Blog - Winston

The information about the 48V DC power energy storage systems

18.Jul 2012
| Blog - Winston

The 48V DC systems are usually assembled using 16 LiFePO4 cells with nominal voltage of 3.2V. You can check the example of the voltage levels for such a system at these examples (2).

The 16 cells system has following voltage levels

  • Nominal voltage - 16x 3.2V = 51.2V
  • Maximal charge voltage - 16x 3.65V  < 58.4V
  • Minimal voltage under load - 16x 2.8V   > 45V

In order to maintain compatibility with the lead-acid systems, some customers prefer using only 15 cells of the LiFePO4.  The 15 cells system has these voltage levels.

  • Nominal voltage - 15x 3.2V = 48V
  • Maximal charge voltage  - 15x 3.65V  < 54.7V
  • Minimal voltage under load - 15x 2.8V   > 42V

For compatibility reasons with other products (chargers, solar chargers, etc)  it is preferred to use the 16 cell solutions.

An example of 10kWh system at 48V can be assembled using 200Ah cells.
16 cells x 3.2V x 200Ah = 10.24 kWh for energy storage

The main advantage of the lithium cells is that they provide the same real capacity both at slow discharge rates and at high-speed charge and discharge. This means that the battery banks for surge power supplies can be significantly smaller when using LFC cells in comparison to lead-acid cells.

For lead-acid cells the capacity is give as related to the discharge time. Examples: C5, C10, C20. The value for LFP (LiFePO4) cells is always the same. This means that for high-speed discharge installations, you are not loosing the precious energy.

Another advantage is the low weight of the installation. 16 pcs of the LFC cells for 10kWh battery bank weight less than 150 kg; the components for solution can easily be transported in a personal car.

Of cause, the greatest advantage is the number of cycles.  For a stationary usage with a typical cycle day/night – i.e. 1 cycle per day, the life span at 5000 cycles is 13 years. When starting using now, the cells will keep serving in 2025. Without any need to add the electrolyte and other complicated maintenance needed.

What do you think?

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