1. I have a 24V 4AH battery. How much capacity can I operate the PTC heater with this battery?
-I want to use 24V 200W PTC as a priority.
2. How long can the applicable PTC heater be used without battery charging?
3. Please tell me how to calculate additional usage time.
1. The battery capacity is determined by you according to how much you plan to use continuously after charging once.
24V x 4Ah = 96Wh is the amount of power the battery has. If you connect a PTC heater with 200W power consumption here,
96Wh/200W = 0.48h It can be used for about 30 minutes. That is also theoretical, and in reality, the battery capacity decreases as the current consumption increases, so the actual usage time seems to be less than 20 minutes. And in case of lead acid battery, the voltage per cell should not drop below 1.8V. Then, it cannot be charged any more. If it is a 24V lead acid battery, stop using it and charge it when it reaches 21,6V or less.
2. As calculated above, the battery power capacity = voltage x current capacity. In the above case, it becomes 24V x 4Ah = 96Wh, and the usage time is obtained by dividing the power consumption of the PTC heater.
3. However, the above calculation formula is theoretical, and in reality, it takes less time than the theoretical calculation.
In lead acid battery, 4Ah is expressed based on 1/20C discharge rate (about 0.2A). If it exceeds 0.2A, the battery capacity decreases.