I haven't been able to ride my bike (2005 Softail Deluxe) for a while due to work/COVID etc. It's been on a trickle charger for the last 12 months. Bike started fine the other day, I rode it for a few hundred klms, and when I went to restart the bike, the battery was dead. I didn;t notice any issued while riding.

Looks like system was not charging the battery. Since then, I have done the following:

1. Had old battery load tested - battery was shot, so I bought a new battery.

2. Had new battery load tested - came in at 12.8 volts, and was 100%.

3. Installed new battery and tested voltage across battery terminals with bike running at about 2,000rpm - 12.4V, did not increase while raising revs.

4. Unplugged regulator from stator (3 pin system) and checked resistance between all stator pins (1-3, 1-2, and 2-3) - all came in at about 0.1 to 0.2 ohms.

5. Checked each stator pin to ground - all good, with no (infinite) connection on any pin.

6. Started bike and tested stator pins for output AC voltage - each pin putting out around 16-18V at idle, increasing to 26-30V at about 3,000rpm.

All of the above suggests that stator is OK, and problem is with the voltage regulator/rectifier (VR)

7. Bought new VR unit, and installed confirming good connection to stator, and also good ground connection. Also confirmed good connection to master fuse post behind/under rear mudguard.

8. Started bike and tested voltage across battery terminals - still stuck at 12.4V with no increase while raising revs.

9. Disconnected VR output wire (yellow end) from master fuse post, started bike and tested voltage between output wire and earth - confirmed at 14.5-15V.

10. Checked resistance between both posts of master fuse - no resistance/0.1ohms.

11. Checked resistance between master fuse post and battery positive terminal - no resistance/0.1 ohms.

I can't seem to work out why battery is not charging when VR has output of 14.5-15V.

Any assistance would be greatly appreciated.

Cheers,

Harry

Does negative from battery make it to the negative on your reg/rec (either wiring or ground post if that's how ur reg/rec grounds)

As a test of the earths I would run a separate long wire earth from the actual regulator to the battery negative.  That should bypass ALL the various earth cables/points on the bike itself and in theory you should see good high voltages at the battery then.  If so then it definetly points to an earth cable fault somewhere.  OR per the picture the circuit breaker may be buggered on the +ve run - assuming the bike has the same layout (i did not realise there could be a circuit breaker there)

On my FXR there is a separate earth strap UNDER the bike that ties the entire engine/primary/tranny assembly to the frame.  Its a rubber mount engine and so has no electrical connection under normal conditions.   

I had disconnected -ve battery cable and filed down all contact points to the frame and to the battery post before reconnecting.

I had called the circuit breaker in the picture a "master fuse". I believe mine is located under a plastic panel under the rear mudguard.

I have checked it and found no resistance (0.1 ohms) across the 2 posts of the circuit breaker. I will buy a new one anyway and install it.

Thanks again

Scratching my head on this one - Given that there is 14.5V from the VR output wire when it is disconnected and only 12.5V when it is connected to the B post of the circuit breaker, it would seem that there is a short, or earthing, somewhere. I'm not that technically minded but, if that was the case, I would expect that either the bike wouldn't start, or a fuse, including the circuit breaker, would blow. Nothing like that is happening. 

Was thinking to maybe test voltage at +ve lug on starter motor, but I expect it will likely show 12.5 volts (same as battery) because the bike starts fine. 

Might be time to call in an auto-electrician to have a look...

It seems like your stator is on it’s way to permanent retirement!

 Your 2005 Softail should be fitted with the 38amp stator system and produces 18v (VAC) per 1000rpm and 54v(VAC) at 3000rpm.

 With your finding it seems like it’s not producing enough power.At 3000rpm you only have 26-30v(VAC) where it should of been 48-54v(VAC)with the 16-18v(VAC)at idling speed that you have recorded.

 With the figures we have it seems to me that the stator is struggling to produce power...