Do you mean not turning the engine off? Absolutely not. The battery is the key component in helping the voltage regulator maintain system voltage to a safe level. Without the battery it is possible for system voltage to go as high as 30 volts or more and destroy all the computers on the vehicle. Every year I did that with an alternator on the test bench to show my students what could happen. There's no reason to try to run the engine without a battery.
October, 9, 2012 AT 1:30 PM
MR. ALTERNATOR AIN'T DOIN' IT'S JOB?
RECKON YOU COULD FILL US IN ON THE WHOLE SITUATION. WE DO PRETTY WELL WITH DIAGNOSES'
HAVE YOU HAD THE WHOLE SYSTEM TESTED?
COULD YOU POSSIBLY NEED A NEW BATTERY OR ALTERNATOR?
WHY DON'T YOU HAVE THE ENTIRE SYSTEM TESTED AT A PARTS STORE, LIKE AT ADVANCE AUTO PARTS, THIS IS USUALLY A FREE SERVICE
IF YOU'LL GET HIM BACK TO THE HOUSE (EVEN IF THEY HAVE TO JUMP START YOU), I BET I CAN SAVE YOU A CHUNK OF $$$. INSTEAD OF YOU JUST "GIVING IN" AND BUYING EITHER COMPONENT ON THE SPOT
I CANNOT AID YOU IN THIS PURCHASE UNTIL I KNOW WHAT HAS GONE BAD
SOUND LIKE A PLAN?
October, 9, 2012 AT 7:08 PM
Sorry; I misread that as "change" the battery, not "charge" it. Sure you can use it while charging it, but whatever you're running doesn't care if the current comes from the charger or the battery, ... Well, ... Most things don't care.
Think of a slow, controlled leak in a bucket of water as the current going to run something. The battery is the bucket. The higher the level of water, the higher the voltage. The charger puts water back in the bucket but because it runs on alternating current from the house, it's putting water back into the bucket with pulsating cupfuls, not a steady stream. That results in rapid voltage fluctuations at 120 pulses per second. Computers hate that and may do strange things.
Don't know if that helps or answers the question. If not, you'll have to be more specific with what's happening or what you're trying to do.
October, 9, 2012 AT 7:15 PM
DOC, THAT ONE SORTA HIT ME WRONG TOO
I WONDER IF THEY MEAN CRANK UP THE JEEP---SNATCH THE BATTERY OUT AND PUT IT ON A CHARGER---THEN DRIVE THE JEEP WITH NO BATTERY IN IT?