jetblack wrote:So, i'm intreigued to know how this happens. Can anyone clarfiy whats gone on for me?

General ill health and lack of maintenance in your charging system is usually the cause:

• The first root cause of most issues is often poor earthing. Either the main earth from the loom to the chassis, or the battery terminal earth (either end). Keep these clean, and lubed with silicon (di-electric) grease.
• If that is not your cause, then it's probably green corrosion build-up in the plugs between either the loom and the regulator, or the loom and the alternator. The green build-up causes increased resistance in these plugs (which are already only just big enough for the current involved), which usually then takes out the regulator. When the regulator goes, it will usually take out the battery next, and then the alternator. If you clean them up and stuff with silicon grease, you will not have this problem.
• If that wasn't your problem, then it was the regulator overheating. This can happen on bikes with powdercoated subframes, as the powdercoat insulates the frame so the regulator cannot evacuate heat out the back into the frame. The solution to that is fitting a finned regulator so heat can escape out the front of the unit instead. Also dirt and occasionally corrosion can get in at the back of the regulator, causing the same problem. Air gaps are your enemy here, so if the mounting plate is bent you also have a problem. If you clean it and fill with silicon grease, you won't have that problem. Usually though, regulators melting is a symptom, not the cause. If you find you need a new regulator, you would be daft not to do the other checks above.
• I think it's quite rare for alternators to just fail on their own? I have never seen it except where caused by a failed regulator or a dodgy alternator connector. Although I guess it would be possible for it to just overheat, that'd potentially be caused by running at idle for far too long, and/or having old oil that could maybe deposit (metallic, conducting) sludge on the windings. Again though, that's only theoretical and I have only seen failed generators in conjunction with something else as the cause.
• I suspect a failed battery (eg. if it fails by a cell shorting out rather than just by the acid losing potency and not holding a charge any more) might also have potential to be its own root cause. Hard to diagnose accurately, as in cases where the regulator fails it'll take the battery out quickly, so you won't know which gave up first. In any case, if your battery is "going" then don't let it wait til payday, change it now, or it may just take out the rest of your charging system. As a guide, expect cheap batteries to last about 2 winters, and Yuasa batteries to last up to 4.

That's all just IME, but I've had and seen enough problems to think I am pretty close to the truth. So if you spend an hour or two with some wire wool and silicon grease, you can proof your charging system against most faults - very near to all, I would say - just by cleaning up two plugs and the back of your regulator. It is possible to pop the spade plugs out of the connector block, and advisable to do so.

Cool, thanks.

i only got the bike a short while ago and it was generally in a good state although i have found a few things that were a little bit questionable. i've now recitified these things.

So now my charging system has a brand new battery, a used R6 reg/rec with the subframe filed flat and thermo grease applied to the back of the reg rec to help dissepate heat. and once it arrives, some used but tested and working windings so essentially a refresh of the whole charging system. i've cleaned up the earth connections (although they looked like new to be fair) so hopefully this should all put me right.

Is red rubber grease the same a silicone grease? If so i've got loads of this so i will use that to coat my battery terminals, otherwise i have some of the thermo grease left over- is that suitable?

jetblack wrote:Cool, thanks.

i only got the bike a short while ago and it was generally in a good state although i have found a few things that were a little bit questionable. i've now recitified these things.

So now my charging system has a brand new battery, a used R6 reg/rec with the subframe filed flat and thermo grease applied to the back of the reg rec to help dissepate heat. and once it arrives, some used but tested and working windings so essentially a refresh of the whole charging system. i've cleaned up the earth connections (although they looked like new to be fair) so hopefully this should all put me right.

Is red rubber grease the same a silicone grease? If so i've got loads of this so i will use that to coat my battery terminals, otherwise i have some of the thermo grease left over- is that suitable?

Silicon grease is more or less the same as the next type, the red one just has a dye in it to help identify it, I think.