as stated above, i am wondering how to know how much charging energy a portable charger can hold
for example, we can have 1 product with 5000maH with 2 batteries but another product with 13000maH with 4 batteries.
does the amount of hours a portable charger can hold depend on maH or the amount of batteries?
2 batteries to 4 batteries meaning that product with 4 batteries has exactly double the storage inside or 2.6x (looking at maH)
hopefully my question makes sense, thank you all
@throwaway9435 mAh determines the amount of energy. the number of cells or batteries has nothing to do with it.
A 5000 mAh battery can output 5000 milliamps for one hour or 1000 mA for 5 hours or 500 mA for 10 hours, etc, etc
Example:
If your phone charges at 2.0 Amps (2000 mA) using the above 5000 mAh battery bank the bank would be depleted in approx 2.5 hours. If your phone has say a 2500 mA battery you should expect 2 charges from flat to full with the same 5000 mAh battery pack. Get a 10000 and double your capacity
Hope this helps. Cheers 
Energy is Volts x Amps x hours. Volts x Amps = Watts. So energy is Wh.
Energy is not mAh.
However as the cells are similar voltages, using mAh is a rough approximation to energy.
If you can see a Wh figure then that is actual energy.
Yes, that is correct @nigelhealy watts are energy. Thanks for clarifying to keep the answer real.
I just wanted to keep it simple based on the question asked and I was assuming the voltage was constant and not doubling when going from 2 batteries to 4 batteries.
The possible length of the technical answer could not be given without adding a lot of confusion as watts are often omitted from smaller consumables.