Ummmm ... I tried using the Coin Battery hack....
All the coin batteries I found were 3.0 volts.
In my tests on an A2000 rev 4.5 MoBo it didn't work.
I needed 3.6 volts for it to hold time.
I know others here have said they have done the hack
with good results, BUT results will probably vary from
one machine to another.
If the coin battery doesn't hold time you'll have to
go the the Barrel battery.
@TjLaZer
Where did you find 3.6 volt coin batteries ??