Intermittent charging issue

Probably know the answer already, but querying anyone good with electrics.

I had a R/R go duff on the hornet last year, and replaced with a MOSFET unit from an R1. Since then I've had pretty much no issues. However, my Oxford heated grips have a battery cutout feature which means if the battery drops below something like 11.8v a green light flashes and they cut the power.

Recently that happened a few times for a few minutes each time. Last night they were fairly bad, so when I got back I put a multimeter on it and discovered the battery at low voltage and not charging properly (about 12.2v). I checked all the connections to the R/R (easily accessible), and the connector between the stator and the R/R, all seemed okay, but cleaned the connections and put back together. Bike starts, battery at 12.8v idle with lights + grips on, rising to about 13.5v. All good, I thought.

Today on the way to work the low battery flashing light came on and stayed on. I managed to get the bike home tonight, but by the time I was back, the battery was too weak to turn the engine over, showing 11.3v.

After charging it back up, the bike was charging low again. Bugger, I thought. In the process of checking around, I discovered that everything seemed in tolerance according to the Honda manual. In frustration, I was going to check to see if there was a current leak anywhere, when I discovered the battery earth nut had stripped its threads and was loose. Replacement in, checked for good contacts, charged battery, R/R now showing an output of 13.5v rising to 14v. All good.

Here's my query:

After doing all this, I decided I'd just try to rule out anything else that may be intermittent, and decided to check the stator output. Bearing in mind the R/R is now outputting 13.5v-14v, I'm unsure what to make of this.

Resistance is all in spec for it. However, the output between each phase seems to be 9V ac, rising to about 13V ac at 5krpm. Output between each phase and ground is about 14-16V ac.

Now, I'm fairly sure I remember that the output should be 20-70Vac. Is this right? If so, is the stator shot? If so, how is the R/R outputting the correct voltage?

Stator should push out 70ac at 6k and above. The battery may have been knackered with the constant drain and recharge and the cells internal blades can seperate under heat(charge) breaking the circuit. You shouldn't have any connectivity but ground and stator or ground and the R/R. Check out the guides on electrosport.com and Dansmc.com
Source:2 months VOR tracing blown stator & R/R

[Sid Squid]

What bike have you got?

This will help.

Originally Posted by Sid Squid

What bike have you got?

This will help.

Originally Posted by Neeja

I had a R/R go duff on the hornet last year, and replaced with a MOSFET unit

However, seems all is well anyway.

Turns out the ponderous electrical problem was a duff multimeter that won't read AC properly. Another multimeter confirms that the stator is outputting 16VAC when the engine is cold (and idling below 1krpm), rising to 45VAC at 3Krpm and 60VAC at 5Krpm. Didn't want to test higher this morning as it was early and would annoy the neighbours, but I'm getting good figures all over.

When fiddling around the battery suddenly stopped charging. Wiggling wires confirmed that the earth spade connector to the R/R wasn't great, so I resoldered it. As a result, system voltage is now 13.6V at idle with only lights and 13.2V with lights and heated grips at 100%, and any engine speed above 3Krpm has it sitting at a solid 14.2V.

Seems solved for now - but I'll test next week to see if anything breaks down when the bike is hot.

Working well then. I was going to suggest earth connections (seen this recently on a CBR where the frame/engine earth was corroded to hell)
Glad you got it sorted.

C.