There is a lot of information around on how to charge LiIon cells.There you find all about chemistry, charge current, charge voltage, lifetime....
In short: LiIon cells are very problematic when charged to a too high voltage. The voltage limit has small tolerance.
Especially to find the end of charge needs time with lowered charge current.
problem guys
the circuit charging cell too slow taking 10+ hours , need to measure the current ,
,the current control needs to be removed (the bc547 and resi 1.5E)
test setup
-3 year old 18650 (never used)
-sony 1.5AMP charger as input with this circuit (see post1)8-O
probable causes
--the cells 3year old never used , so may be 1st charge taking time
-- the current limiter is bugging the charging
--or the BD139 eating power
I felt it is better to adopt a cheap power bank than to make own circuit ...
Adoped a china 1$ PowerBank:roll: (with vry low Q cells )to house
(swapped the PBs cells) with 100% reliable new LITHIUM 18650 cells
for a test and they work nice
charged 2 cells indicating 3500mAH effective power
XPERIA Z 2300mAH phone : 1 time
SAmsung infuze 1750mAH : 68%
Pretty happy the 2 cells will charge any cell with 1500mAh TWICE !
Going to make a 4cell version now .
One issue is the highcut is not working for the adpted cheap PB