Voltage readings, before, after...

I never had any R/R issues but I chose to upgrade to the redesigned Honda R/R (31600-MBG-305) for my 1999. I installed the new R/R in June 2008.

When I checked the voltage at the battery, I was a little surprised to find it lower than would seemingly be normal. I did this after I went on vacation for a few weeks and returned to find the bike wouldn't start. Charged the battery fully.

At battery, ignition off = 13.20v
Idle = 13.90v
5000 rpm = 13.25v

I went through the Electrolux troubleshooting procedure and the stator and the R/R checked out fine.

So, I ordered a VFRness and a new Ricks R/R which I intended to keep as an extra.

VFRness installed, Honda R/R

At battery, ignition off = 13.20v
Idle = 14.04v
5000 rpm = 13.65v

Better but a little lower than normal still, right?

VFRness and new Ricks R/R

At battery, ignition off = 13.20v
Idle = 14.45v
5000 rpm = 14.45v

As far as I can tell, these numbers are pretty much perfect and I varied RPM, highbeams, low beams and it stays rock steady.

As everyone else has found, the installation was easy for the VFRness.

All these readings were taken within minutes of each other. Just the installation time in between.

 

I'm new here and no expert, but I'd think a sustained rate of 14.45 would over heat/charge the battery.

I know my fancy $100. home charger keeps the voltage @ 13.65 for months at a time, during the winter time.

 

A properly operating charging system on a VFR or any 12V system for that matter as far as I know should measure 13.5V-14.5V at the battery when the engine is running. This will ensure that the battery is charging appropriately and all of the systems are able to operate without draining the battery. Anything more than around 15V and the regulator is probably having issues. The regulator regulates voltage from the alternator. The AC current produced by the alternator is converted to DC by the rectifier. If the measured voltage drops below 13.5V, my understanding is the regulator will apply current to the field and the alternator starts charging. If the measured voltage exceeds 14.5V, the field is turned off and the current from the alternator will essentially stop.

Bottomline, I believe that 13.5V to 14.5V is the appropriate range for the system.

It's a complex system so I could have some of this misunderstood but these are the assumptions I was working under!

 

The appropriate charge voltage varies with temperature. I don't think the R/R on the VFR does compensate for temperature, however. 14.45Volts may be too high if it's very hot outside. The main thing is you don't want to exceed the voltage that causes the battery to boil, since it's a sealed battery. 14.45 Volts should be good up to about 21 degrees Celcius, according to the table at this link:

How to charge sealed lead acid batteries. Custom battery chargers for OEMs in a hurry from PowerStream

 

Hi I dont know if this is going to help or hinder, I have just bought a Gen 5 with 90000km on the clock two weeks ago. I have been reading on this site about the R/R troubles. So today I pulled out my Multi-meter and manual and got some readings. Here they are : The battery - Off switch = 12.3V, On switch = 11.8V, at idle 12.8V The manual says to have 12.8V off switch (if not, charge the battery which I have done today) An hour ago it was 13.15V I will leave it over night and check if it discharges much). The manual states 12.8V at offswitch, 12V on switch, and 13-14.5V above idle. I had to stop due to the weakness of my battery, but you can then check the current leakeage to the negative terminal and then the rectifier terminals. I jumped ahead pulled off the back fairing and checked out my connections at the R/R. The connectors going to the stator were dark brown compared to the other connectors. I will continue to investigate with a full battery. Hope this helps someone

 

Being the skeptic I am... There are two parts of the equation you're missing here. One is current, the other is the condition of the battery.

Just measuring DCV on the battery terminals is easy, quick and generally definitive as to diagnosing charging problems. However...DCV is a dull and slow reacting tool to measure accurately what is REALLY coming into or going out of your battery. For that you need to measure DC amps...or current flow...in relation to the DCV of the battery AND rpm.

The condition of the battery in terms of capacity, not just the measured DCV determines your charging output. Voltage DROP is the key point here. I've usually found charge rates lower on a battery that has been 'hot' off the charger. Proof of this is your at rest voltage of 13.2...that's a bit high. I suspect if you let the battery sit for a few days you probably would of read more like 12.6. So...as your regulator reads the voltage drop on your battery caused by 'key on' draw and especially the huge draw of the starter motor, it shunts current to or away from your battery.

Guess what I mean is...if you did your tests successively and within minutes. Simply the capacity removed from your battery from lights and starter usage WILL probably elicit a higher output from your charging system. You may not read this with at rest DCV...but you might see it if you measured the voltage drop on your battery while operating the starter motor.

I'm not denying the components you installed might be an improvement. But I'm not sure the test you did is really a valid way of evaluating them.

 

Just an update to my post above... I recently learned that the stock battery is a lead-calcium battery and the charge voltages are a bit higher than your typical automotive battery. So the poster who was getting 14.45 Volts is good to go, there is no risk to the battery.

According to Yuasa (the manufacturer of the stock battery), you should read about 12.8 Volts on a fully charged battery with the switch off. You do need to wait an hour or so, however to get an accurate reading.

 

The battery will always show an inaccurately high value after charging. You should wait overnight for the "surface" charge to disipate. Yep, standard no-load should be around 12.8V.