How to choose LiFePo4 battery? What parameters should be paid attention to when you purchasing batteries?

How to choose LiFePo4 battery? What parameters should be paid attention to when you purchasing batteries?

#Battery Voltage

The nominal voltage of a single LiFePO4 cell is 3.2V, therefore most 12V battery packs, are actually rated at 12.8V. It is compatible with most chargers, controllers, and inverters.

What do you need to know is the difference in voltage between 12V LiFePO4 and 12V lead-acid batteries, to avoid the possibility of non-compatibility with other components.

A single LiFePO4 cell ranges from 2.50V to 3.65V, a 12V pack of 4 cells in series is 10.0V-14.6V, and a 24V pack of 8 cells in series is 20.0V to 29.2V.

Besides, most of the 48V battery packs in the market now are 16S solution. The actual nominal voltage is 51.2V and the voltage range is 40.0V to 58.4V. While some brands are doing 15S solution, the actual nominal voltage is 48V and the operating voltage is 37.5V-54.8V.

Although now most of the devices and appliances are compatible with a wide range of voltage. However, in some specific applications, the battery voltage is still crucial to whether it can be adapted to the involved devices.


#Max Charging Current

Previously, lead-acid batteries need 8-10 hours or a whole night to charge to full. If changed to lithium batteries, usually 2 hours to charge to over 95%.

The recommended charging current is below 0.5C, and it is not recommended to charge at a too high current. High charging current will cause the battery’s internal overheat, even though the BMS has temperature protection.

If the max charging current of the battery is very low, charging speed is too slow, it is not recommended.


#Max Discharging Current

The max discharging current of most energy storage LiFePO4 batteries is 1C.

Unlike lead-acid batteries, the BMS will cut the circuit if the current is over the limit due to the BMS overload protection. The disconnection of the circuit will cause inconvenience to the user.

For example, in a home solar system. If the inverter’s max power is 5kW, then a 51.2V100Ah battery is enough and will not cause a break. If it is a 48V100Ah battery when it reaches the peak power of 5kW, the current is 105A, which is over 1C, it may trigger the current protection of the BMS and cause the battery circuit to be cut off.

Then all the lights will go out, all the appliances, including the refrigerator, the air conditioner will stop working. It is really a very bad experience.

So the battery max power must be more than the inverter max power.

Please note, it’s the maximum power, not the rated power. There are quite a few appliances that have a peak power that is much higher than the rated power.


#Cycle Life

At present, LiFePO4 batttery cell ‘s cycle life is 3500 times and after that, battery still maintain 80% capacity. The most recommended working range of SOC is 10% to 90%. Please don’t drain the battery.


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