How efficient is the serial connection (in recharging) of the powerbank?

Question

Electronics

Will a serial connection of several power banks be effective in increasing the total capacity?
How realistic (by how many times) will the capacity increase in a battery of N identical products?

Answer 1

If the efficiency is 90% (for input and output), then 3 power banks of 10A * h according to this scheme will give:

3й - 10000*0,9 =9000 (разряд 3го)
2й - 10000*0,9*0,9*0,9 = 7290 (разряд 2го, заряд 3го, разряд 3го)
1й - 10000*0,9*0,9*0,9*0,9*0,9 = 5904,9 (разряд 1го, заряд 2го, разряд 2го, заряд 3го, разряд 3го)

Total 22195mAh or 74% of usable capacity.
Here is the calculation table

Answer 2

So-so idea, because each output from the bank is equipped with a DC-DC converter, which will eat up to itself, within its efficiency, from 7 to 15% of the energy.
And in the charging circuit, a linear stabilizer can generally stand, which has no efficiency as such - it will conscientiously transfer all the "extra" energy into heat.
And if there is an "empty" bank in the middle of the chain, it will generally be a profanity - it takes more energy to charge an empty battery than it can then give back.

Answer 3

If you need to extend the uninterrupted time of work, and there are several weak power banks, then you can do this. This makes sense if there is no one to poke jars or you cannot interrupt the process.
But as mentioned above, this is not very reasonable in terms of efficiency. In terms of efficiency, it is more reasonable to connect them in turn, discharging each completely.

Answer 4

The increase in capacity is achieved by connecting the batteries in parallel.
When connected in series, a huge amount of energy will be spent on charging the next battery, losing a lot of energy to heat. So inefficient that it is better to forget about such an idea right away