Based on LION and LFP battery datasheets the charging voltage must be compensated by temperature, especially in cold conditions like -25 Celsius.

I am looking for charging IC or even simple module to charge 3..4 cells in series (about 12V). Maximum current would be 2A but smaller is fine too.
energy comes from solar panel so input voltage would be below 18V.
This should not require any processor control.

Any ideas how to proceed?

 

Anyone? Is outdoor battery charging so rear elsewhere than in southern countries?