EDF CELL COUNT – ELECTRIC DUCTED FAN
Each fan combination may support a couple different cell counts. It is important to determine the cell count in order to target specific power and weight goals. Not only are the Cell counts important, but the capacity in mAh is as well.
EDF Cell count
Cell counts will typically follow a range. Here is a quick and general list for common EDF sizes showing cell counts and capacities in mAh. Some setups may fall outside this general range.
| Fan Size | LiPo Cells (series) | Capacity (mAh) |
|---|---|---|
| 56mm | 3s | 1500 |
| 70mm | 3-6s | 2200-4000 |
| 80mm | 4-6s | 3700-5000 |
| 90mm | 6-10s | 3700-5000 |
| 120mm | 10+s | 5000+ |
Advantages to higher cell counts and Capacities
There are advantages to higher cell counts and capacities. First we will look at the more obvious disadvantages. As you increase the cell count or capacity, weight of the plane increases as well as wing loading. Many people agree that a lighter plane is a better flying plane. Not only does weight increase but the physical size of the packs will need a large area inside the plane. Make sure you can still achieve proper center of gravity with larger/heavier packs.
The natural advantage of running more cells in series or increasing the capacity, is the ability to provide more power to the motor. A higher cell count will increase voltage. A larger capacity generally increases the amount of current you may pull from a given system. Keep in mind that your motor ultimately determines how much power is consumed. Not how large the pack is or how many amps of current you can safely discharge continuously.
If your flight times are running a bit short and you have some weight to spare, increasing the battery capacity will provide you with more run time.
Using voltage to reduce Load
In electric ducted fan jets, the power system is often very hard on the battery packs. Electric ducted fan models need a lot more continuous power to stay in the air and they draw a lot of it. One way to reduce the amount of stress on your battery packs is to increase voltage. Increasing voltage and properly selecting a motor can in fact reduce the amount of current and maintain the same amount of wattage. This will be at the expense of weight.
Determining the optimal power to weight ratio trade off to meet your goals is the largest accomplishment in determining which cell count and capacity to use. Always purchase the largest “C” value for LiPo cells as your budget allows. The higher the better, always!