....
That's ≈78% to 81% SOH really skimming the low end for a successful battery build.
Sony has done some strange things with cell chemistry that in some cases makes a very good cell. Unfortunately they don't play well with others in the sandbox,. If you only use Sony cells and they are all the same great but I wouldn't mix and match them with anything other than themselves.
Remember INR chemistry = low IR, usually ≤ 30mΩ and more than likely with a good cell <25mΩ. Most newer high drain cells have an IR in the low 15mΩ.
So if I would make a seperate string out of the sony cells, say 14s20p or 14s40p, depending on what can be used from my other US18650V cells and use that string together with another string of mixed samsung INR-18650-22P and/or Sanyo UR18650, the strings should play nice together.
These are the number of cells I have gathered up to now:
# Cells | Capacity | Part Number and Color | Manufacture |
444 | 3141,3492 | ICR18650-22P | Samsung |
49 | 342,2916 | INR18650-20R | Samsung |
27 | 179,9604 | UR18650R | Sanyo |
142 | 948,3822 | Blue cells | unknown |
280 | to be measured | US18650V3 | Sony |
300+ | to be measured | UR18650AA | Sanyo |
200-300 | to be measured and opened form packs | US18650V | Sony |
The ones with capacity meantioned are all tested with good IR (well within specified range by manufactorer)
It's because I've read a lot off confusing messages about these Sony cells, I'm trying to decide clearly what to do with them and if they are worth my time to clear them from the packs and test them all.
Is there a way to detect the chemistry of a cell ? I've got the so called Blue cells, they are cells from hooverboards and e-steps by the looks of the design from the packs I've dissassembled, but there is no serial or whatsoever on them. They all come out in this IR trend:
This is the capacity graph of the cells:
The ones at the end are the "bad ones" they were 0V or high IR before putting them in the charger, but just for statistics I added them in the sheet so I could detect and the ones with 0 are offcourse the ones that didn't even measure anything at start and were binned. This batch I acted differently. Pre-measure each parallel pack (0V => keep to end), open up, numbered all cells, measure IR, good IR => into charger, bad IR => bin. End processing : try reviving the 0V cells with low charge for 10 minutes. Rest, and repeat until they are recognized as Li-ion. some were recovered, some will be binned. Strangely enough, some high IR cells are also the ones with the highest capacity. They all "rested" the same amount of time (3 weeks) before being tested