Overcharging issue - how is it supposed to work

I have what seems to be a common issue - the charging voltage is too high. There have been a few topics on the subject, some very helpful ones here and another simialr issue here . My issue is related to the first thread - the voltage going into the R/R is too high.

So the issue I have is that there is a voltage drop between the battery and the +12 leading into the regulator/rectifier. It's lost about half a volt, so it's charging about half a volt too high (it charges at about 14.8V in normal conditions). This is a little too high. However, if you turn on the headlights, the accessories voltage drops even lower, so the charging voltage increases even more - well over 15V. That's going to cook my battery.

The thing is though, that's exactly how I would expect this to work. If you have a particular circuit like this, and you start taking out a lot of current (in this case, the headlight, the brake lights, the horn - basically *all* the accessories) there will be a voltage drop. How can the regulator provide a constant charge if the voltage fed into it different depending on which accessories are being used?

I was considering wiring in a relay, such that the accessories circuit will switch open a cable running from the battery to the r/r - so there will be no voltage drop. That will fix the problem, but the current setup must have worked from the factory - it feels like I will be covering up an existing problem instead of fixing it.

So the question is, does the regulator rectifier take the expected voltage drop into consideration? My r/r works at about 14.5 volts, it's just that the voltage drop from the accessories makes it higher. So should it be lower, taking the voltage drop into account, or does my voltage drop too much? Without any load, what voltage should a r/r be running at?

Bad ground or bad regulator.
Steve

The ground is fine - if I run the r/r ground straight to the terminal negative it has no effect.

The regulator might be bad, if 14.5V is bad. It's very consistent at 14.5 volts, but only if I feed the battery voltage directly to the r/r. There is too much voltage drop across the accessories circuit. My question is whether the r/r takes that voltage drop into account - i.e if a bike rolling off the factory floor switched at 14V, (since it was know that the accessories circuit was about 0.5V too low) for an output voltage of 14.5V.

Is it stock or modified? 14.5 is good but if it goes higher, the R/R is bad unless a wire is disconnected.
Steve

The bike is new to me, but everything looks pretty stock. 14.5V is only seen if I short the r/r to the battery terminal though, It seems to be an issue with the voltage drop in the brown wire circuit, but in reality I wouldn't say that a 0.3V drop would be unreasonable (which is what I see when it's running) which bring it up to 14.8V.

As a follow-up, I cleaned all the terminals in the accessories circuit, fuse box and the battery connections and grounding wires, but the charge voltage when the headlight was on was still too high. I also replaced the regulator/rectifier, which made it slightly better but still close to 15V.

I wired in a relay so that the voltage being fed into the regulator/ rectifier was directly from the battery. It now charges at 14.2 volts no matter what revs and accessories used - a more elegant voltage for a more civilised age.