Lithium batteries, like any other batteries, have a specific discharge curve. That means that the voltage of the LiFePO4 battery decreases with the decrease in battery capacity (from 100% to 0%). The specific battery voltage state of charge (SOC) is determined by voltage charts. To help you out, we have prepared these 4 lithium voltage charts:
- 12V Lithium Battery Voltage Chart (1st Chart). Here we see that the 12V LiFePO4 battery state of charge ranges between 14.4V (100% charging charge) and 10.0V (0% charge).
- 24V Lithium Battery Voltage Chart (2nd Chart). Here we see that the 24V LiFePO4 battery state of charge ranges between 28.8V (100% charging charge) and 20.0V (0% charge).
- 48V Lithium Battery Voltage Chart (3rd Chart). Here we see that the 48V LiFePO4 battery state of charge ranges between 57.6V (100% charging charge) and 140.9V (0% charge).
- 3.2V Lithium Battery Voltage Chart (4th Chart). This is your average rechargeable battery from bigger remote controls (for TV, for example). Here we see that the 3.2V LiFePO4 battery state of charge ranges between 3.65V (100% charging charge) and 2.5V (0% charge).
Lithium battery state of charge charts are a reflection of the results we get with Peukert’s law. This battery capacity law is an approximation of the capacity of lithium batteries at different rates of change and looks like this:
Cbattery = Ik × t
Since we have LiFePO4 batteries with different voltages (12V, 24V, 48V, 3.2V), we have prepared all 4 battery voltage charts and, in addition, LiFePO4 or lipo discharge curves that illustrates visually the reduction in voltage at lower battery capacities.
Let’s start with a 12V lithium battery voltage charge, and go one-by-one to 24V, 48V, and 3.2V lipo batteries voltage charts:
12V Lithium Battery Voltage Chart (12V LiFePO4)
|12V LiFePO4 Lithium Battery Voltage:||Battery Capacity (Percentage):|
Notice that at 100% capacity, 12V lithium batteries can have 2 different voltages; depending if the battery is still charging (14.4V) or if it is resting or not-charging (13.6V).
What is interesting to see is that a 12V lithium battery has an actual 12V voltage at only 9% capacity.
Here is the 12V lithium battery discharge curve:
You can see that the electric voltage at 0% is still 10.0V.
Here is a similar chart for 24V lithium batteries:
24V Lithium Battery Voltage Chart (24V LiFePO4)
|24V LiFePO4 Lithium Battery Voltage:||Battery Capacity (Percentage):|
As you can see from this 24V lithium battery state of charge chart, the relative relationship between voltage and battery capacity is the same as for a 12V battery. It’s just that a 24V battery has a 100% higher voltage. The 24V actual voltage in this case is also measured at 9% capacity.
Here is the 24V lithium battery discharge curve:
We see that the slope of the line is the same as for 12V lithium batteries. In fact, all lithium batteries have this kind of slope, since they function on the same underlying technology.
48V Lithium Battery Voltage Chart (12V LiFePO4)
|48V LiFePO4 Lithium Battery Voltage:||Battery Capacity (Percentage):|
You can see that 48V lithium battery voltage ranges quite a lot; from 57.6V at 100% charge to 40.9V charge. The 48V voltage is measured at 9% charge, the same as with 12V and 24V lithium batteries.
Here is the 48V lithium discharge voltage graph that illustrates these voltages visually:
3.2V Lithium Battery Voltage Chart (12V LiFePO4)
3.2V lithium batteries are those regular batteries you put in older TV remote controls.
Here are the voltage discharges:
|3.2V LiFePO4 Lithium Battery Voltage:||Battery Capacity (Percentage):|
As you can see, 3.2V LiFePO4 battery can output anywhere from 3.65V (at 100% charging) to 2.5V (0%).
Here is the 3.2V lithium battery discharge graph:
With these 4 lithium battery voltage charts, you are now fully equipped to figure out the voltage of 12V, 24V, 48V, and 3.2V batteries at different charges.