Is my battery knackered?

[Neosophist]

What do you mean stop working?

I think you have far too much time / think far too much.

The alternator will not charge the battery at idle. You need to be running the engine at a few thousand rpm's before the battery will charge.

Have re-read your above posts it sounds fine.

Junk the rubbish meter.

All you need to test is, alternator not connected (50v AC at 5000rpm between each wire)

Reg/Rec output (measure the battery terminals) around 14v at 5000rpm.

If that is ok then your charging system is working as it should.

[speedy231278]

I agree that without the meter being attached all the time I'd not be worried. Fully charged battery when I got back every time. However, you know by now that I'm neurotic!

Why did the reg/rec that clearly showed it wasn't working before I swapped it out start working again when I made no changes to anything, except plugging a different one in to test? Why was it that EVERY time with the new one, the voltage on the move plummeted for several miles when I gave the bike a good handful for a few moments before going back to normal, and why couldn't I get that to happen with the old one in back to back testing on the same day? Yes, the meter is crap and under-reads, but surely it would behave in the same manner for both reg/recs if both had the same output under the same conditions?

[Neosophist]

I agree that without the meter being attached all the time I'd not be worried. Fully charged battery when I got back every time. However, you know by now that I'm neurotic!

Why did the reg/rec that clearly showed it wasn't working before I swapped it out start working again when I made no changes to anything, except plugging a different one in to test? Why was it that EVERY time with the new one, the voltage on the move plummeted for several miles when I gave the bike a good handful for a few moments before going back to normal, and why couldn't I get that to happen with the old one in back to back testing on the same day? Yes, the meter is crap and under-reads, but surely it would behave in the same manner for both reg/recs if both had the same output under the same conditions?

Many many possibilitles.

Perhaps the reg/rec was shunting a lot of the output from the alternator at the time (battery charge / condition, even temperature) which caused a voltage drop.

Maybe there was a bad connection before?

You have a new battery right? I lost track now.

I wouldn't worry about being able to replicate the exact scenario as long as its working.

The main killer of a reg/rec is heat.

This is caused by two things, shitty connections and old abused battery.

So long as you keep the battery charged up (if your not using the bike regularly optimate it) and your connections dont get corroded up the reg/rec and battery shold last a long time.

[speedy231278]

I have a new battery, but as yet I've not used it as the current one passed the 'charge it and leave it' test with flying colours. I wanted to be sure that it was definitely the battery which was the issue before activating the new one that I have as obviously unlike taking off a spare reg/rec, you can't simply turn off a newly filled battery, and while it wasn't exactly expensive, I'd rather not use it until the existing one requires replacing for sure.

[speedy231278]

Right, now what? I've got back home, and the bike has stood for a month after my exciting day of swapping the new on old reg/recs back and forth. After the having worked for over 100 miles of test riding, give or take the oddities found with the new one, I went to the bike this evening to find a fairly respectable 12.75V on the battery. Started first time, and after spending a few mins chatting to my mate whose, I measured the output to find that there was only 12V at idle with the lights on, where it had previously been more than half a volt higher. There were no signs that there was any real output from the charing circuit. No slight flicker from the lights or instruments, no change in brightness of the lights upon increasing revs. Couldn't do a full test as it'speeing with rain and revving the bike in a garage at this hour would be a bit antisocial. However, the best I managed with a few reasonable blips of the throttle was 12.2V! Bike had not been touched whatsover since I returned from all those miles of tests with the new reg/rec fitted and with the circuit testing out perfectly. I'm going to swap the reg/recs over again, but I'm starting to get seriously pissed off now. To recap:

Alternator windings and outputs check out fine as per advice by Rick O, Neo, Magg, etc. 0.6 ohm per winding and 13V AC at idle disconnected, circa 45V AC at 5K.
Reg/rec output direct wired to battery with heavy gauge wire, fuse and proper battery terminals.
Alternator connector replaced, wires cut back to find decent material, both male and female spades crimped and soldered.
Reg/rec connector replaced, alternator wires cut back, crimped and soldered.
Output much improved when actually working...

Despite the current not discharging unexpectedly over time, is it now time to break out the new battery?

[speedy231278]

And so I go back to swap the reg/rec, check the new reg/rec once more just to be sure it's sulking, and everything works fine without having been touched... aaargh!

[magg]

I can only suggest an intermittent fault in the stator. When the no charging condition occurs again, check the resistance of the of the stator windings including resistance to the chassis.

[speedy231278]

Last time that happened, I checked it literally the second it happened and all was well. I've got a spare stator, but as yet no tool to remove the flywheel. This is driving me nuts!

[magg]

Infinite resistance from windings to chassis?