Still having charging problems!

Some have followed this. Broke off a battery post and just fixed it. Then yesterday I took the battery to a shop where it was fully tested (they thought the post fix was good by the way). The battery showed the right voltage, amps, and speciic gravity. The battery is good. A few weeks ago I put in a different voltage regulator/rectifier, and it tested at about 13.8 volts (at battery) just above idle, so I see no problems there either.

Yet, if I start the bike from cold, and ride it more then 2 miles (say to go to the store) then come out and try to start it, it cranks slowly and doesn't want to start. It eventually does and I get home, but these are short rides, and it gets worse with more miles requiring recharging the battery at home.

Other things I've done are to check and clean all connectors, wires, grounds, the stator output (good), rebuilt the starter, etc. I even pulled the + cable off the battery and read from it to the battery for voltage leak with the bike off. No leaks.

None of this has helped. The battery still starts dragging down after only a few miles. Can a battery pass the tests and still be bad? Any ideas from anybody? Thanks!

if a post broke and was fixed it could come loose agian under vibration borrow another battery and see if this reoccurs

Hasen't come loose, and the battery cranks fast and strong just after charging, so I doubt that's the problem. The only other problem I can think of is the R/R, but it seems to be working fine.

I'd say put a meter on the battery and read what the charging voltage is at idle. I believe 14.+ is what you need, 15 will boil the battery/blow light bulbs.

Get a small voltmeter and connect/tape the leads to the battery, then tape the meter to the tank and go for a ride.

The voltage should be 12.8+ while idling.
Volts should rise up to but not above 15V while accellerating 4000+ rpms.

Starting the bike from cold, the meter should read around 12.6 V (if the batt has rested/no charge for few hours.)

Turn the ignition on and check: voltage will drop to 12.4ish, and continue to drop .01 volts every 5 seconds or so.

While cranking to start, the voltage usually drops hard to around 9-10 volts, I've seen some go as low as 5-6, but if it drops way down to 3 or less, either the battery is bad, or the starter needs to be overhauled.

Restarting warm, batt will still be 13+ volts, and should crank starter pretty hard if everything is ok. If not, then likely a starter issue, or bad ground/wiring.

GL!

Like I said above, it's about 13.8 at maybe about 3-4000, and at idle it's around 12.5 or maybe a bit higher. Don't think the R/R is at fault.

Seems to be the battery (and probably the repaired break), although after charging with a charger the battery spins the starter quite quickly. Still, it might have a weak cell that discharges quickly. It's the only thing that makes sense. If the post broke again to the point where the battery wouldn't take a charge, I doubt it would spin the starter very well either when charged. The only other battery I have is sulfated, but I'm going to try to clean that up tomorrow.

Yes, as I said above, the starter was just rebuilt (new brushes, seals, bushings and bearing). Spun quite nicely before re-install, and works fine in the bike with a fully charged battery. Doubt it's the starter.

Is my confusion understandable?

Would charge battery overnight, and then have it load-tested.

Good Fortune!

Would also assure integrity of connection where negative battery cable attaches (grounds) to rear of engine.

Good Fortune!

With everything off, could detach negative battery cable, and measure for any current draw between negative post and engine, and also between negative post and frame.

Good Fortune!

IMHO 13.8V at 4000rpm is barely good enough. It needs to be closer to 14.5V if it is going to charge anything.

You may want to try running without your headlight to see if this raises the voltage. If it does, then you've got too much load for your generator to handle and the battery isn't getting enough juice to recharge after being used to start the bike.

That being said, a proper sized battery should be able to start the bike half a dozen times before going dead, so I am almost certain that you have something draining your battery while you are riding. That or your battery is way too small (<5Ah).

Polkat,
you replaced the R/R and repaired the battery post? But you may have a dirty or loose connection between your Stator and the R/R, or from the R/R to the battery + post, or the R/R ground wire. All of these need to handle both Voltage and Current load (Amperage).
You have Stator wire connections behind the left hand sprocket cover, a ACV test of the Stator should be done if you haven't yet.
There has been many threads in the past few weeks covering Stator and charging system testing, both unloaded by the book and with the full rated output test.

Thanks all for the ideas. I have checked every connection, looking for looseness, dirt, corrosion, etc. I have tested the stator and all three combinations are putting out about 50 volts at around 4000rpm, have checked grounds and other wires, and all connections to and from the R/R and starter, and so on.

Right now the battery reads around 12.5 volts at idle and roughly 13.6 at around 4000rpm (it does not go higher with higher rpms). These readings are with everything on.

Could a weak/dead cell in the battery be causing this?

Note: These readings are with an old analog VOM and not digital. Maybe my meter is out of calibration, but either way, the battery still discharges.

Any further ideas? Thanks!