How do I wired a 7.2V fan to 14.8V 4s Lipo

[ptt81]

I was wondering if I could hook up some resistors and lower the voltage to around 9v? could the resistors handle the constant load of the fan, its only 0.16A. I don't want to run it thru the external bec since its only 6v, not enough airflow

[BrianG]

Using resistors is possible, but it would be much better to use a voltage regulator. The LM317T is an adjustable unit which can be hardwired for whatever voltage you want from 1.25v up to about 1v less than the supply voltage. There are diagrams, pinouts, and formulas on the back of the package if you get it from radioshack.

[ptt81]

Ok thanks. It's just that I got a bag full of resistors in most value, rather than driving out to RS and get something else I thougth I could use them instead, its simple for wiring too. just wondering if it it can handle it without blowing the fan

[BrianG]

You can, but you are essentially asking how to build a voltage divider. And to do that, you need to know what amperage the fan draws at the voltage you want to run. There are fomulas, but it'll take a bit of math to calculate.

[maxxdude1234]

why not put 2 fans in series? twice the airflow, and the same power usage as 1 fan and an equal resistance resistor in series.... just a thought for you!

[bdebde]

Or run it full voltage till it dies.