In the last article, which was part 1 of our set out to find which battery (2S or 3S) will last longer in FrSky Taranis X9D Plus SE. We concluded the last article by defining and understanding some terms related to batteries and electronics. So it is time to find out if a 3S battery will give more backup time, so let's find it out.

 

Does 3S give more back up than 2S battery for FrSky Taranis X9D Plus SE?

               Yes, a 3S battery will give you more back up time than a 2S battery does. How does that work? Let again come back to the case of Qx7 and assume you have a 2s and 3s 2000mAh battery. As I have said, the power is constant for a system. We know that the power of Qx7 is 1.44W ( 9v x 0.16 = 1.44W) and it has to remain constant.

               However, the batteries we are considering is 2S and 3S. So let calculate the current consumption at 7.2v and 11.1v (Nominal voltage of Li-po is 3.7v).  So if qx7 is operated at 7.2v, then the current consumption will be 200mAh (1.44/7.2= 0.2A) which is more than the current consumption at 9v.  Don’t get confused why it draws more current at a lower voltage, It has to be more, as I have to recall that the current consumption will be high when voltage will be low. Then only power will remain constant.

               Let's calculate the current consumption for the 3s 2000Mah battery, which will be around 129mAh (1.44/11.1=  ~0.129A). Now you know the reason why it is lower than the current consumption at 9v. Now we have the current consumption at 7.2v and 11.1v which are the nominal voltage of the 2S and 3S battery.

  

               So let's calculate the Backup time for both batteries. We need to calculate the watt that each battery can pump in an hour. For the 2S 2000Mah battery, it will be 14.4 watt-hours (7.2v x 2A = 14.4 watts per hour). Similarly, for the 3S 3000mAh battery, it will make 22.2 (11.1v x 2A = 22.2 watts per hour watt-hour)  for 1 hour.

               So let's calculate the run time for these batteries to understand the difference. For the 2000mAh 2S battery, the run time will be 10 hours ( 14.4/1.44 = 10 hours). For the 2000mAh 3S battery, the run time will be 15.41 hours ( 22.2/1.44 = 15.41 hours)  which got a huge difference than using a 2S battery. You can get 5.4 hours of extra run time with a 3S battery than a 2S battery with same

               Now you have understood the benefit of using a 3S battery over 2S battery in your FrSky Taranis X9D Plus SE. Before jumping to the conclusion 3S battery is the best for Taranis X9D Plus just because it can provide more back up time, then we need to consider some other important facts as well.  

 

Why not go for a 3S battery?

               First of all, we need to understand the important point not all the Taranis support 3S voltage input. Only the FrSky Taranis X9D Plus SE, X9D Plus, X9D supports 3S Input voltage.  The operating voltage range is 6-15v to be in specific. So you might ask which FrSky 9XD Plus doesn’t support 3S input. Yes, good question!

               The latest FrSky X9D Plus 2019 and X9D Plus SE 2019 versions don’t support 3S voltage input. The operating voltage range is 6.5-8.4v if you are wondering about the supported voltage range for these radios.

Moreover,  FrSky Taranis X9D Plus SE, X9D, and X9d are all discontinued when the 2019 versions were released.

               So do not opt for a 3S battery if you are having the latest version of X9D plus. Some people believe that connecting the receiver to the radio for flashing firmware will fry the receiver if the battery on the transmitter is a 3S. But that is a misconception because the voltage rail on the JST pins for flashing firmware to the receiver is 5V.

 

Conclusion

               We have briefly covered how significant is the difference in the backup time in using a 2S and 3S battery on Frsky Taranis X9D Plus SE. Please keep in mind that the latest Taranis X9D Plus 2019 or SE 2019 doesn’t support 3S voltage and it will fry the voltage regulator in the internal motherboard. So don not make that mistake. I hope this article has helped someone to learn new things about batteries in general. Thanks for reading it out.