Backup jailbreak

I can see two main possibilities:

1. Apps like FolderCloser, NoLockScreen, and SBSettings shorten battery life by requiring heavy background processes. The only solution to this would be either to not install these apps or restore the phone to its original state altogether (and not have these apps installed). I am convinced that jailbreaking allows for processes that are not in phase with Apple's careful thriftiness of battery use.

2. Your battery is not calibrated properly so your iPhone miscalculates the remaining percentage. The solution here would be to drain your battery completely and then fully charge it.

Good luck! And know that you can restore the phone to its original state.

You can't update your phone to iOS 5.0 Not even if you have your SHSH saved. So nothing you do will allow you to install 5.0 right now. At least for the time being. Your only option is 5.01. The problem is that apple is no longer signing 5.0 and no shsh blobs will help you neither because a new security measure implemented on all 5.X

So if you need an unlock in order to use your phone I would highly recommend not updating to 5.01 because UltraSnow is currently not working on 5.01 despite of what baseband you have. No even with 1.59 baseband (but this is just until ultrasnow is updated to work on 5.01) If you don't need an unlock then you can safely update to 5.01 and do a tethered jailbreak using the latest redsn0w and pointing the ispw to 5.0

And before doing anything please update to the latest iTunes.

I hope this helps.