Broken down with a dead battery

[garynortheast]

I can report that I now have a fully functioning charging system again. Just took the bike into Welshpool and back it's all working a treat.

[Craig380]

Good stuff. Few things are more annoying than a niggling fault, and few things more satisfying than solving it.

[garynortheast]

Well now, it looks like I have a reg/rec problem again.

Bike kept stalling when I was stopping at junctions. Turn off the lights and it runs a little while longer before dying. Got home and there's not enough charge to start the bike.

Currently got the battery on charge, when it has enough to start the engine I'll run some tests.

Reg/rec was a mosfet type from Electrex World and only fitted last October, so still within warranty. If it's faulty I'll request a replacement. I'm hoping it's not the alternator.....

[garynortheast]

Hmmm. The battery has been on charge since about 5.45pm, it's now just coming up to 10pm and it's still not charged. The orange light is still showing on the charger. I'm going to see how it looks in the morning, but I'm wondering if the battery itself is knackered.

I have a couple of good condition spare batteries on the shelf, so if the one on the bike is shot I'll replace it and then check on whether there is a charge going in from the reg/rec.

[garynortheast]

Battery is now showing fully charged so I'll switch off the charger and see if it holds the charge overnight.

[garynortheast]

The charge appears to have held overnight and the battery is showing 13.7 volts with the engine off and no load. Engine on with no load at voltage showed 14.45v. With the lights on that dropped to 13.8 and then after a few seconds started going down, ending at under 13v. Switched of the lights and the voltage then went up to just under 14v but slowly fell again.

I'm going to top up the charge on one of my stored batteries, put that on the bike, and then run the tests again.

[garynortheast]

Thought I'd found the problem there when I was disconnecting the alternator from the reg/rec to do an unregulated test. The wire in the +ve spade in the block connector going from rec/rec to the battery was loose, so I popped the spade out, cleaned it and the exposed end of the wire, then crimped it properly again. Put the block back together and ran the tests again.

@5000rpm with no load - a steady 14.5v at the battery, but with the lights on and at full beam, it gradually drops away to 12.7v @5000rpm.

So now I need to do an unregulated test of the alternator.

[garynortheast]

Right so 3 readings taken between the alternator wires for a no load, unregulated test. All readings broadly similar @5000rpm - 85 - 90v. Book states a min of 60v.

The wiring from alternator to reg/rec is ok as is the wiring from reg/rec to battery. Looks like the reg/rec is on it's way out.

[garynortheast]

Just spoken with Electrex World and they've asked me to send the reg/rec back for testing, so I'll have to get it off the bike and packaged up.

[Craig380]

It's weird that the voltages are fine until you put the lights on. Is the regulator dumping to ground under load, I wonder?