The “limit managed battery charge voltage” is currently set for 13.9 volts. There are 3 MPPTs. We see that the solar output seems to be system limited. If we disable one MPPT, the total power seems to stay about the same, the 2 remaining MPPTs power goes up. If we raise the “lmbcv”, the delivered power goes up. It seems that theDVCC is causing the power to limit too early. What have people found is a good way to set this up?
Thanks!
This is not a parameter intended for permanent use.
If has a specific purpose.
The battery should send the required cvl. It should only need to be overruled in exceptional cases.
It makes sense that this limit might be a work around, and that the Epoch BMS such be trusted. What is the purpose of the limit, and how is it normally used? The limit was put in place to stop alarms from the Epoch BMS that were happening during initial system commissioning. It may have been intended to be used as a temporary fix.
It was developed to allow for new batteries to be balanced properly and to avoid overcharging, originally for pylontech.
The limit max charge voltage is intended to cure the problem of the BMS allowing the system voltage to rise to the disconnect point - yes, originally noticed with Pylontech. This setting, and the related limit max system charge current, are there for battery and system protection, as an easy tweak to stop battery overcharging leading to disconnection.
It was predominantly to deal with new unbalanced batteries, where one cell would go high causing issues, pylon’s were stubborn and could take time to resolve, this is now unnecessary with the new pylon charge algo in dvcc.
It is still relevant for dealing with similar issues on other packs but purely setting it with no problem to fix isn’t the best of ideas.
I have seen more cases of it negatively affecting systems by being set incorrectly than those it has helped.
The new trend to set it the same as the battery CVL is also thoroughly pointless.
If a manufacturer does not want it enabled and you don’t have problematic behaviour to address, it should be left alone.
Yes, this is due to the 50mA balancing current which is weak for solar charged systems.
Epoch seems to recommend setting the “limit managed battery charge voltage” to 13.8V
Is it the case that there should be no limiting by the Cerbo until the maximum charge voltage is reached?
We see verbose limiting the solar power well before the limit voltage is reached.
We see the following behavior:
DVCC limit managed battery charge voltage is on.
Summarizing the data below, increasing the DVCC maximum charge voltage from 13.8V to 14.0 increased charging current and power from the MPPT, even though the battery voltage is at 13.4V. We
Is that the expected behavior?
Maximum charge voltage 13.8v
Battery voltage 13.40V
Battery current 10.9A
Solar power 437W
Maximum charge voltage 13.9v
Battery voltage 13.41V
Battery current 18.5A
Solar power 526W
Maximum charge voltage 14.0v
Battery voltage 13.41V
Battery current 24.1A
Solar power 629W