Confirming diagnosis - bad battery?

[bakalorz]

OK, my float charger took about 20 hours to, but got it up to ~13.03V. After taking it off the charger, it settled to about 12.7V in 1/2-hour.

From there:

11.55V when the lights came on.

10.55V after 10 seconds of cranking.

Put the plugs back in and started it.

12.33V or so at idle. It immediately jumped up to 12.8V at 5k and lingered there. Then I dropped a lead. When I got the DMM hooked back up it was on its way up though. Took almost a minute (I dared not run it much longer than that stationary at 5k!), but it seemed to settle in at ~14.55V.

Was the 10.55V during the cranking, right at the end; or was it just after you stopped cranking, but the battery couldn't recover.

If it was during cranking, your battery is better than mine, which dropped to 9v during cranking 10 secs with the plug wires pulled (but recovered to 12 v within seconds afterward).
(its over 4 years old, and seen some abuse ... I'll probably see if it lasts the season ... maybe next too)

If it was after, the battery is pretty shot, but given that it still starts the bike ...

Regardless, there is still something else wrong with the charging system,
Even a crap battery should still come up to above 14 pretty much instantly as soon as the revs go above 2k or so. That yours doesn't means something besides just a bad battery is going on.

(My crappy battery came up to 13.5 instantly and then above 14 within 5 seconds)

Did you check if the stator has a short to ground (disconnect all the stator leads from the R/R, measure resistance from any stator lead to the batteries ground post. Should be infinite (above 10,000 ohms for sure)

Also, try running with one of the three stator leads dis-connected from the R/R and seeing how it charges. Do it three times, disconnecting all three leads one at a time.

If all three times are worse this is correct.
If two times are worse, but one time is the same as it was with all leads connected then that connection (probably the bullet connector) is not making contact.

[mike_of_bbg]

New (AGM this time) battery installed, and now, yes, it is up over 14V in just a couple of seconds with RPM. Time to go ride...