Programmable Timer?

Question

Im trying to build a programmable timer that will stop a cell phone from charging after 3-4 hours to stop the battery from swelling. I dont want to buy one. How can you do this? Links are very helpful.

Answer 1

It would be much better to build a charger that looks at the condition of the battery rather than just running for a period of time, although the circuit becomes a little more complex.

You need to identify the battery type and voltage, although I am bemused as to why your cell phone doesn't have these circuits built in.