered, “off the grid garage Australia” doing an actual test … Titled “Lithium cell in float charge will destroy your battery” ?
As it turns out I could solve my problem by simply changing my multiplus settings to :-
Charger Tab:
Charge current - 120
Absorption voltage - 14.2
Float voltage - 14.1
Lithium batteries. - on
The SOC charge was displaying 64% and the charger was idle at 13.35v. By making this change the charging cycle restarted and upto 150 amps was displayed . … as the voltage increased the amps dropped significantly until the volts reached absorption (14.2) the current fell back to 0.0v (zero). Just as it was explained and demonstrated. I’m currently watching my changes closely. The SOC is now at 99% after half a day with various loads. I’m going to further test my settings as i want to test the float voltage at 13.5v as this is the max state on the batteries data sheet. However, I believe the current setting are my systems sweet spot.
Resource :
Off grid garage Australia
DIY Solar Power … Will Prowse
Solar Solutions … Jesse Gorter
Best Regards Everyone