Need help with my charging system

[scutty]

I am having real trouble with the electrical charging system on my bike. the bike runs fine off the battery but as soon as the battery dies then the bike dies. It seems like the bike is just not generating any charge at all.

My battery is showing 13.2v off the bike and shows zero parasitic draw on the bike with the ignition off.

I have tested the alternator windings and they are all showing 0.6 ohms and all coils output approx 60v (AC) at 4000 rpm.

The wiring from the regulator is correct and the diodes all test out correctly.

With the bike running the voltage across the battery is approx 13.8v at idle but drops to 13.6v at 5000rpm and if I disconnect the battery when the bike is running it instantly dies.

Any thoughts?

[micksea]

Try putting a multi meter on the battery terminals and push the start button,if it drops to 8 volts or so then it's got a dead cell.you might recover it with a decent charger

[DaveCon]

Sounds like the rectifier, if the alternator is outputting ok. The only thing keeping the bike going is the battery, which sounds healthy at over 13V
On the bike, with the engine running, the voltage across the terminals is exactly the same as the battery on its own. It should really go up over 14V if the charging system is ok.
Could be a dodgy wire somewhere but from what you've said I would look around the rectifier.

[scutty]

Thanks , I will swap and swap the RR out for another one, hope that solves it.

[bowber]

As Dave said it should be around 14v while running.
It could also be a winding burnt out, sometimes they are hard to measure with normal electrical test gear. Swap your R/R as that's easy to do, if no change then I'd suspect a burnt out winding.
If it is I think there are a few good rewind companies that do it for a reasonable price.

Steve

[scutty]

Thanks Steve

I actually measured the alternator output while running at approx 60Vac on each winding so they looks really spot on. I'll post back if I get results from changing the RR

[scutty]

Thanks for all help, turns out my regulator is fried. I put a new one on last night and everything is working!