On the 20th of December, Batrium released Watchmon toolkit 2.17.15 which includes a great new feature for inverters that support CANbus.
The new feature is called ‘Ramped Targets’ and allows the charging current to be reduced at the top or bottom ends of SOC.
I use this feature to bring down the max charge current as my battery approaches full SOC.
As you can see from the above screenshot, at 84% SOC I reduce the current from 160A -> 70A and then at 91% SOC I reduce it further to 42A and at 95% I reduce it again to 16A.
The user interface however is confusing and I don’t fully understand the #Low % field. The documentation located at: https://link.batrium.com/35-toolkit is also lacking.
In the screenshots below you can see the Target Charge Current (In the middle on the Right-Hand side) – at various SOC’s.
at 72% SOC the Target Charge Current is 160A.
Now the SOC is at 84.5% and the Target Charge Current has reduced to 70A.
Now the SOC is at 93.5% and the Target Charge Current has reduced to 42A.
Now the SOC is at 95.5% and the Target Charge Current has reduced to 16A.
I am still experimenting with these values – It seems to be a delicate balance.. The closer to the top of charge my battery gets, the lower the current needs to be to avoid going into limited mode prematurely.
In the screenshot below you can see the effect of the above. This screenshot was taken from Victron’s VRM portal. The orange line shows the charge currents throughout today (Bright hot and sunny).
What about ramping based on cell voltages!
Perhaps a more useful feature would be to ramp down the charge current based on the highest cell voltage rather than SOC (at least for Lion).. Ramping down the charge current would allow the voltages to sag a little which would avoid going into limited mode.