Hello,
I have a small solar electric installation in the Philippines. The battery voltage is now peaking at 50.8 VDC but the charge controller and inverter show 52.8 VDC. I think there could be s problem with my battery connection or maybe the CAN bus is not communicating. Are there any recomendations for how to proceed?The system consists of a 48/3000/35-32 Multiplus II, MPPT 250/70 rev 2, Pylontech 48V battery, 6x580W solar panels. Sorry. The system has a Cerbo GX. It is charging right now.
No Cerbo?
You can’t connect the Pylontechs directly to the MP2…
Yeah, you should get a GX and connect the Pylontech BMS to it.
Then, the system will take the Pylontech BMS reported voltage (and charge current limit) to operate (through DVCC)
If you have a MPPT with VeCan, get the “bigger” GX, it supports simultaneous connection of VECan and BmsCan.
Sorry,
I also have a Cerbo.
Then you should enable DVCC (Settings→System Setup→Charge Control) and select the Pylontech as controlling BMS. DVCC will then use the batteries reported voltage as a reference point.
If manually selected, you may also switch unter Settings→System Setup→Batteries, that the BMS-Values are the one outlined in your system-overview.
Ah wait, DVCC should already be “Forced On” with Pylontech - then just make sure, that the Pylontech is selected as “Controlling BMS”. Default is “Auto”, may for whatever reason pick another Battery Monitor for control.
Thank you sir. I checked the consol settings. It is set for auto but shows the Pylontech as selected.
Your multiplus is indeed measuring 52.5V, while the battery reports 50.5.
2V off is massive, but in this case it means that what the multiplus consideres as a 52.5V Chargevoltage is just equal to the voltage your pylontech has at 93%.
So, you should more likely check the connections of the Multiplus. (With DVCC enabled, the Solar-Charger won’t use it’s internal measurement, but the Multiplus’ value.)
Also check if the fuse / breaker you have used may eventually cause a 2V Voltage Drop, so the difference is not a measurement error “but real”.
(A Fuse that was once close to melt could have a significant higher resistance than it should)
Thank you. I am finally on site. Multimeter readings on the charge controller, Lynx bus and Pylontech terminals all read 50.8VFC. I see 52.4 VDC on the Cerbo GX Console under the MPPT device. Is there a setting or is it possible my MPPT charge controller might have failed?
If DVCC is enabled, the MPPT does not use its own voltage as a reference, see dognoses answer above. What voltage do you have on the DC connections of the Multiplus? Most likely you are loosing the 2V between Lynx and Multiplus. Could be on either or both positive and negative pole
We have been off grid for several months. The multimeter readings are from the MPPT Charge Controller battery terminals, The Lynx Bus and the Pylontech battery. But the voltage reported on the console under the MPPT controller is 52.4.
I did see some entries about recalibrating the system. I have attached the SOC graph for the past year. The two gaps are when our system went down for two typhoons that passed through the area here in the Philippines. I brought some conductive grease with me that is often used in marine environments. It may be that I just need to clean and re-torque the connections.
I noticed that it went all the way up to 94 percent today after I twisted the battery connections a few times, which is higher than it has been in months..
Yes, thats why im asking to measure on the DC connection of the Multiplus. Since you see a 2V voltage difference on the control, you need to find that in the real world. So far you have found that there is no voltage difference between some of the components. And since you have no shunt in the system, the main component for voltage reference for the whole system is the Multiplus.
Ok. I will check it out. Thanks again.
