Other option is buy a spare battery or 2, get a battery caddy charger and swap batteys every day.
Swapping an iPhone battery isn't as simple a task as you think Skrunts, the handset has to be taken apart (literally) in order to replace the battery on an iPhone
I just got a Galaxy IIS, first thing I got after that was a docking stand, drop the fone into it, it charges and sycs data to PC (once I can get a program to work with it) but can move MP3 and pics about with no probs. Plus I also got the spare battery and battery charger/caddy. Plus geared up with car charger etc. (Amazing how much they go flat downloading appz while Mrs Skrunts is in the supermarket. 
Be careful if the spare battery/charger is a cheap chinese clone (eg, Anker) Skrunts, quite a few S2 owners have had them explode/catch fire when in use.
Going back to your other problem regarding not being able to sync with Kies correctly, were you using the dock when you were trying that?
If the answer is yes then you need to take the dock out of the equation and connect the handset directly to the PC via the supplied USB cable.
I would also recommend you ditch Kies in favour of a piece of software called MyPhoneExplorer.
It's completely bloat free (circa 4MB), urinates all over Kies for what you can actually do with it, and unlike Kies it won't install other 3rd party software behind your back that you cannot remove afterwards.
The MyPhoneExplorer client for the handset can be downloaded from the Android Market
>HERE<The MyPhoneExplorer main application which goes on the PC can be downloaded from
>HERE<My antivirus proggy (NOD32 by Eset) throws a little wobble when I select the downloads page for the main application, but I can assure you that it is nothing more than a false positive if yours does the same. Pay attention when installing the main app as it will install a 3rd party toolbar (Babylon) by default unless you tell it not to.
Lastly, you will need to enable "USB Debugging" on the handset itself as the Sammy MTP application (which is crap anyway) will cause issues when trying to connect.
To do this, go to Menu > Settings > Applications > Development and place a tick in the relevant box
After enabling USB Debugging, you will have to manually tell the handset to connect to the PC under some circumstances in order to stop the MTP application from interfering with things. To do that, drag the status bar on the handset down and you will see an option in the notification area that says "Select to copy files to/from your computer".
Once this is selected, you will be presented with a picture of Andy (the droid) in green with a button underneath that says "Connect USB Storage". When a successful connection is made, Andy will change colour from green to orange to indicate connectivity.
To safely disconnect once you are done, simply press the button underneath the orange Andy that says "Disconnect storage from PC"
Hope the above helps, and if you want to know anything else about the SII then feel free to ask.