It is not "Constantly" trying to update, and therefore it is not
constantly using your battery.
Autosync only transmits when the other side has something to send. It
doesn't constantly ask if there has been a change that needs to be
This is accomplished by opening a socket to the server, then putting
the radio to sleep. The socket stays open until server attempts to
send something, or the socket times out. TCP/IP sockets typically time
out anywhere from 12 to 18 minutes after they are opened.
Each time the radio listens for traffic (which in GSM land is every
120 milliseconds) it will see that traffic is waiting if EITHER the
socket timed out or the socket became readable (has data waiting). It
would then power up the radio enough to read the data, or reestablish
the timed out socket).
Your phone is doing that all the time, 24/7 365 whether you have
autosync on or not. That's how cell phones work. It takes virtually
So if you sync your Gmail, Contacts, Calendars, Picasa, Documents,
Books, Music, Reader, all of those things you sync with Google are
handled by ONE socket. That one socket gets set readable when there
has been any change in any of those services that needs syncing.
Add another socket for Dropbox, or skydrive, or any non-Google mail
(For non-google mail accounts ALWAYS choose IMAP accounts, never POP3.
Pop3 has to wake up and check mail. Have your gmail account pull mail
from pop3, and get that account off your phone. IMAP accounts use IMAP
IDLED, which works on the open socket method described above, as does
The vast majority of these services go hours if not days between any
changes, so there are very few times that data needs to actually be
synced. Most of the time its just a socket refresh. And all of these
tend to happen at one time, because Android tries to get them to all
drop at the same time by starting them at the same time when you
bounce from one tower to the next or switch from cellular to wifi.
But the key point to remember is that your phone is ALWAYS talking to
the towers anyway, every 120ms, so these socket refreshes take almost
zero extra power.