I've bought a cheap phone (5$) to be a WiFi hotspot and nothing else. Now, the battery is dead. It's a Li-Ion unit, 3.7V nominal (Sony BA900).
Since I do not want to spend any more money I was thinking to crack the phone open, solder some wires on and use a 18650 cell instead of the phone battery.
What worries me is the charging circuit. Does the circuit have current sensing and current limiting to charge a 18650 nicely and keep the magic smoke inside the charging IC? Does battery capacity affect charging?
The 18650's are Samsung SDI branded cells.
Would such a contraption work? Anyone tried such a thing?