AS THE ACFT WAS CLIMBING THRU 19,000' AT NGT, THE #2 GENERATOR (GEN) LGT CAME ON. THE FLT CREW NOTED THERE WAS NO OUTPUTFM THE #2 GEN & IT WOULD NOT RESET. THEY THEN CHECKED THE #1 GEN VOLTAGE & NOTED IT WAS 14 TO 15 VOLTS. THE CREW REDUCEDTHE ELEC LOAD; HOWEVER, ABOUT 5 MIN LATER, THE BATTERIES BCM DISCHARGED & THERE WAS A TOTAL LOSS OF ELEC PWR. USING A FLASHLIGHT, THE CREW DIVERTED TO THE CHESTER COUNTY ARPT WHICH HAD A 4600' RWY. THE GEAR WAS EXTDD WITH THE EMERG SYS. THE ELEV TRIM WAS INOP, SO BOTH PLTS APPLIED BACK PRESSURE ON THE YOKE TO OVERCOME THE NOSE DWN TENDENCY. AFTER LNDG ABOUT 1/4 OF THE WAY DWN THE RWY, THE CREW TRIED TO USE THE THRUST REVERSERS, BUT THE REVERSERS WERE INOP. SUBSEQUENTLY,THE ACFT CONTD OFF THE SIDE & BEYOND THE END OF THE RWY, HIT A WOODEN BEAM & A SNOWBANK, THEN CAME TO REST IN A DITCH. AN INV REVEALED A SHAFT FAILURE OF THE #2 GEN (STARTER/GEN) & WORN BRUSHES IN THE #1 GEN. WITH TOTAL ELEC FAILURE, THE FLWG WERE ALSO INOP: WING FLAPS, ANTI-SKID, CAPT'S AIRSPEED IND & ALTIMETER, NOSEWHEEL STEERING, COCKPIT LIGHTING.