Charging Problem - Gonna Need Electrical Help

[bdholsin]

Ok guys, I'm a little confused. My battery died today after riding to work. Let me rephrase that...my battery was low on the way to work. Just after pulling out this a.m. I noticed my blinkers weren't blinking. Ok, no big deal. I rode 15 miles on the highway and when I went to exit I hit the blinker and it was blinking fine.

Parked the bike and put in 8 hours. Went to start it this afternoon and there was absolutely no juice in the battery. BTW, the battery is only about a year old and I used a tender throughout the winter. The old girl fired after a couple of kicks and I motored home. I did notice that, once again, my blinkers weren't blinking.

My thoughts are:
1. Bad charging rotor. I'm yet to pull the side cover and ohm it out.
2. Bad regulator/rectifier.
3. Bad battery. Despite being only a year old, it could be bad. It's on the charger right now.

Let me think this through. The bike won't start with the electric leg but will run after a couple manual kicks. So this means that it's running off the alternator, right? If that is so then the rotor should be good and the regulator/rectifier is bad. Is my logic sound so far?

I'm bone tired tonight and just can't figure out what's going on. I'm open to thoughts/suggestions. First thing I'll do tomorrow is ohm out the rotor slip rings and report back. In the mean time, if anyone has thoughts, I'm listening.

Thanks!

 

[bdholsin]

Almost forgot to add...my entire electrical system is stock. No mods and I'm quite confident that all the parts are original. This is an '83 Heritage Special.

 

[bdholsin]

So I've had the battery on the charger for a couple hours now. It appears to be taking a charge as I went key-on and hit the starter button. It fired up. So I guess I can strike #3 off the list of possibilities. I think I've talked myself into a bad regulator/rectifier.

 

[Dennis]

When I had similar problems I followed Curlys guide and found my answer

 

[5twins]

Your 1st test should be to see if you are charging. Clip a volt meter to the battery terminals, start the bike, and rev it to about 3K. Output should rise to about 14 to 14.5 volts. If you get no change, start testing components. First check is usually the brushes. They are considered a wear item on these bikes. Once they wear too short, charging stops.

 

[bdholsin]

Dennis - That was the guide I was trying to find. Couldn't remember the name of it. Thanks!

Looks like my rotor is indeed bad. I'm getting less than 1 ohm from slip ring to slip ring and less than infinity from slip ring to several engine points that are grounded.

Time to slap in a new rotor.

One thing that confuses me though and you guys can chime in...with a bad rotor, how am I getting enough voltage (with a dead battery) to generate spark? What is generating the voltage?

 

[hotrdd]

If I remember correctly when I fired up my bike and tested the voltage it was 15V at idle and rough the range. Now I'm wonder if that is to much? Or is 14-14.5 just "close"

 

[gggGary]

15 is on the high side but if it remains consistent through the rev range it is likely a meter that's reading high. A shorted "ground" regulator will let the voltage "spike" when you rev it, especially if you know the battery is fully charged.