20 - 30 minutos
The battery life on my iPhone 3GS was dismally short and so I wanted to replace it. I found iFixit.com on the internet and after reading about how to do it, I decided to move ahead and buy their replacement battery kit.
I followed the online instructions on iFixit.com for replacing the battery for the iPhone 3GS and it went surprisingly smooth. My kids watched me do it and learned a valuable lesson. The lesson being: "Hey, you can fix stuff!".
My advice would be to read all the instructions and advice given on iFixit.com before doing the repair by yourself. There's experiential knowledge (wisdom) to be gained by those who've gone before us.