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Current-Logic.com now provides a series of Balancing Board for Li-Fepo4 Battery Packs or Li-CO2/Li-MnO2/Li-NiCoMn based battery packs, and full Li-Ion battery management system (BMS) that include active balancing as well as temperature monitoring, charging, and other features to maximize the life of a battery pack.

Battery balancing and battery redistribution can maximize a battery's capacity to make better use of its energy available and increase the battery's lifetime. It is also called battery balancer or battery regulator. Balancers are often found in Lithium ion battery packs for cell phones and laptop computers, and electric vehicle battery packs. Generally every Lithium ion battery packs should have balancer for safety and effeciency reasons.

Usually, different cells in a battery pack may be at different levels of state of charge (SOC). Without redistribution, the cell with the lowest capacity will go empty sooner, and the whole battery pack will stop outputing(even though other cells are still not empty); this limits the energy that can be taken from the battery.

Without balancing, the cell of smallest capacity can be easily overcharged or over-discharged while cells with higher capacity undergo only partial cycle. For the higher capacity cells to go full charge/discharge cycle of the largest amplitude, balancer should “protect” the weaker cells; so that in a balanced battery, the cells with the largest capacity can be fully filled and will not overcharg any other weaker/smaller cell, and they can power out without over-discharging any other weaker/smaller cell. Battery balancing is done by transferring energy from or to individual cells, until the SOC of the cell with the lowest capacity is equal to the battery's SOC.

 
battery management system
battery balancer

603FV1
This spec is an example of balancing board for a battery pack contains 6 polymer lithium ion batteries (rated 4.2V) in series. We also have balancing board for battery packs with 3-17 cells (common types like 3.6V, 3.7V, 4.2 etc) in series connection

The upper one is sealed with metal shield, which provide extra protection and heatsink for the balancing board

The lower one shows the inside structure. Each battery cell is monitored/protected by complete circuit.

The high lighted fields are the key parameters when choosing a battery balancer.

Because now most battery cells are made to a standard, in most cases, to choose a battery protector, user only need to know how many cells are in the battery pack, and what is the cell type.

Usually user can pick a protector by "My battery pack is using xx cells of xxV in series"

 

Details

Min. Typ. Max Error Unit
Battery Gas Polymer
Battery Links 6S/1P

Absolute Maximum Rating

Input Charging Voltage 25.2 ±1% V
Input Charging Current 2 5 A
Output Discharging Voltage 2.50 4.20 V
Output Discharging Current

5

10

Continuous Output Discharging Current 10 A

Ambient Condition

Operating Temperature -10 65
Humidity (No Water-Drop) RH

Storage

Temperature -40 75
Humidity (No Water-Drop) RH

Protection Parameters (for Individual Cell).

Over-Charge Voltage Protection (OVP) 4.175 4.250 4.275 V
Over-Charge Voltage Protection Release (OVPR) 4.180 4.190 4.200 V
Over-Discharge Voltage Protection (UVP) 2.550 2.500 2.450 V
Over-Discharge Voltage Protection Release (UVPR) 2.950 3.000 3.050 V
Over-Current Charge Protection (OCCP)

None (this is duplicated with SC protection, can be set to customer's requirements)

A
Over-Current Discharge Protection (OCDP) 35 40 48 A
Over-Current Protection Delay Time(OCPDT) 10 20 40 mS
Over-Current Discharge Protection Release
Short circuit current protection 180 200 250 A
Short circuit current protection delay time 200 250 350 uS
Short circuit protection Release Cut off Load
Charging and Discharging Temperature
Charging and Discharging Temperature Protection Release
Balance Temperature
Balance Temperature Protection Release
Cell balance
BleedStartPoint 4175 mV
BleedAccuracy 10 mV
BleedCurrent 45 55 60 mA
Balance Mode Charging

Current Consumption

Normal Mode uA
Idle mode 100 uA
Sleep mode uA