How To Charge Lifepo4 Battery Properly

The general wisdom is that BMS lithium batteries are "thrown" and the common myth is to equalize the charge of these cells to ensure they are all filled at the same voltage.

This represents a tremendous opportunity to develop and sell electronic devices for this purpose with high profits. An industry is born to provide it. Unfortunately, most of these designs are only a little effective and many are actually dangerous.

After years of real use of cars equipped with LiFePo4 cells like 24v lifepo4 battery and 48v lifepo4 battery, it became necessary to take a very different approach to these cells and maintain them for several years and kilometers. It's very efficient without having to spend a lot of money on an expensive and complicated battery control system (BMS), which turns your car into a spaghetti thread nightmare.

The basic rule is not to throw away these cells excessively and not overload them. Obeying these two precepts assures you of years of loyal service. If you miss this, only once, it will definitely result in cell destruction and loss and eventually the loss of your package capacity early. But achieving that requires a little strategy.

Cells are not balanced by the condition of the load. And the process of balancing from above doesn't balance anything. The charging process for LiFePo4 cells consists of charging at a fixed current until a certain voltage is reached, then keeping this voltage until the intensity decreases to a certain minimum value. This is called the Constant Flow load curve (CF or Constant Flow) / Constant Voltage (Constant Voltage).

The actual voltage on the rest of the cell (open circuit or open circuit voltage) is nominal at 3.38v and can be measured only a few hours after the charging procedure. CF / CV load is a procedure, which is a recipe which, if followed carefully, will give a fully charged cell. The main recipe is:

1. Charge with a fixed intensity until the cell voltage reaches 3.60v;
2. Keep this voltage accurate up to 3.60v by reducing the intensity as needed; because cells get energy, the voltage will increase naturally. The intensity must be reduced if the voltage remains at 3.60v;
3. When the intensity reaches 0.05C, end the load.

After several hours, the voltage between 3.35v and 3.38v must be measured between the cell terminals. That is cell voltage. 3.65v is a procedural measure, not cell voltage.

So, for cell 180Ah, you have to charge at 90A to 3.60v and complete the charge when the intensity drops to 9A.

For most of us, this procedure is not possible. Our chargers can reach 15 or 20 amperes. But this procedure is quite flexible. We used this procedure up to 3.50v and it was a big success too. Given the low intensity we can get, the charge curve is so vertical that very little energy is actually added in the cell between 3.50v and 3.60v. Thus, a little autonomy is lost. But many problems are avoided. Want to know more? You can get more information from other sites that talk about lifepo4 battery.