A CE152 ON A TRAINING FLT IN BUR AIRSPACE; HAS THE ALTERNATOR SWITCH ACCIDENTALLY PLACED TO THE OFF POS. WHEN THE ELECTRICAL PROB IS DIAGNOSED; THE ALTERNATOR SWITCH IS FOUND OFF AND RETURNED TO THE ON POS. HOWEVER; WITH THE BATTERY DRAINED; THE ELECTRICAL CHARGE IS SO GREAT THAT THE ALTERNATOR BEGINS TO FAIL.

Narrative

MY STUDENT AND I WERE ON A TRAINING FLT. AFTER ABOUT 45 MINS OF FLYING WE NOTICED THE LOW VOLTAGE LIGHT WAS ON; AND DISCOVERED THAT THE ALTERNATOR WAS TURNED OFF. MY STUDENT MUST HAVE KNOCKED IT OFF WITH HIS KNEE DURING THE FLT BECAUSE IF THE ALTERNATOR HAD BEEN OFF SINCE TKOF; WE WOULD HAVE LOST ELECTRICAL PWR LONG BEFORE THAT. SO WE TURNED ON THE ALTERNATOR AND CONTINUED. ON OUR DSCNT TO BUR; OUR HOME PORT; WE LOST COMS AND ELECTRICAL PWR. WHAT HAPPENED WAS THAT AS WE RESET THE ALTERNATOR IT BEGAN TO HEAVILY CHARGE THE BATTERY; WHICH SET OFF THE CIRCUIT BREAKER. AFTER THE CIRCUIT BREAKER WAS TRIPPED THE ALTERNATOR WENT OFF-LINE AND WE WERE JUST USING THE BATTERY. THE BATTERY DRAINED RELATIVELY QUICKLY AND WE LOST OUR ELECTRICAL PWR. I MADE A PRECAUTIONARY LNDG AT A NEARBY ARPT (CLASS D) SINCE I HADN'T MADE CONTACT WITH BUR TWR YET. AFTER LNDG WE DISCOVERED THE POPPED-OUT CIRCUIT BREAKER AND GOT BACK SOME ELECTRICAL PWR. APPARENTLY; AS THE MECH TOLD ME LATER; SOMETHING WENT WRONG WITH THE ALTERNATOR BECAUSE IT WASN'T CHARGING PROPERLY. WE HAD ENOUGH PWR TO RETURN TO BUR AND GNDED THE AIRPLANE UNTIL THE PROB WAS FIXED THE NEXT DAY.