(I solved my particular case on another thread, and I'm trying to share my solution, so please, pardon my copy-and-paste post)
It is a syncing error loop. My contacts are syncing flawessly again between my devices and iCloud, and yes, the battery stopped draining, which is the main topic here.
I followed instructions from buxbuster (look for his workaround in the thread link below) and an additional BIG step to restore contacts and syncing, as seen in a MacRumors forum.
This is what I did:
1. Make a backup of your Address Book, using the vCard option (or both, it doesn’t hurt). Save it for later.
2. In your iPhone, delete iCloud account. When it asks, accept both: delete AND delete from my iPhone.
3. Reset network settings. The iPhone will restart, then will ask you to unlock the SIM card.
4.Turn Wi-Fi on.
5. Add the iCloud account again.
That’s for Buxbuster’s workaround. For some, it might work just like that. My iPhone repopulated from iCloud after step 5, but I still had that “server error” on iCloud. I had to do some extra steps, since my Mac was not syncing to iCloud and couldn’t edit anything on my Mac or iCloud. Syncing back had to be fixed, too. If not, the syncing loop would continue from my iPhone, and the battery would drain awfully again.
1. In System Preferences -> iCloud, I turned Contacts off. I chose “keep on My Mac” those contacts, but I got an empty Address Book after a while. And a few minutes later, iCloud contacts were empty and my iPhone also. It is scary at first! Now, before importing that vCard backup…
2. Turn Wi-Fi off. This is important, since your contact-empty iCloud will attempt to wipe your Address Book from your Mac in seconds after importing.
3. Import your vCard backup to Address Book. Just drag it to your blank Address Book window; it asks if you want to import “x” number of cards. Of course, say yes.
4. Turn Wi-Fi on, and then iCloud contacts on again (System Preferences -> iCloud). It will offer to merge your newly populated Address Book with iCloud (which is empty at this point). It should upload every single contact to iCloud, and then to your iDevices. If not, a fifth step would be to import the vCard file to iCloud, but it shouldn’t be necessary.
So, with iCloud syncing working correctly, there is no battery draining! Again, that was my particular issue.
I can’t tell if this is the single answer to the widely spread battery draining problem, but it sure can be fixed with these workarounds, and yes, Apple should address the problem with a future update, for we affected customers don’t need workarounds in the first place 😉
This is the MacRumors discussion:
http://forums.macrumors.com/showthread.php?t=1256807
And the other thread:
https://discussions.apple.com/thread/3391947?tstart=0
Dont’ forget to check buxbuster’s fix, video, and THANK him!
Hope it helps some.