Sorry to ask about this again, but different symptoms this time.
Fitted my new Lithium Iron battery after charging it with the proper charger to over 13V.
I have a voltmeter on my bike like this: Motorcycle Volt Meter - webBikeWorld
Rode to work (60 minutes), voltmeter read between 12.5V and 13.7V all the way, even with headlamps on, even when idling. Battery 13.1V when I arrived at work.
8 hours later, time to go home, battery @ 12.8V, started first time. After 3 miles, hit very heavy traffic at Vauxhall, couldn't even get the bike through. Fan came on of course.
Then the voltage dropped rapidly and bike died. Couldn't restart her, lights all dim, not even a click from the starter relay. Thankfully a taxi driver gave me a jump start (I was carrying my jump leads!).
2.5 miles later, she died again. Battery read 7V! Dim lights, not a sound from the starter relay. Called the RAC, he rapid-charged my battery up to 13.2V in about ten minutes. He suggested I use just the parking light to get home but I didn't feel safe so used headlamps. For the next 12 miles, the battery read between 12.5v and 13.4V, and 13V when I switched off the ignition.

So why does it lose voltage quickly then perform well?

Thanks again.

 

Are the battery terminals tight and all ground connections to the frame tight and free of corrosion?

 

I'd check the connection between your alternator (stator) and the battery. Located under the left rear quarter panel. It has a multi connector plug. Make sure all connections are tight and no signs of melting.
It sounds like you have a partial short in the main power line to the battery - sometimes it'll charge, other times not.
I had the same symptoms when my multiplug developed a fault.
It could also be your reg/rec on it's way out.

Also, remember the bike will only charge above 3500RPM, so at idle the battery is constantly draining. Guys who have electric heater jackets and grips sometimes have trouble in traffic with keeping the engine running.

Some of us have fitted Electrex Reg/rec's which start charging at much lower revs - mine gives me 13.8V at 1800RPM. They have a higher charge rate of up to 15.5V depending on the state of your battery. They also have a heat sink which helps with overheating ( don't ever touch your reg/rec when the bike has been running, you'll burn yourself)

 

Hi Howard,
I have nothing to ad to Shadow's words which seem the best place to start fault finding. Given that my bike has been standing for a disgustingly long time without use it's likely I'll be in the market for a new battery before long and have been eyeing the Lith-ion batteries.
Your feedback on the new power pack would be most welcome, assuming you find the gremlin.
Good luck and please do update this for future reference.

 

I can't add to Shadow's input either. I would however look very closely at the wires coming from the ALT where the pass through the case. Other than that, sounds like a loose wire in the charging system or a short somewhere as stated above.

 

Thanks for your replies and avice folks.
Today going in to work she performed faultlessly with and without headlamps on.
Coming home form work she performed faultlessly with headlamps on all the time (though voltages were about 0.5V lower).
So I reckon I must have a loose connection that maybe gets worse when the bike gets really hot. If the stator was shot she'd never charge the battery, right?
The connector between stator and RR was melted long ago - I now have bullet connectors instead.
And four individual spade connectors to the starter relay.
And the old starter button is now removed from the loom.
I might leave the LiFe battery in the bike overnight (outside) if it looks healthy around midnight. If not I'll hook it up to its charger. I still think I have something draining the battery slightly though.

 

OK, here's a quick way to see if there's any kind of significant drain on the battery while everything is apparently turned off.
Remove the earth from the battery then connect an ammeter between the battery and the earth terminal. Any drain will show up on the meter. If your meter has more sensitive settings then you can find out in milliamps if it's below an amp and hard to read on a 1-10amp scale, for example.
Just hope you aren't pulling more than 10 amps. most meters will fry able that and if you are your battery will also be getting hot, very!
Even half an amp being drained will flatten it pretty quickly. If you're sure you've got nothing like an alarm or possible even your volt meter, which might be causing a drain connected and you're still getting a reading then it's time to start pulling connectors to narrow things down. I hope you don't need to do any of this. Life's too short, especially when you get halted in London rush hour on a bike. I know, it's madness. Just be thankful you have more brains than the average car driver. Why do they do it?????

 

Yes - as I was pushing my beast along the one free lane of the Vauxhall one way system a to$$er in a white van kept using his horn at me to get out of the way. So I stopped pushing, turned and looked hard at him. He didn't even have the cojones to return my stare.

On the bright side, the RAC turned up within 15 minutes of my call and the patrol man was really friendly.

 

I'd suggest one more test - get the bike hot (idle it until the temp gets up to where the fan kicks in.) I'd then check the charging rate going into the battery. Also remember that in traffic below 3500RPM the battery isn't charging. The combination of that and the fan running may be enough to flatten a battery where the reg/rec is old.
Just a thought.

 

hmm, in your other thread you have a sound coming from the cooling system. I wonder if the fan is sticking now and then causing the periodic drain on the charging system. If the fan is sticking, it would cause over heating and the coolant would boil also.

I wonder if the two problems are related due to the fan. If you unplug it does the charging problem go away? Can you do a ride where you know you won't need the fan to check out this theory?

edit: This is taken from yet another of your threads;
Looking at the wiring diagram, the fan gets power directly from the ING switch. If the fan were to stick, it will pull power from wherever it can to satisfy its hunger. With the switch in the on position, it looks like it can pull from lesser fuses, through the switch, blowing them. With the switch in the park position the fan may not be required to run and it wouldn't blow other fuses.

I think all three problems are related to either the fan sticking or the fan's thermostatic switch and/or a short in that particular system.

I could be way off base and the real problem may be that the Mayan calender has been expired for some time now.