an amazing fact about bosch blue 10.8/12v batteries

[big-all]

first point to clarify and get it out the way 10.8/12v are the same they are all made from the same 3.6v cells but voltage taken after charging when batteries are around 20% over volt because off charging
now its not a scientific study but the timings are within 5 mins using a 330lumins work light as a constant source
i measure all my batteries in turn charged on the same charger and tested within about 5 day and recorded the run time battery amps capacity the batteries go from 2007 to 2017 so 5 to 15 years old
i always used to bang on about nicads an nmh batteries on cheap tools loosing perhaps 20 to 25 % capacity a year with decent makes being perhaps 5-15% a year now i know lions are better but was stunned at the results
i have 15 batteries [i know mental and stupid ??]
7x 1.3ah 07-12 lowest was the newest battery at 3h3m with the oldest 3.13 average 3.20mins so overall no appreciable loss off capacity over 5 years
the 5 x2ah went from 13-17 and 5.46 to6 .05m with the age being slightly more reliant but still a minute difference
the 2x2.5 2015 where the one failure one giving an expected 7.h 19m and the other 4.40m
the one 4ah gave the best results per ah at 12h 26 mins but pretty much in line with the best 2ah 1 year later at 6.05 and 6.02
now the reason i have so many batteries is we assume 5 years old equals near to dead so new full tool with batteries makes sense but never took the time to check just made assumptions
now for most this will be a fully pointless thread but for others like me who like to mull over information its both fascinating and surprising
i would further add because i am not heavy trade in early years to mostly retired for the last 10 years with more batteries than a wartime costal defence it will skew the average overall but the capacities being so close over batteries at least 5 years old up to 15 years old is quite amazing

and just to check i will try battery 12 on the same charger and another in case the fault is not with the battery