Battery purchase  (2)

GOLDBAT 4500mAh 22.2V 6S 50C LiPo RC Battery Pack with XT60 Connector for X Class Drone Racin

●Chemistry: Lithium polymer
●Configuration: 6S1P
●Voltage: 22.2V
●Capacity: 4500mAh
●Discharge: 50C
●Net Weight: 605g
●Length(dev.5mm): 137mm
●Width(dev.2mm): 43mm
●Height(dev.2mm): 50mm
●Connector Type: XT60 Plug
●Wire Gauge: AWG10#
●Balancer Connector Type: JST-XHR

Chalk Board.   (collected information as basis for decisions) 

                                                               Battery selection and power management        

(1) need to establish battery management system
         (Recommended -- http://www.mauch-electronic.com/  158)

Battery Notes 
C Ratings

• A C rating is simply a multiple of the stated capacity of any battery type.
• A C rating is relevant (and differs) for both charge and discharge rates.
  • For example, a 2000 mAh battery (irrespective of voltage) with a 10C discharge rate can safely and continuously discharge 20 amps of current (2000/1000=2Ah x 10C = 20 amps).
• C Ratings are always given by the manufacturer (often on the outside of the battery pack). While they can actually be calculated, you need several pieces of information, and to measure the internal resistance of the cells.
• LiPo batteries will always have a higher C rating than a Li-Ion battery. This is due to chemistry type but also to the internal resistance per cell (which is due to the chemistry type) leading to higher discharge rates for LiPo batteries.
• Following manufacturer guidelines for both charge and discharge C ratings is very important for the health of your battery and to operate your vehicle safely (i.e. reduce fires, “puffing” packs and other suboptimal states during charging and discharging).

Energy Density

• Energy density is how much energy is able to be stored relative to battery weight. It is generally measured and compared in Watt Hour per Kilogram (Wh/Kg).
  • Watt-hours are simply calculated by taking the nominal (i.e. not the fully charged voltage) multiplied by the capacity, e.g. 3.7v X 5 Ah = 18.5Wh. If you had a 3 cell battery pack your pack would be 18.5Wh X 3 = 55 Wh of stored energy.
• When you take battery weight into account you calculate energy density by taking the watt-hours and dividing them by weight.
  • E.g. 55 Wh divided by (battery weight in grams divided by 1000). Assuming this battery weighed 300 grams then 55/(300/1000)=185 Wh/Kg.
• This number 185 Wh/Kg would be on the very high-end for a LiPo battery. A Li-Ion battery on the other hand can reach 260 Wh/Kg, meaning per kilogram of battery onboard you can carry 75 more watt-hours.
  • If you know how many watts your vehicle takes to fly (which a battery current module can show you), you can equate this increased storage at no additional weight into increased flight time.

https://diydrones.com/profiles/blogs/how-to-guide-pixhawk-with-6s-batteries-4s