How Often Legit-Brand Batteries Significantly Below Specified Capacity?

I have two Molicel P26A cells bought from reputable US vendor that I have tested a couple of times now and each time they both land between 2,300 to 2,350 mAh. Same unit (DLYFULL) showed VTC5 at 2,597 (versus 2,600) and a no-name 26350 bought from a reputable vendor was within a percent or two also.

The only cells that I have tested (maybe a dozen or so) where the capacity reading just does not make much sense are two obviously fake 30Q’s and these two Molicel.

The Molicel cells otherwise seem legit and work fine in D4V2 so it is not that big a deal, but I just wonder how often is a reputable cell this far off?

Or should 10% not be considered significant?

That depends on the discharge cutoff voltage vs. the one specified on its specs. For example HKJ uses 2.8V so many cells get ~100mA less than stated. However the HKJ’s P26A samples actually exceeded their rated capacity by a bit.

Another factor is that not all reputable US vendors are authorized Molicel distributors so they may be getting lower grade cells or old stock.

I don’t get more than 2,750mAh out of Samsung 30Q and no more than 3,250mAh out of Sanyo GA when running discharge cycle with the MC3000, I run them down to 2.5V with a cut off current of 100mA.

I would say 5-10% below rating is acceptable since their testing conditions are nowhere near real world use. It also greatly degrades the capacity when the cells are stored in fully charged state.

That’s strange.

For a new Samsung 30Q (only a few charge/recharge cycles), I can get 2900+ mAh discharging with the MC3000 (charging them to full 4.20v at 0.1A terminating current; then discharging at 0.5A cut-off 2.50v)
For Sanyo GA, I usually get around 3350-3400+ mAh using the same test parameters (charge to 4.20v end charge current of 0.1A; then discharging at 0.5A cut-off 2.50v) Assuming new batteries.

I have some pretty-used 30Q which now register only around 2600-2700+ mAh when doing the same test parameters on my MC3000.