Can i use 26650 instead of 18650 battery to make a power bank?
If yes then why normaly power banks only made of 18650 cells instead of 26650?
If yes then why normaly power banks only made of 18650 cells instead of 26650?
Ya thanks for the rply.No difference in capacity just the diameter of the cells 18mm or 26mm.
Ya thanks for the rply.Capacity can vary.
The 26650 is bigger.
The other one is cheaper option for a power bank.
I would choose 26650 if I were to make one
How will the profit come also.You should ask them why.
My guess is cost reduction. Reputable companies also wants profit.
Ya thanks for the rply.
But why reputed companies dosnt use 26650 cells.it has greater power consumption capacity and power bank size can be reduced with maximum power storage.So why the big companies are using this 18650 cells instead off 26650?
Hi,
On the technical end it's mostly about energy density, and cross sectional area vs surface area.
On the financial side it's about materials cost and how many cells are sold over a certain time period.
The energy density controls the volume of the cell, the cross sectional area and surface area determine the maximum current draw for a well designed cell.
The volume of a 26650 cell is roughly 2 times the 18650.
The cross sectional area is about 2 times the 18650.
This means that theoretically the bigger cell can hold 2x more charge and discharge at a 2x higher current.
Since the bigger cell diameter is 26/18=13/9 times, the nearest equal square is a sqaure of the bigger cells with one side having 9 cells, and the smaller cells with one side having 13 cells. The capacity difference is:
162x for the bigger cells, and 169x for the smaller cells. Thus, the smaller cells take up less space by 13/18 (about 72 percent) when arranged in a perfect square leaving space for air flow that is equal to the space lost in packing circles side by side in a grid.
You'd have to look at more close packing to see if you can get an advantage that way, but then there would be less air space for cooling too which would have to be accounted for by determining the difference in cooling for both packs.
The cost factor probably plays a bigger part though. We'd have to compare equally scaled ratings which means we'd have to look up the larger cells with 2x current and 2x charge storage and compare pricing.
We'd also have to see if there is any significant self discharge issues for the larger cells vs the smaller cells.
Lithium-ion, including lithium-polymer batteries used in Power Banks and smartphones eventually lose their capacity over time (typically between 200 up to 1000 cycles depending on the battery cell quality and chemical composition) . The bigger the battery is, the less cycles will need to charge it and the longer it will last. Smartphones discharge their battery daily, thus has shorter battery lifetime than a large capacity power banks, so is it will be better to make a power bank with big battery?