newtothis wrote:The way that the electrical system runs always strikes me as odd, the generator being maxed out with it's output shorted to earth most of the time just seems wrong. Both the windings and the reg get a hard life, the field effect ones might be a bit more able to cope than the old diode type but essentially they're both getting cooked.
this is simply not true and comes from a general mis-understanding about how shunt type regulators and permanent magnet generators work. i think a lot of downrating shunt type regulators has been done, especially by people selling "upgrades". once you know how a shunt type regulator really alters a permenant magnet genreator then it isnt so strange and doesnt really cuase such a hard time as you first belive.
the bikes system does always move full amps but the actual shunting part doesnt consume as much energy as you think, its not like its always shunting 350 watts of power, the actual shunt value is much smaller (and yes this small shunt draw will generate heat and rob some hp etc but its quite small compared to thining its shunting vast reserve of energy)
this is becuase the permanange magent geneator always shifts the same amount of amps regardless of the voltage, spinning it up only geneates more voltage, unlike the field driven generatos of say a car.
shorting out the mains socket in your house will generate much heat and fire but shorting out the coils in a permananet magnet generator is much less becuase of the design of the system. shoring out the permanent generator alows the power to flow freely back to the generator with very little to no resistance, becuase of this there is no voltage drop and no heat / power genreated like if you stick a screwdriver across the mains of your house.
shunt diodes themselves consume a volt or so of energy and you have sevearl of them so the acutal power disappated during the shutning cycle is probably about 35 - 65 watts, hence the heat.
On this point mosfet is probbaly marginannly better if you want to save a small amount of energy.
The actual reasons for charging system failutre are usually old battery over-stressing the charging system, poor generator to regulator connections causing overload of stator, other wiring connection failures causing system overload.
the acutal shunt design is fine, compared to modern mosfet is may be slightly inferoir, but nothing like a lot of sellers of "upgrade" packages would have you belive.
mosfet will probably be the way to go eventually as its doenst have even as much losses as an scr shutn regulator, but the actual shunt system and permantnent magnet generator is complicated system which many people mistakenly believe that the shunt is always wasting a lot of energy
http://www.apriliaforum.com/forums/show ... regulators
this thread seems to be on the right path