Sciencemadness Discussion Board

Li ion batteries same size but different capacities?

fusso - 30-7-2019 at 08:40

I have some LIs from 2 battery packs, they have the same cylindrical shape, diameter and length, but with wildly different capacities (0.8 & 2.6Ah). Is this possible? Are those claimed to have higher capacity actually have capacity similar to the lower ones?
(Claimed to be damaged/broken from someone else so don't ask me if they work or not)

approximately :

Sulaiman - 30-7-2019 at 09:35

If the electrodes are thin then the cell can store a lot of energy,
if the electrodes are thick then the cell can deliver higher current.

vmelkon - 30-7-2019 at 16:14

Quote: Originally posted by fusso  
I have some LIs from 2 battery packs, they have the same cylindrical shape, diameter and length, but with wildly different capacities (0.8 & 2.6Ah). Is this possible? Are those claimed to have higher capacity actually have capacity similar to the lower ones?
(Claimed to be damaged/broken from someone else so don't ask me if they work or not)


Sure. Why not.
The external package (cylindrical) might be large but it might contain a small battery.

This isn't anything new. I once bought a Ni-Cd "D" cell battery in 1992 and when I cut it open, I saw that it actually contains a slightly larger than an AA battery inside.

fusso - 30-7-2019 at 22:40

Quote: Originally posted by vmelkon  
Sure. Why not.
The external package (cylindrical) might be large but it might contain a small battery.

This isn't anything new. I once bought a Ni-Cd "D" cell battery in 1992 and when I cut it open, I saw that it actually contains a slightly larger than an AA battery inside.
No, I mean the cylindrical LIs are the 18650 type.

[Edited on 190731 by fusso]

wg48temp9 - 30-7-2019 at 22:57

As an other poster already stated, as confirmed by batterybro.com

"The two most important specs for 18650 cells are capacity measured in mAh (milliamp hours) and maximum continuous discharge measured in A (amperes). When selecting a battery type you must favor one over the other. High-capacity batteries have a low max. continuous discharge and high-amp batteries have a low capacity. Typical highest-capacity batteries in 2015 are ~3500mAh, and highest-amp batteries are 30A."

Twospoons - 31-7-2019 at 22:15

The cathode chemistry makes a big difference - it can be optimised for capacity or current delivery.
https://batteryuniversity.com/learn/article/types_of_lithium...