Flat battery.

[trophydave]

So,I get the bike out to ride to work yesterday morning only to find that the battery is completely flat.The bike has only been stood for a couple of days and is usually ridden two or three times a week to work,a fifty mile round trip each time,so plenty of time to charge the battery.Its a Varta battery and is only four months old.I have two Optimate chargers,both work but neither one will bring up a green light on the battery.Straight off charge the battery shows 12.62 volts and starts the bike up fine.At tickover I have 13.4 volts with the lights off and 13.7 with them on.After a few minutes this rises to 14.0 volts.At 3000 rpm I have 13 volts lights off or on and at 5000 rpm 12.3 volts lights off or on.This suggests to me that riding along at about 70mph the battery is not charging.Should the voltage drop like this as the rpms rise?or is the R/R knackered?There is a very small drain on the battery 1.67mA which stops when I remove fuse 3 so I assume that is caused by the clock.The power relay clicks off just after switching off,so,what has caused my battery to go flat?Any suggestions please?

[Bixxer Bob]

Yup, it sounds like either the stator or reg rec is on it's way.  Mine was doing the same before I changed to the Electrex World MOSFET.  If you fancy testing the charging system, go to the Girly How To section and find the link to ... oh never mind, I've done it, here it is...

http://www.electrexworld.co.uk/acatalog/Troubleshooting-3P-PMG-&-RR.pdf

[trophydave]

Thanks Bixxer.I have had another look at it today.The stator is showing continuity between the windings and no leak to earth so I am hoping that is OK.The R/R looked to be OK with a diode check but the values I am getting are higher than those on the Electrexworld fault finder so I think that it is probably that.Also the plugs on the wires to the R/R were getting warm,despite the the terminals being clean.Time for a Mosfet I reckon.

[trophydave]

OK I fitted the Mosfet and Triumph wiring link today.At tickover I now have 14.2 volts that remains pretty steady as the revs rise.However once I put the headlights on the voltage varies between about 13 and 14 volts.The Mosfet only just gets warm unlike the STD R/R that got almost too hot to touch.I have fitted an LED charge indicator light and will try and get out for a ride in the next couple of days to see if that tells me anything.

[Bixxer Bob]

Those numbers are about right, don't forget that, if you have the reg rec with the purple sensing wire , it will only deliver what the battery needs - a bit like a battery tender.  It's good that it's not getting hot, mine runs cool too although I took the precaution of turning it through 90 degrees so the air can flow THROUGH it (obvious when you think about it....  )