Lithium-ion batteries have a very wide application range. They can power up small electronic devices such as smart watches to larger electric vehicles. Due to its varied range of applications, they come in different packaging and in such battery packs,

even when individual cell voltage exceeds by a few milli-volts above 4.2 V, it may result in thermal runaway and explode the cell. During discharge cycle, cell imbalances hinder the use of battery to its full capacity. This in turn decreases the battery lifetime.

The individual battery cells should be equalized on a regular basis to keep the imbalances to a minimum and to have a good battery life. The process of balancing the individual cell charges by measuring the cell state of charge (SoC) and its voltage in a battery pack is known as cell balancing.

 

This paper details an active cell balancing technique that uses a buck converter for balancing a series connected battery pack of lithium-ion cells. A buck converter along with a pair of MOSFET switches for each cell,

one turned on for charging the cell and the other one turned on while discharging the cell is used in this experiment. An algorithmic model suitable for reconfigurable battery systems that measures the individual cell voltages and is developed for balancing a pack of series connected Li-ion battery cells.

The developed model is simulated using MATLAB for verifying its performance. A state of charge of 25% is maintained across the cells and when SoC value drops below this even a difference of 0.02% is sensed by the algorithm to initiate balancing function.

This balancing is found to take 275 ms to balance three 3.7 V batteries and thus the model is found to respond faster. The results show that this method can self-adaptively attain satisfactory performance within a limited equalizing period.

 

 

Technical Parameters

 

EnerKey BMS Active Balancer 5A 3S 4S 5S 6S 7S 8S 14S 16S 18S 19S 20S 21S LFP LTO LI-ION lifepo4 Balancer Capacitor Balancer
Product model	EK-C16S5A	EK-C17S5A	EK-C21S5A
Product strings	16S	17S	21S
Suitable strings	12-16S	13-17S	17-21S
Product Size(mm)	L125*W91*T16	L115*W102.5*T16	L145*W130*T18
Weight with box	0.32kg	0.33kg	0.39kg
Battery Type	NCM/LFP/LTO	NCM/LFP/LTO	NCM/LFP/LTO
Suitable capacity	30ah-300ah
Voltage equalization accuracy	5mV (typical value)
Balanced Cascading	Support balanced cascading for battery packs, for example , it can cascade for 11S , 24S ,36S , 48S....and so on
Single cell voltage collection range	NCM/LFP version : 2.7V-4.2V
	LTO version : 1.8-4.2V
Undervoltage protects sleep voltage	NCM/LFP version＜2.7V
	LTO version＜1.8V
Under voltage protection Start balancing voltage	NCM/LFP version: 2.835V
	LTO version: 1.89V
Equilibrium method	Patented (Patent No.: ZL 2019 1 1259513.3) balanced architecture Fit capacitor method, the entire battery pack is balanced at the same time. Connect to the battery pack for automatic balancing (default). You can add a switch to manually turn on or off balancing.
Equilibrium current	0.1V Differential pressure 1A Balanced current,
	the differential pressure is proportional to the balanced current,
	the maximum allowable operating current is 5.5A
External power supply	No need for an external power supply,
	relying on the internal energy transfer of the battery to achieve sdjacent equalization.
Quiescent operating current	7mA, the total string draws power
Sleep standby current	0.1mA(typical value)
Operating Temperature	-20℃ ~ +60℃

 

 

Packing List

 

 Wire connect

A single EK-C16S5A supports the use of 12 and 13 and 14 and 15 and 16 string battery packs. The wiring method is as follows:

 

EK-C16S5A supports cascading battery packs. Fox exmple, 2pcs of 16s cascade to 31s, see below drawing:

NOTE:As shown in the figure above,there can be multiple common ends of energy exchangeso that the efficiency of equilibrium will be higher;It is also possible to use only one common end of theenergy exchange atthejunction of two modules.

The other free feet are suspended, and it is best todistribute the number of strings equally on each board.If you need the cascade diagram for more strings, Please contact our online service, Thanks.

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*Please look the battery body, If the normal voltage of your battery shows 3.2V, The battery is LiFePo4.

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