Topic: Battery dying: differential diagnosis?

[TwoTired]

The white and green wires are supposed to be power to the alternator.  Zero volts means it is shut down completely, and can't charge anything.  How is your battery getting over charged?

What is your battery voltage with the alternator reved?

[TwoTired]

What's on the white and green with the ignition on and the engine not running?

[BobbyR]

If you are speaking about your 78K I have the same bike and was having a dying battery problem. I dug into the factory manual and did their tests which all come down to adjust the regulator with the engine running at 3500. I cleaned the contacts and then adjusted the voltage to 14. Works good.

[medic09]

What's on the white and green with the ignition on and the engine not running?

I'm still getting 0.  Green/black show about 11.48, like before.

 

[medic09]

If you are speaking about your 78K I have the same bike and was having a dying battery problem. I dug into the factory manual and did their tests which all come down to adjust the regulator with the engine running at 3500. I cleaned the contacts and then adjusted the voltage to 14. Works good.

This is a solid-state replacement reg.  There's nothing to adjust.  Though I may have to replace it...

[TwoTired]

What's on the white and green with the ignition on and the engine not running?

I'm still getting 0.  Green/black show about 11.48, like before.

 

I don't think your regulator is working anymore.  Or, maybe you have an open circuit to the alternator field coil.  (I don't know the internal circuitry of your non-stock regulator.)

Can you measure resistance across the disconnected white and green wires.  S/B about 7 ohms.  If you get that, then replace the regulator.

Cheers,

[medic09]

What's on the white and green with the ignition on and the engine not running?

I'm still getting 0.  Green/black show about 11.48, like before.

 

I don't think your regulator is working anymore.  Or, maybe you have an open circuit to the alternator field coil.  (I don't know the internal circuitry of your non-stock regulator.)

Can you measure resistance across the disconnected white and green wires.  S/B about 7 ohms.  If you get that, then replace the regulator.

Cheers,

8.1, if I measure correctly.

[coyotecowboy]

It sounds like you've already ruled out the battery, but for future reference, we check batteries at the shop like this

1.  disconnect battery

2.  hook up battery charger (not just a trickle charger, a regular charger with a boost/start setting)

3.  hook up your battery tester on top of the charger leads

4.  turn it to fast charge, give it a few seconds for everything to come up

5.  turn the charger to boost/start for a few seconds only.  If it pegs your meter, your plates are shorted, period.  Replace the battery, put it on a low charge for a little while (45 mins to an hour so your alternator isn't having to work so hard to catch up), fire it up and check your output.

If your battery is even a little iffy, get rid of it, it'll only cause you troubles on down the road.

[medic09]

Well, I put the original voltage regulator back in.  At 4000 rpm the voltage across the battery posts peaked around 14.2.  I guess I stick with that for now.

Thanks guys!