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diy solar

Expanding existing system (Growatt sph5000 and 2x pylontech US2000)

gokalex

New Member
Joined
Jul 22, 2022
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9
I have this setup:
Growatt SPH5000 Hybrid Inverter connected to 2 Pylontech US2000 Batteries with BMS communication between battery and inverter.

The Pylontech US2000 battery uses 15s 50Ah LiFePo4 cells.

I worry about the BMS communication.

I can't disable the COMS from the Pylontech US2000 Batteries because the inverter will not work without it.

If i set the inverter to use no COMS i need to put it in Lead-Acid battery mode, but it has a minimum charging voltage of 55V (3.666V for a 15s battery, too high!)

I was wondering if I could keep the COMS enabled on the Pylontech US2000 Batteries and just parallel the new system, but if the battery/inverter find out that there is a new battery connected it might not work well.

For a test, today i had removed the communication cable between the two us2000 batteries and turned the system back on, during the day it charged both batteries (at a reduced rate, 25A instead of 50A, since only 1 BMS was connected to the inverter it set the charging current to only 25A), but when it came time to discharge the batteries in the evening nothing was happening, and there was a BMS error on the inverter logs. So i turned everything off, connected the coms cables, and turned everything back on. after that it started discharging the batteries correctly again.

This test kind of tell's me that just paralleling a new 15s battery will not work 100% (it will charge but it will not discharge)

Is there anyone that found a solution for a problem like this?

(i could buy other pylontech batteries but they are much more expensive than the rest, the us2000 50Ah is 1200euro from local resellers, or around 1000 if i look on ebay)

Thank you,

Alex
 
Hello,
Does anyone have any idea on how to help me?
Like a custom firmware that unlocks voltages?

Thanks
 
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