My CB77 No Longer Charges the Battery

sarals · Post by **sarals** » Wed Jun 11, 2014 9:01 am

I took my Old Girl out for a good ride yesterday. I turned on the headlight, because traffic was fairly heavy, and I wanted to be seen. I made a stop at a coffee shop, and when I went to leave, the starter labored, but she fired up. I kept the headlight off after that stop. I made another stop, and she wouldn't restart from the starter. She lit off just fine from the kickstart, though, and I was able to get her back home.

Once there, I checked the battery voltage - 10.64 volts. Uh-oh. I started her up, and checked the voltage, at 1300 RPM, from each of the feeders from the alternator - they were just over 6 volts each. I checked the output from the Podtronics, it was just over 12 volts. I didn't rev the engine to see if the voltage rose, I shut her down and put the battery on the charger.

I do have a Podtronics wired in instead of the original rectifier. The Pink and Yellow wires from the alternator have been combined (where they plug into the main harness) and feed a yellow wire on the Podtronics. The Brown wire from the alternator feeds the other yellow wire on the Podtronics. I have the black wire from the Podtronics connected to the battery ground, the red wire goes to the ignition switch, exactly as the rectifier was originally connected. The Pink wire in the main harness is unconnected.

The battery came up on the charger, so it's okay. I know I need to check for a voltage rise from the alternator above 3000 RPM. Now, it seems to me that the maximum output I have seen from the Podtronics was only 12.87 volts, but I will admit that I was looking for a voltage rise with RPM, and not max voltage. DOH!

Ideas?

brewsky · Post by **brewsky** » Wed Jun 11, 2014 9:50 am

One of these worked for me:
http://www.radioshack.com/product/index ... Id=2062584

sarals · Post by **sarals** » Wed Jun 11, 2014 12:38 pm

I've read they work well. The Podtronics does, too. I must have something miss wired.

G-Man · Post by **G-Man** » Wed Jun 11, 2014 2:53 pm

Sara

Have you got a wiring diagram you can share for the Podtronics unit?

Should be pretty simple. AC in from the alternator. DC out. I assume you've got decent air flow over the heatsink? The Brits used to put theirs underneath the headlamp.

You could try checking the two wires from the alternator separately on the AC range of the meter to see if one of the coils has gone down..

Happy to help if you need it.

G

sarals · Post by **sarals** » Wed Jun 11, 2014 3:57 pm

Graham, I just checked voltages from the alternator. The yellow/pink wire (combined wires) is 6.97 volts at 3000 RPM, and the yellow wire is 6.96 volts at 3000 RPM. Those wires feed the regulator/rectifier directly. Output from the regulator/rectifier is 12.87 volts maximum. I think there's a problem with the Podtronics unit.

It's mounted on an L-bracket on one of the original ears for the stock rectifier, so it's right behind the battery. It has good airflow over it. It wires in exactly as the original rectifier did, except I combined the pink and yellow wires from the alternator to get maximum amperage while the lights are on.

I'll e-mail the Podtronics folks and ask them what they think.

G-Man wrote:Sara

Have you got a wiring diagram you can share for the Podtronics unit?

Should be pretty simple. AC in from the alternator. DC out. I assume you've got decent air flow over the heatsink? The Brits used to put theirs underneath the headlamp.

You could try checking the two wires from the alternator separately on the AC range of the meter to see if one of the coils has gone down..

Happy to help if you need it.

G

G-Man · Post by **G-Man** » Wed Jun 11, 2014 4:15 pm

Sara

It sounds more like you have a problem on the alternator side. Are you measuring those voltages with the wires connected to the Podtronics or disconnected. If they are connected up then it is probably the Podtronics pulling the voltage down. Otherwise it is a problem at the alternator end.

7 volts isn't nearly enough. But I cannot see how you are getting 12.8 out but maybe that's just the battery voltage you are measuring?

G

sarals · Post by **sarals** » Wed Jun 11, 2014 8:07 pm

Maybe to all.

What should the alternator voltage be? It's almost seven volts per leg, summed is 14 volts, which is enough overvoltage to get the battery to accept a charge, I would think. To me that seemed about right.

The 12.8 out is the max voltage that the Podtronics delivers, I get voltage rise from it with RPM increase, so it isn't the battery I'm seeing. The battery is sitting at 12.2 volts right now.

I'll run another test tomorrow, with everything disconnected, and report back.

G-Man wrote:Sara

It sounds more like you have a problem on the alternator side. Are you measuring those voltages with the wires connected to the Podtronics or disconnected. If they are connected up then it is probably the Podtronics pulling the voltage down. Otherwise it is a problem at the alternator end.

7 volts isn't nearly enough. But I cannot see how you are getting 12.8 out but maybe that's just the battery voltage you are measuring?

G