Voltage Regulator Problem, Or Alternator Not Charging?

I’m at a loss, but haven’t tried jumper cables yet- to see if my battery is just close to dead.

This morning Rusty fired right up after a couple of weeks sitting idle, which I don’t think I’ve done as long as I have owned it in the past year. This afternoon though, turned the key and my indicator lights turns on so juice, but as I crank the key the system goes dead.

I poked around, didn’t find anything blown, disconnected the battery, arced it out, not a whole lot of spark, but the electrical system had circuit again when I turned the key. And the it went dead again. Arced it out one more time so that I have some juice in the system and got a rolling jump start. I’m up and running until I stop and sit for a bit and then the same problem.

For whatever reason, when I arc out the battery I have circuit again, so it would seem to me that something is “resetting” but since there’s so little spark on the arc, I’m thinking that I might just have a dead battery. But why the “reset”?

 

Try a 'known good" battery. If it starts, the back of the alternator will be magnetic if it is charging.

You really should have a voltmeter and check the actual voltage in your resting battery, and the charging voltage when it is running.

 

Just for gigles clean the battery posts and cables before going any farther.....BTDT....

 

Yeah, that's likely the two most common things to check; bad battery, or corroded battery post / cables.

Arc out the battery? What are you doing? Seems risky/dangerous/pointless.

If you have enough juice to start, you can run the engine for hours on the battery, even if the alternator is not charging. Just driving around won't run the battery down much, unless you are using the headlights.

I'd carefully measure the current from the cable end to the battery with a multimeter, switch off. If there is a significant current, there is a short somewhere in the system. This could be either the VR or alternator, and those can be easily unplugged to test for current drain.

 

I'm not sure about hours but I did get my 3B home 50 miles once without an alternator. My biggest fear was the voltage dropping below the point where the EFI would function. FYI, Pro-Flo 2 still sort of works at 11 volts-------

 

Yes, I didn’t like the idea, but I disconnected one terminal and tapped it against the other, just to see if there was life in the battery (I was at the office so had no tools to test the charge). Seeing as there was very little spark, I suspect I have a battery or alternator issue. The reason I thought it was the regulator (or something else) was because after my test, I had current in the system again. We’ll see in a couple of weeks when I’ve got time to get back under the hood.