Can you try login into either of Chargeback database or vCloud database using a client?

The log says, connection to oracle database is not establishing due to limited number of connections.

Might help, refer this link -> http://forums.oracle.com/forums/thread.jspa?threadID=898395.

In short:

select * from v$session;
ALTER SYSTEM SET PROCESSES=500 SCOPE=SPFILE;
ALTER SYSTEM SET SESSIONS=500 SCOPE=SPFILE;

that should do, but to be able to login as system or sysdba, you need to restart listener, that is only if you're not able to connect.

Make sure you are able to connect to either of databases using sqlplus or sqldeveloper clients and then restart the data collector.

-Kartik