LiFePo4 batteries are known for long cycle life and safety. Unfortunately, charging is not allowed below 0 degrees. Luckily, the company, Power Queen, provided me with 2 such batteries free of charge for my 24V island solar system. In this post we'll look at how it works and my capacity test. At the end I'll open the battery and we'll take a look.

If you would like to learn more about our experience with the Power Queen solar battery, read my full article. Otherwise, you will find a brief summary of our experience here.

After the technical data on the battery, there are short notes from my side:

The voltage ranges in the technical data are limit ranges. I recommend a final charging voltage of 13.6V and a final discharging voltage of 12V. For higher discharge currents you can also set it to 10.8V. If the battery needs to be charged quickly, the voltage can be set to 14.4V.

Capacity test

Between discharging and charging we can determine the efficiency of the lithium iron phosphate cell chemistry. For our battery cells this is an incredible 99.77%! The losses of the charger are not included.

Internal structure of the battery

The first thing I noticed was that the cells are installed horizontally. That's not bad. However, the battery should only be installed in this position in your vehicle or photovoltaic system if you do not know how the cells are integrated inside. The top of the LiFePo4 cells always have the plus and minus contact, as well as a pressure relief valve. This valve must never point downwards.

The first heating plate is hidden between the BMS and the cells. At the bottom of the cells, i.e. the battery base, is the second heating plate. So that looks good at first.

Conclusion

I am very satisfied with the capacity, the weight of around 10 kg, and the 100A charging and discharging current. The heating will still have to prove itself in winter. If there is any important information about this, I will mention it on wohnen-heimwerken.de.