Frsky 9XD Plus is undoubtedly one of the most popular and commonly purchased radio transmitters around the world. When more and more of these transmitters were floating in the world, the need to have a choice of various batteries to power them become a concern to hobbyists. Fortunately, many of the famous battery manufactures came forward and released many batteries that are specifically designed for Taranis X9d plus.

               It was good to be having a choice to choose the replacement battery from many, but at the same time, it paved the pay for confusion to get which battery out of the many batteries available. There are a bunch of different types of replacement batteries available like Li-po, Li-ion, Ni-Mh, Li-fe, etc for Taranis Radio.

               Not the great and not the least, but we have briefly covered the advantages, disadvantages, and some other aspects of various batteries like Li-Po, Li-ion, Li-fe and Ni-Mh in the last articles. That series of articles was supposed to give an insight into various kind batteries so that you can choose which is best for a specific purpose.

               Again out of these various types of batteries, another attribute which is the number of cells in the battery becomes another constraint in choosing the battery. When it comes to Li-ion, Li-fe and Li-Po batteries, 2S, and 3S batteries are available for the Taranis that will fit perfectly on the radio. So which one should you choose?

We didn’t cover that in our introduction into the battery series. But don’t worry, this article is supposed to give you an insight into the advantages and disadvantages of using a 2S and 3S battery in your Taranis. It is very important to know how factors like power consumption, number of cells, operating current affect the battery back up time. That will definitely help you to choose between 2S or 3S for FrSky 9XD Plus.

Let's understand the terms?

               Before getting started, we need to understand terms like current consumption, watt-hour, power, voltage, etc. Learning this will not only help you to understand things related to batteries but will also help you to understand many things that you came across in day to day life.

               Operating current is the current that a device will draw in order to function for a specific time interval. If you see “Rating: 9v --- 160mA” on the backside of your qx7 radio, then it means the transmitter will take 160mA current from the battery to work for one hour. Simple right? But this is only true if it gets a constant 9v and in reality, the voltage varies upon consuming the current. So, if you have a fully charged 1600Mah battery in the radio that can constantly supply 9v, then the transmitter will work for 10 hours. Now you got it right? Its pretty simple.

               Power is the rate at which work is done or the rate at which energy is consumed or produced. Hence it is constant for a device or system. For example, come back into the Qx7 which is rated 9v at 160mA. The power (p) will be 1.44Watt (power is current multiplied by voltage, 9v x 0.16 = 1.44W). However, since the power is constant, the rated current will be different for different voltages.

               Since the current is proportional to voltage, and power is constant, if any of the factor current or voltage increases, then the other one will get decreased to make the power constant. In simple words, if your qx7 is supplied with the 10v, then the current consumption will be much lower than that it requires at 9v. If you supply 8v, then-current consumption will be more than 160mA. Hence current consumption will decrease if the voltage increase and vice versa

               Watt-hour is the amount of energy that an item consumes or delivers in a given time interval, which in fact is the Power delivered or consumed with respect to time. It is calculated by multiplying voltage by current. So for a 9v 2000mAh battery, it makes 18 Watts (9v x 2A) for one hour. Let's come back to the qx7 case again, the power rated is 1.44W at 9v 160mAh consumption. So with this 9v 2000mah battery, you will get around 12 hours (18/1.44= 12.5 hours) backup assuming that qx7 will pull 1.44 watt per hour from the battery.

               This is when you assume, if the qx7 pull 1.44 watt per hour from the 2000mah 9v fully charged battery, then the battery will last for around 12.5 hours at 100% efficiency. Since 100% efficiency is not practically possible, hence there will be some energy loss and actual backup time will be much lower than the theoretical value.

               If you still didn’t get how this works, consider your qx7 has a power consumption of 1W. Assume your battery can deliver 10watt for one hour, then the qx7 can pull 1 watt from the battery for 10 hours till the battery gets fully discharged. You can get this power consumption by multiplying the current and voltage. For a 1000mAh 7.2v battery, the power will be, 1A x 7.2v = 7.2 Watt-hour. For a device like Qx7, if it has a current consumption of 160mA at 9v, then the power will be 9v x 0.16A = 1.44 watt. I hope this has helped you better now.

               Isn't it better to step out for a while to clear off the mind after all coming by this electronic terms and maths? Yes, I thought it is better to find out the answer to our curious question in the upcoming article. So clear your mind and be prepared to read the upcoming article on FrSky 9XD Plus with a fresh mind in which we will be revealing the answer to it. Stay Tuned!