While using the phone it randomly shuts down. And when I turn it back on battery drains by about 3 or 4 percent. Could this be a battery problem or a sign to another major problem? So the only way I use my phone nowadays is while its plugged in. Battery also drains like hell. While using 3G battery goes from 100 to 50 in an hour. Are the random shut downs related to the excessive battery drain? Just last month I changed my battery IC beacause it displayed the " charging is not supported with this accesory" warning.
It sounds like you need to backup your iPhone with iTunes and change your battery... but I'm a little confused by your post. You have tried to put a new battery in it already? If so your issue is probably related to other internal components of your phone and not the battery. The 3GS is quite old now. It may be time for an upgrade.
The battery draining down a few percents is normal behavior, but going from 100 to 50 in an hour is not (unless you are running some crazy large processes). The 3GS is an old phone, so that wouldn't surprise me that the battery life is a bit sketchy. My advice would be to have the battery replaced. I'm unsure of if your data will be lost during the process, I don't think it will, but back it up on iTunes first just to be safe.
Second, no the random shutdowns are probably not related to your battery issue. If the phone randomly goes black and fades away, that's a battery issue. If the phone goes through a proper shutdown, then it is not. My advice would be to do a total restore, and if that doesn't work, it's a hardware issue.
I had the same problem. Your battery is dead, plain and simple. So you basically have tree choices:
- buy a new iPhone;
- replace your battery, but that might damage your phone if not done properly and may end up costing more than you'd want;
- buy an external battery and let your 3GS be permanently plugged into that battery. They make pretty nice shell cases with embedded batteries, you may want to have a look at these.
Make sure that there aren't any background apps processes running on your iPhone. Insufficient memory on your iPhone could cause it to restart while memory-intensive processes could drain the battery quicker than usual.