Soc Calibration - Chargery BMS8T Series Owner's Manual

LiPo & LiFe, LiTo Battery Management System

SOC Calibration

The program calculates SOC according to the power charged or discharged from battery. Users need to setup
battery power (WH) and battery capacity (AH) when turning on the BMS for the first time. After charging
to Maximum voltage or discharge to minimum voltage, BMS will complete the SOC calibration and display
accurate SOC. The details are as below.
WH = (Cell Voltage X AH rating) IE: 4 cells X 3.25 volts = 13.0V. 13.0V x 280AH = 3640WH
1. Connect all cells and accessories.
2. Turn on BMS, choose battery type, cell count is automatically identified by the BMS, press START or
waiting for 8 seconds, BMS will start and display all cell voltages.
3. Press START for 3 seconds to enter setup configuration screen.
4. Continue to setup "over charge protection(P) voltage" to Maximum value according to cell datasheet.
Generally it is 4.20V for LiPo, 4.15V for Li-ion, 3.65V for LiFe, 2.70V for LiTo battery.
5. Continue to setup "over discharge protection (P) voltage" to minimum value according to cell
datasheet. Generally it is 2.75V for LiPo, 2.50V for Li-ion, 2.5V for LiFe, 1.50V for LiTo battery.
6. Continue to setup battery AH and WH according to battery datasheet. WH can be calculated based on
the formula above or setup according to cell datasheet.
7. Continue to setup "Low SOC cut off" to 0. The setting is used for SOC calibration while discharging.
8. Continue to setup "over charge current‖ and "over discharge current" according to your particular
application requirements.
9. Others can be setup later, but make sure battery can be charged or discharged normally.
10. Press START for 3 seconds, quit Program Setup, LCD display SOC, WH and AH, SOC is estimated based
on battery voltage. WH and AH is calculated according to WH and AH settings. Take a 16S 10AH LiPo
battery as a sample, If SOC estimated is 20%, AH setting is 10AH, WH setting is 592WH (3.7v
, the WH reading will be 118.4WH, and AH reading will be 2 AH.
10AH=592WH)
11. Start to charge, with the charging time increased, the SOC, AH and WH will increase, till the cell average
voltage reach 4.2V (it is over charge protection voltage setting), the SOC will display 100%, AH reading
is 10AH, WH reading is 592WH. Actual power charged may be not 592WH, it is normal, the power (WH)
difference is caused by SOC tolerance based on voltage. The BMS calibrated the difference and display
accurate SOC.
12. Or start to discharge, with the discharging time increased, the SOC, AH and WH will decrease, till the cell
average voltage reach 2.75V (it is over discharge protection voltage setting), the SOC will display 0%, AH
reading is 0AH, WH reading is 0WH. Actual power discharged may be not 0WH, it is normal, the power
(WH) difference is caused by SOC tolerance based on voltage. The BMS calibrated the difference and
display accurate SOC.
13. Stop charging or discharging, the BMS will display accurate WH, AH and SOC, when starting to discharge
or charge again, the BMS will display actual power charged or discharged. It will be very accurate.
Notes:
In SOC calibration, or in first charging or discharging, "over charge protection(P) voltage" and "over
1.
discharge protection(P) voltage" setting are very important, it must be maximum cell voltage and
minimum cell voltage separately. The voltage setting can make sure the WH and AH reading after
calibration are accurate.
2. When you turn off BMS, the actual SOC, WH and AH will be saved, and displayed when you turn on BMS.
This feature avoids re-calibrating SOC.
3. As Charge and Discharge cycles increase, the battery capacity will be decreased, that is to say, the actual
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