Oklahoma_Mike wrote on 12/31/69 at 16:00:06:Hey I think my battery is dying but I wanted to check my charging system and noticed that with the motor running when I disconnected the battery the bike died. I rode 340 miles last weekend and the bike didn’t give me any problems. So what’s the deal. Shouldn’t the bike stay running with the battery disconnected? If not how does the battery get charged. Is anyone else’s rig doing this as well? I tried playing with the throttle to try to keep it running no luck. I know quite a bit about charging systems but am at a loss if the bike is not charging the battery should run out after about 10-20 miles max but I drove it 40 miles to work and back and ran to a few stores on it, starting and stopping and the battery seemed strong. ps pretty sure the battery is on its last leg. where could a guy locally find the drycell Odyssey battery. Part number? 8)
Why will the engine die with the battery disconnected? Good question. Forget the days of magnetos...
The engine dies because the ignition system needs Direct Current voltage to operate. With the engine running, the alternator is sending Alternating Current voltage to the regulator/rectifier. From there it goes to the battery and the rest of the bike. With power flow from Positive to Negative, just consider the path to be broken without a battery.
On another note, the bike WILL run for a limited amount of time on just the battery, if the charging system fails.