Hi, I have few samsung batterys rated 2600mAH 3.7V so they have four pins 1 Vcc and other three gnd which means 3s battery so if i would be using it in a project how could i charge them like which circuit shall i use
A 3.7V battery is NOT 3S. 3S li-ion/lipo = 11.1V nominal.
Samsung mobile phone batteries 4 terminals are usually +, -. temp and a 1-wire data pin (probably not in that order). If you don't know what you're doing it's best not to mess with them.
Photo would be worth a thousand words..
I tested 1st terminal is + and 3rd is negative and this is link to battery https://www.amazon.com/Replacement-SM-J500F-2600mAh-EB-BG531BBE-Battery/dp/B07G9YHFKX