Regional Jet 700 ER/LR (CRJ700)
Maintenance Powerplant; Maintenance Airframe
Workload; Situational Awareness; Distraction; Communication Breakdown; Time Pressure
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL
General Flight Cancelled / Delayed; General Maintenance Action
MEL; Procedure; Logbook Entry; Aircraft; Human Factors
CRJ-700 aircraft which had; Main Battery voltage dropped throughout flight in ZZZ1.  Called out Maintenance to defer the Main Battery Charger per MEL 24-32-02 which also calls out for deferring the Main Battery; Flight Data Recorder (FDR) and both clocks. I accidentally selected the incorrect MEL 31-21-01a; instead of MEL 31-21-01b in Saber Maintenance Program that was similar; but wasn't the most restrictive. I did not catch my mistake and deferred incorrectly in Saber program and on Aircraft Logbook as well. I recognize my mistake; it was an incorrect mouse click on my part. I was under pressure to minimize Maintenance delays for the airlines and for passengers. I was stressed in my personal life and having starting my new 12-hour schedule change;rotating work schedule; plus the fact that I was having to do 'everything' with my new job and dealing with an incident that happened five months ago in the ZZZ2 Hanger which I will have to testify in court for another Mechanic/ former Supervisor.
I was was involved in an incident in which an incorrect MEL was applied. A CRJ-700 aircraft arrived in ZZZ in July 2012 with a PIREP for 'MAIN BATT VOLTAGE DROPPED THROUGHOUT FLIGHT.'  The Main Battery Charger was determined to be the cause of the discrepancy.   The Main Battery Charger was then deferred per CRJ700 MEL 24-32-02 then requiring the Main Battery (MEL 24-32-01) both Clocks (MEL 31-21-01) and the Flight Data Recorder (FDR) (MEL 31-31-01) be deferred as well.  The Maintenance Controller and myself ended up deferring the Clocks under MEL 31-21-01A; CAT C; for one clock; but both clocks were placarded.
A Maintenance Controller and Line Mechanic report about applying an incorrect MEL to a CRJ-700 aircraft when they deferred both aircraft clocks under an MEL for one clock.  The Main Battery Charger was also deferred requiring both clocks; the Flight Data Recorder (FDR) and the Main Battery be deferred under different MELs.