series/parallel Li-Ion battery string - capacity imbalance

Li-Ion battteries age differently - the differences often aggravated by common charging and protection regimes.

Battery cell voltage ballancing circuitry is quite limited in it's current handling capacity - commonly rated in 10s of milliamps, applied sometimes only during charging may have difficulty allowing even for differences in self- discharge rates of aging batteries, which may be composed of many parallel cells.

Might it not be useful to redistribute aging cells so that parallel batteries in a string are composed of an equal mix of capacities?

This would, at least, prevent one undercapacity parallel battery in the series string being repeatedly overcharged, or being repeatedly responsible for protective cut-off during discharge.

This would allow re-use of end-of-service life cells.on-site, within the same packaging, reducing disposal or recycling/shipping issues.

Thoughts?

AFAIK when charging cells in series, a parallel voltage limiting circuit is often used on each cell. Or just give each cell its own isolated charging electronics. In the case of discharge of series connected cells your options are limited, if one fails open no output, if one is short too low output. If cells are really that bad, away with those. Using cells of one batch helps.

All that said, I still have to see the first cell fail.

You could give each cell its own power converter...and add those outputs. I have some very cheap 3.7 V to 5V lipo boards from ebay. Not much current though, more for micros.

Cost versus probabilities?

I have seen a Tesla battery pack taken apart somewhere online, quite impressive, high currents, sensing.. nice job!

series/parallel Li-Ion battery string - capacity imbalance - re-use