Pylontech Battery Not Fully Charging

Q&A and troubleshooting
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1

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.

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2

No Cerbo?
You can’t connect the Pylontechs directly to the MP2…

1 Like
3

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.

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5

Sorry,

I also have a Cerbo.

6

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.

7

Thank you sir. I checked the consol settings. It is set for auto but shows the Pylontech as selected.

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8

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)