I'm still learning a lot about my new(ish) hobby and I want to learn about batteries.
The shop I purchased my gear from originally recommended a LIPO 2250mAh 4S 65C/130C Burst. After reading a few posts the latest batteries I've purchased are LIPO 3000mAh 4S 20C/30C.
I know the 4S is for 4 cells. The 3000mAh is how much charge they can hold, correct? And the 20C/30C is how quickly it can get rid of that charge and power things, right?
So how do I determine the power requirements of my standard DJI-450 & NAZA kit?
And lastly, when it comes to charging what should I set it to?
Hopefully those questions make sense.
The Lipo cells that we are using are rated at 3.7 volts per cell. From this, 2S is 7,4 volts, 3S is 11.1 volts, 4S is 22.2 volts and so on. This is the voltage designation of the cells that are connected in serie (voltage increase and C (capacity in Amps) remains the same.
Now the part that confuses lots of people: When an intelligent charger charges a 3.7 volts cell, it will charge it until it reads 4.2 volts. This is 0.5 volts above the designated 3.7 volts per cell. From this, a fully charged 3S Lipo battery will read 12,6 volts (3 X 4.2 volts). This represent 100% charge. So far so good? Lets' continue...
Lets' go 0.5 BELOW designated voltage per cell (3.7 - 0.5 = 3.2 volts). You can consider that the useful charge (the amount of electricity that can safely be drawn by the system) is at 0% when you reach 3.2 volts per cell. If you keep discharging beyound this point, there is a real danger to over discharge your battery and that will kill it for good. Also, the voltage drops quite rapidly below this value and you are not going to enjoy it very much...
In other words, the operating range of 1 Lipo cell is from 4.2 volts to 3.2 volts. This only represents 1 volt BUT Lipo technology and its' inherent properties will make this 1 volt drop last much longer than, say, a Nicad battery going from 4.2 volts all the way to 0 volts. This is why Lipos are so popular! A generally accepted good practice allows for long lasting Lipo batteries is to stop flying when there is 20% left per cell. In other words, you fly and burn only 80% of the power available. Of course, this is what you aim at, I have landed near 0% a few times but I always try to land at 20 ish %. Using your NAZA battery first and second alarm with the proper values will engage my first alarm at 20% (flashing red) which tells me to land ASAP. For a F450 it should be around 10.2 volts + whatever your line loss is (usually around 0.5) so 10.6 - 10.7 volts. Do experience different values in the NAZA battery first level alarm so that when you land right away after noticing a flashing red light, as you hover at the end of the flight, your electronic voltage meter say 20%. That would be the ideal set-up. Now with the props, another story...
Just make sure that you do not use 10 X 5 props on 4S batteries with the standard DJI motors. You need 8 to 9 inches prop for 4S. 10 X 4.7 and 10 X 5 are Ok with 3S batteries. One last but IMHO vital info: do not fly with DJI props. APC or Graupner are great and SAFE. Also, when not to be used in the next 2 or 3 days, the Lipos should be discharged to 60%. You intelligent charger will do all this for you. It is call a storage charge. Lipos should not be stored fully charged for extended period of time, this will reduce their lifespan.
Hoping it helps, like a famous rabbit would say: That's it folks!
