Voltage Discharge Characteristic for Load Current

[spairo1741]

• I set my parameters in the config.c and eeprom.py files (2800, 2700, 2100, 2000, 1300)
• I generated eeprom.hex and uploaded it to the attiny824
• I connected an electronic load to the battery.
• At a load of 1.25 A, the electronic circuit breaker tripped.
• The 1.24 A load was active for 30 minutes; the polymer fuse didn't trip.
• The BMS acted as if it didn't recognize my parameters, dropping the voltage to 1.7 V, while my parameters were 2.00 V
• What did I do wrong, and how can I fix it?

eeprom.hex.log
:02 0000 04 0081 79
:10 0000 00 3773 0500 0700 F00A 8C0A 3408 D007 1405 7E
:04 0010 00 0A003AA9 FF
:04 0000 05 00810000 76
:00 0000 01 FF

[spairo1741]

• The charging current and cut-off voltages were set.
• Due to large voltage drops, the voltage readings at the output connector were incorrect.
• When reading the logs, everything was fine.

lto-bms,id=0005 uptime=9660i,v_batt=2347i,v_load=2162i,current=677i,E_dis=3877i,E_chg=0i,charge=1569i,temp=320i,gain=8i,state="BMS_STATE_DISCHARGING"
lto-bms,id=0005 uptime=9720i,v_batt=2345i,v_load=2160i,current=677i,E_dis=3904i,E_chg=0i,charge=1580i,temp=320i,gain=8i,state="BMS_STATE_DISCHARGING"
// v == 2.16 v
lto-bms,id=0005 uptime=9780i,v_batt=2376i,v_load=2367i,current=0i,E_dis=3910i,E_chg=0i,charge=1583i,temp=317i,gain=16i,state="BMS_STATE_IDLE"
lto-bms,id=0005 uptime=9840i,v_batt=2378i,v_load=2370i,current=0i,E_dis=3910i,E_chg=0i,charge=1583i,temp=314i,gain=16i,state="BMS_STATE_IDLE"
lto-bms,id=0005 uptime=9900i,v_batt=2379i,v_load=2371i,current=0i,E_dis=3910i,E_chg=0i,charge=1583i,temp=312i,gain=16i,state="BMS_STATE_IDLE"

[spairo1741]

I noticed that one LTO module doesn't enter the BMS_STATE_IDLE state,

• without charging and without a connected load, it enters the BMS_STATE_CHARGE state with a current of 3 or 5 mA.
• What could have happened?

lto-bms,id=0005 uptime=300i,v_batt=2603i,v_load=2432i,current=676i,E_dis=62i,E_chg=0i,charge=23i,temp=314i,gain=8i,state="BMS_STATE_DISCHARGING"
lto-bms,id=0005 uptime=360i,v_batt=2625i,v_load=2627i,current=3i,E_dis=65i,E_chg=0i,charge=25i,temp=312i,gain=16i,state="BMS_STATE_DISCHARGING"
lto-bms,id=0005 uptime=660i,v_batt=2629i,v_load=2631i,current=3i,E_dis=66i,E_chg=0i,charge=25i,temp=307i,gain=16i,state="BMS_STATE_DISCHARGING"
lto-bms,id=0005 uptime=720i,v_batt=2629i,v_load=2631i,current=5i,E_dis=66i,E_chg=0i,charge=25i,temp=307i,gain=16i,state="BMS_STATE_DISCHARGING"

[slintak]

The issue with the firmware not entering BMS_STATE_IDLE is likely caused by a bug that I fixed recently.

There was an extra state (BMS_STATE_OVLO_AC) in the state string table, which caused a mismatch between state values and their names. This was fixed here.

The fix is included in firmware v1.3 (released for PCB revision C):

If you are using older hardware (Rev. B), you can fix this by removing the BMS_STATE_OVLO_AC entry in config.h so the states are aligned again.

[spairo1741]

-please close the topic, the problems have been solved.