Li-ion battery selection

[ZeroResistance]

I am looking at Li-ion battery chemistries that would be suitable for inductive / motor loads. Basically my loads are bldc motors and the total wattage would be around 30 watts.

From http://batteryuniversity.com/learn/article/types_of_lithium_ion I see that NMC battery seems to be well suited for this is has good energy density, specific power, safety cost performance and lifetime.

The Lithium Iron Phosphate(LiFePO4) battery also looks interesting although its energy density is low compared to the other Li-ion chemistries but it is highly safe.

A search on amazon revealed that Panasonic is a reputed and reliable source of these batteries and they generally go in the 18650 form factor however the battery chemistry is stated as NCR, any idea how NCR compares to the NMC battery?

I'm open for Any other suggestions for battery chemistry to power the loads I stated earlier.

[chota.sanjiv]

https://batterybro.com/blogs/18650-wholesale-battery-reviews/18880255-battery-chemistry-finally-explained

[ZeroResistance]

https://batterybro.com/blogs/18650-wholesale-battery-reviews/18880255-battery-chemistry-finally-explained

That's some excellent info. Many thanks!!!
I would like to keep the  batteries as a backup source so during mains operating they would be either in charging or standby mode.
My next question is my loads are rated for 12V, although I thing bldc motors can work over a wide range of voltage correct me if I'm wrong.
So lets say if the nominal voltage of the battery is 3.7V and I charge it to a max of 4.2V and if I use 3 cells that makes it 4.2 x 3 = 12.6 volt max and lets say that I can use it upto a min of 3V per cell so that makes it a min of 9V. So the battery voltage would vary from 12.6 to 9V.
for 4 cells the battery voltage would be from 16.8 to 12V.
So should I use the 3S configuration or the 4S?