[Rich Mintz]

Per Arizoni:

Tester leads inserted securely in battery terminal blocks.
~13.2v with key off
~12.89 with key on (headlight)
~12.81 started and at idle in neutral
No change (12.80-81) when I rev the engine in neutral

Is this conclusive evidence that the charging system is at fault?

[Ducati Scotty]

After a start it takes a while to recover and the voltage may not go up until it does.  Go for a 10 minute ride and DON'T turn it off when you get back.  With it still running get the probes on the battery, then rev it.  If it doesn't get to at least 13.5 you're not charging.

Scott

[barenekd]

I have to disagree. It should be showing a bit more voltage than usual for a few seconds after startup just to get a fresh charge going in the battery.
That's what I've always seen anyway. There will be a slight tendency to spike at that point.
Bare

[Rich Mintz]

Rode 15 minutes in normal traffic, tested at battery with engine still running: 12.57 volts, down from 12.81 when I started it. So apparently I am not charging, either because of a charging system fault or because the battery won't hold a charge. But I can charge the battery off the battery tender, so I'm guessing its the charging system?

Stopped with the key off, battery putting out 12.85, down from 13.15 before I started it.

[Ducati Scotty]

Nearly dead batteries can make it look like the charging system is failing.  If you put a fresh battery in there I bet the voltage comes right up.  If not it's your charging system, but you've already got a battery on the way   You'll know soon enough.

Scott

[Rich Mintz]

Yep. I might not even wait, I might go buy a battery tonight to be done with it...

[Ducati Scotty]

I have to disagree. It should be showing a bit more voltage than usual for a few seconds after startup just to get a fresh charge going in the battery.
That's what I've always seen anyway. There will be a slight tendency to spike at that point.
Bare

I've got a volt meter on my bike.  It won't come up right after a start.  You've got to give back a little of what the start took out before it comes up to full charging voltage.  That's usually  a few minutes or riding or revving.

Scott

[Ducati Scotty]

Yep. I might not even wait, I might go buy a battery tonight to be done with it...

Weather's that good, huh?

Scott

[Arizoni]

Assuming all of this testing was done after you fixed the failing ground connection, your test results does indicate a fault in the charging system.

A lot of things can cause this but the first thing to check is all of the electrical connectors and ALL of the fuses.
If the one from the alternator (3 yellow wires) to the voltage regulator is loose it won't charge the battery.  If the red and black wires from the regulator are loose, it won't charge the battery.
If the small black wire that is connected to the heavy black ground wire coming from the negative post of the battery is loose or disconnected the alternator cannot charge the battery.

Electrical problems are always a PITA to track down but your new volt/ohm meter can help.
Remember, if it is set to read resistance on any of the Ohm settings the test leads should always give a reading if both of them are connected to something that should be capable of carrying electric current.
For instance, if one test lead is connected to the battery end of the ground wire, touching any other bare metal place on the engine should give a reading.  If it doesn't either the wire is defective or it is not hooked up to the engine with a good connection.

Using this Ohm feature can often find "open" circuits to track down a problem.

All that said, if the motorcycle is still under warranty and you have a dealer handy I'd let him try to figure out where the problem is.

[Rich Mintz]

Living on the edge! I rode to pep boys to buy a new battery - and they don't have sealed AGM batteries to fit! So I bought a portable charger (which I wanted anyway, to carry on the bike until this is conclusively solved) and am taking an hour of charge into the battery before I ride home. Battery was at 12.81 when I got here, so it will probably start the bike - but I'd prefer not to have the bike die in the middle of the Holland Tunnel if possible.

Tomorrow, wiring check. I visually checked the obvious, but I'm guessing I need the seat off to do a real check, and that's a whole project...