Quick update:
Started some tests yesterday and after few hours figured out had some settings left in from previous charging/discharging so had to run things again.
But it ain't all bad, before I went to bed I've put one discharged pack charging and today when I went to work it was still charging after almost 8 hours and number was looking good -
5000+ mAh

Will see final number when I get home, then start discharge test and then I also plan to do 80% charge test - to se how long it takes from empty to 80%.
@xchristheisx depends on how high speaker protrudes. If it isn't higher than those bottom AA battery spacers it could work.
Don't grow up.
It's a trap.