Product Introduction; Lithium Iron Phosphate Battery; Battery Management System (Bms); Sleep Mode - Carbest Li100 User Instruction

4. PRODUCT INTRODUCTION

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4.1 LITHIUM IRON PHOSPHATE BATTERY

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The lithium iron phosphate battery (LiFeP04) is the safest of the mainstream lithium battery types.
The nominal voltage of a LiFePO4 cell is 3,2V. A 12,8V LiFePO4 battery therefore consists of 4
cells connected in series.
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Compared to the traditional lead-acid battery, the LiFeP04 battery has higher densities of energy
and power. Lithium batteries are light on weight and smaller in size.
ES The lithium iron phosphate battery has a higher depth of discharge than lead-acid batteries:
100% vs. 50%. This results in a higher usable capacity. And it has a very low self-discharge rate.
Compared to lead-acid this is 10 times lower.
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4.2 BATTERY MANAGEMENT SYSTEM (BMS)

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A BMS (Battery Management System) ensures safe discharging/charging of the battery and
monitors the individual cells of a battery pack. By balancing unequally charged cells during
charging, cell drift is reduced. Regular balancing ensures optimal capacity utilization while
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preventing excessive aging of individual cells.
In addition, the BMS monitors the individual cell voltage and interrupts the charging or discharging
process in the event of overvoltage or undervoltage of an individual cell. By maintaining the
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operating parameters, the cycle stability, i.e. the service life of the battery, is increased.
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The BMS performs the following tasks:
• Monitoring the battery
• Providing battery protection
• Estimating the battery's operational state
• Continually optimizing battery performance
• Reporting operational status to external devices
Carbest LiFePO4 batteries always come with a built-in battery management system (BMS) that
protects the cells from many strenuous circumstances to protect the life cycles of the cells and
the electrical system from potential damage. The integrated BMS protects against the following
conditions:
• Over-Voltage Protection
If an individual cell voltage exceeds a prescribed threshold during charging, the BMS will prevent a
charge current from continuing. Discharge is always allowed under this condition.
• Low-Voltage Protection
If an individual cell falls below a prescribed threshold during discharge, the BMS will prevent
further discharge. Although the battery is in „low-voltage disconnect" mode, it will still allow a
charging current.
• Over-Current Protection
After exceeding the over-current protection value for 3s, BMS will cut off the MOS automatically.
After 10s, the protection will be automatically released, and the discharge switch will be turned on
again, and the lock will not be automatically released if it occurs consecutively for 3 times.
(If there is any normal charging or discharging process, the count will be cleared).
Release conditions:
1. Remove the load (for > 13S);
2. Connect to the charger (continuous > 2S)
CARBEST | LiFePO4 Battery | 81451 / 81452 / 81453
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CARBEST | LiFePO4 Battery | 81451 / 81452 / 81453
• Short Circuit Protection
The BMS has a built-in short circuit protection function. If the short circuit protection is tripped,
the BMS will shut the battery down and will remain disconnected until you:
1. Remove the load (for > 13 s) or
2. Connect to the charger (for > 13 s)
• High Temperature Charging and Discharging Protection
The BMS will not allow a charging or discharging current if the internal temperature of the battery
has reached 50 °C/65 °C.
• Low Temperature Charging and Discharging Protection
The BMS will not allow a charging below 0°C as it will damage the cell (unless it has the heating
function). The recovery temperature is around 5 °C. If the internal temperature of the battery has
reached -20°C, the BMS will shut the battery down, recovery temperature is around -15 °C.
• Balancing of Cells
A passive balancing process is activated by the BMS at the top of each charge cycle when
the battery cell voltage reached 3.4V and the max. cell voltage difference exceeds 50mV. This
ensures that all the cells remain at the same state of charge, which helps the longevity and
performance of the battery pack.

4.3 SLEEP MODE

1. When the BMS detects that there is no charge or discharge activity (charge or discharge
current < 1A) for 24 hours, it will automatically enter into sleep mode to save energy.
2. When the BMS detects that any single cell voltage is lower than 2.5V or battery voltage is lower
than 10V for 3 minutes, it will automatically enter into sleep mode.
If the battery enters sleep mode, you can activate the battery by:
• Charging the battery (Charging current >1A), charge voltage should be 1.2V higher than battery
voltage.
• Connecting the battery to load (Discharging current >1A), load resistance should be lower than
5KΩ.

4.4 HEATING FUNCTION FOR LOW TEMPERATURE CHARGING

The batteries 81452 and 81453 have an integrated heating function, which allows charging the
battery at low temperatures.
The internal battery management system (BMS) continuously monitors the ambient temperature
of the battery and controls the integrated heating function fully automatically. If a temperature ≤
0°C is measured during the charging process, the BMS immediately stops the battery charging
and simultaneously activates the heating function of the battery. After reaching +5°C, the
charging process is automatically continued. If the temperature rises above 10°C, the heating
function is deactivated again.

5. INSTALLATION

5.1 LI-BATTERY CONNECT APP (AVAILABLE FOR BATTERY 81452 AND 81453)

If the battery is equipped with Bluetooth function, you can use this to communicate with the
Carbest Li-Battery Connect App. The App is used for reading out battery information for real time
monitoring, receiving alarms and to update firmware.
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