mrzed001
Voice of reason
This happened to one of the members in the Hungarian off-grid community.
OP has two 24V LiFePO4 packs connected paralel :
- 280Ah EVE cells with JK BMS
- 160Ah with cell level BMS
Batteries where charged by:
- MPP Solar 3024GK inverter with 6 solar panels
- Epever 6420AN MPPT with 4 solar panels
So really a simple DC coupled system
The system is running for more than a year now.
With smart home so if batteries are full then extra load (heater) is starting automatically to consume the extra sun power.
But yesterday suddenly battery voltage rises to 34V and later 36V.
MPP Solar 3024GK is in FAULT 08: DC BUS voltage too high.
Inverter seems to start but without MPPT. Some capacitors are blown inside.
The smaller LFP pack is heavily damaged. Cell level BMS could not protect it.
There was no fire.
The larger LFP pack has now a JK BMS (old pic with the old Daly), and it survives
The Daly BMS was replaced to the JK BMS after the post here, where the Daly did not protect the pack after MPPT failure.
JK BMS did disconnect the charge as it should (and survived):
( For some reason Cycle capacity is counted wrong in the JK BMS for some time. No clue why :D )
We still do not know the cause of the error.
Maybe MPP Solar inverter's MPPT gone to short?
We tested, no continuity between battery and MPPT inputs.
MPP Solar was set to 16-Charger source priority = Solar+Utility.
There was a firmware problem when this caused the DC bus voltage to slowly creep up to 500V (in a rainy day) and the inverter stops with the ERROR 08.
But the inverters usually survive this without damage
So still no clue what caused this.
TLDR; 2 batteries, 2 MPPTs charging it, one is damaged and one battery overcharges
OP has two 24V LiFePO4 packs connected paralel :
- 280Ah EVE cells with JK BMS
- 160Ah with cell level BMS
Batteries where charged by:
- MPP Solar 3024GK inverter with 6 solar panels
- Epever 6420AN MPPT with 4 solar panels
So really a simple DC coupled system
The system is running for more than a year now.
With smart home so if batteries are full then extra load (heater) is starting automatically to consume the extra sun power.
But yesterday suddenly battery voltage rises to 34V and later 36V.
MPP Solar 3024GK is in FAULT 08: DC BUS voltage too high.
Inverter seems to start but without MPPT. Some capacitors are blown inside.
The smaller LFP pack is heavily damaged. Cell level BMS could not protect it.
There was no fire.
The larger LFP pack has now a JK BMS (old pic with the old Daly), and it survives
The Daly BMS was replaced to the JK BMS after the post here, where the Daly did not protect the pack after MPPT failure.
JK BMS did disconnect the charge as it should (and survived):
( For some reason Cycle capacity is counted wrong in the JK BMS for some time. No clue why :D )
We still do not know the cause of the error.
Maybe MPP Solar inverter's MPPT gone to short?
We tested, no continuity between battery and MPPT inputs.
MPP Solar was set to 16-Charger source priority = Solar+Utility.
There was a firmware problem when this caused the DC bus voltage to slowly creep up to 500V (in a rainy day) and the inverter stops with the ERROR 08.
But the inverters usually survive this without damage
So still no clue what caused this.
TLDR; 2 batteries, 2 MPPTs charging it, one is damaged and one battery overcharges