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JBS BMS cycling relay once fully charged

K

kdiver58

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Joined
Feb 4, 2022
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I have a problem that is driving me nuts. I have a “JBD 7S-20S 200A 21V 24V 48V 60V 72V Smart BMS Balance Board Protection With Bluetooth” installed on my 8 cell 200 ah LiFePo4 24 volt nominal battery pack. As anyone who has one of these BMS’s it has a relay to handle the higher current.

My problem is once it fully charged, VIA a GroWatt all in one solar charge controller, the relay starts kicking and clicking in and out. The all in one is not connected to the BMS via any communication cable. It is just providing power to and from the all in one. I’m sure I have some voltage setting wrong. I can’t figure out why it keeps doing it. Maybe I have the pack charge voltage set wrong on the GroWatt all in one? These are my current settings. .. Thanks -K

FileCode 3838

DesignCapacity 20000

CycleCapacity 18000

FullChargeVol 3450

ChargeEndVol 3000

DischargingRate 2

ManufactureDate 10896

SerialNumber 0

CycleCount 0

ChgOverTemp 3381

ChgOTRelease 3281

ChgLowTemp 2741

ChgUTRelease 2831

DisOverTemp 3481

DsgOTRelease 3381

DisLowTemp 2631

DsgUTRelease 2731

PackOverVoltage 2920

PackOVRelease 2760

PackUnderVoltage 2000

PackUVRelease 2400

CellOverVoltage 3650

CellOVRelease 3450

CellUnderVoltage 2500

CellUVRelease 3000

OverChargeCurrent 11000

OverDisCurrent 54536

BalanceStartVoltage 3400

BalanceWindow 15

SenseResistor 1

BatteryConfig 11

NtcConfig 7

PackNum 8

fet_ctrl_time_set 5

led_disp_time_set 30

VoltageCap80 3325

VoltageCap60 3270

VoltageCap40 3250

VoltageCap20 3200

HardCellOverVoltage 3900

HardCellUnderVoltage 2000

HardChgOverCurrent 158

HardDsgOverCurrent 85

HardTime 176

SCReleaseTime 5

ChgUTDelay 2

ChgOTDelay 2

DsgUTDelay 2

DsgOTDelay 2

PackUVDelay 2

PackOVDelay 2

CellUVDelay 2

CellOVDelay 2

ChgOCDelay 10

ChgOCRDelay 32

DsgOCDelay 10

DsgOCRDelay 32

ManufacturerName None

DeviceName JBD-7s-20s 200 amp docan

BarCode
 
My first thought is an over voltage protection fault. Possibly at the cell level. As the cell rests the over voltage fades and releases the fault.
Any messages displayed by the BMS?

What is the charging voltage?
 
time2roll said:
My first thought is an over voltage protection fault. Possibly at the cell level. As the cell rests the over voltage fades and releases the fault.
Any messages displayed by the BMS?

What is the charging voltage?
Click to expand...
I think you are on to something. I have charge voltage set at 28.2 volts. With 100% set in the BMS at 3.450 volts per cell. No faults shown in the BMS. I think I need to set 100% at 3.5 volts and the charge set at 27.8 volts . I'm going to try that tomorrow.
 
Last edited:
I would go the full 3.650 and keep an eye on the cell voltages as the charging peaks.
Hopefully it works and balances out over a few weeks/month and can be reduced as desired.

28.2/8 is already 3.525v and is over 3.450 and even 3.500. Next step would be reducing charge voltage to about 27.50
Pressing to the very max in normal use is a bit overrated with little to no capacity gained.
 
The Fet control set to 5 seconds is probably to low, the default is 17 hours
 
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