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Post by erbuck on Nov 20, 2019 19:45:36 GMT -6
Apologies if this has already been posted. Search didn't reveal it to me.
Measuring the voltage at the battery for my 454LTD I get the following results:
Key off: 12.85 volts
Engine running at idle: 14 volts
Engine running at 4k RPM : 13.5 volts (plus or minus 0.1 volts)
I"ve looked at the voltage regulator socket and the grounding of the voltage regulator. Cleaned both up to get shiny metal on shiny metal contact. Ground has very good continuity. No change in the voltages observed.
I've checked that the stator wasn't grounding (when the engine is stopped). Zero continuity between stator yellow wires and ground. Stator seems fine.
Question: Is this voltage drop when the engine is revving a feature or a flaw? Anyone seen this before? Am I seeing some voltage leakage at the stator when the engine is revving? Or is this a feature to avoid overcharging the battery during prolonged higher RPM operation?
Thanks for your thoughts.
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Post by Blaine on Nov 21, 2019 6:19:51 GMT -6
Replace your regulator....Its starting to go bad.
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Post by bikeman on Nov 23, 2019 19:55:33 GMT -6
I would keep it on and monitor it, 13.5v is a good enough charge to keep the battery topped up. as Blaine said it may be going bad but could last for years yet.
to put it simply [if you have a stock RR fitted] this type of RR is called a shunt regulator. it works by regulating the AC current from the stator into DC current for the battery. in doing so it also senses the voltage push back from the battery, just after starting or at idle [lights ect on] power is taken from the battery so the level of push back is less typically this will show up as a high charge rate 14+ volts. as the battery charges there is more pushback to the RR so the charge rate drops. however because the stator voltage is more or less constant this means the RR has to get rid of the excess charge it does this by shunting the power to earth producing heat. the more it shunts the more heat there is. this type of RR can get very hot and over time degrade to point where it either stops charging or overcharges the battery boiling it dry.
however this can take a long time usually before this happens the wires in the RR connector will also get hot and burn if the connector is ok then the shunt RR is working but if the charge rate falls or rises a large amount say 3 or 4v then change it. but go for the MOSFET type instead this does not shunt the voltage to earth but has internal switches to turn off the AC power without producing heat so last a lot longer.
as a addon if your RR seems to get hot while running you can fit a 12v computer fan to it this will cool it down and stop it overheating eliminating the issue.
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Post by erbuck on Nov 24, 2019 15:55:30 GMT -6
Thanks for the Input.
Yes, replacements R/Rs are remarkably cheap, so there is little penalty for getting a spare.
However, I agree the 13.5 volts should maintain things, so I'm not in a rush to replace things. I will see if I can borrow a R/R to see if the behavior changes.
In terms of R/R theory, if I understand it correctly, the circuitry within the R/R clips off the sine waves of electricity coming from the stator to get the desired voltage. Is it possible that the 1986 vintage electronics in the R/R is slow enough that it cannot keep up with the faster sine waves of AC created at higher RPM? This is likely something Kawasaki or Shindigen addressed at the time. If this is real, it also provides justification for a newer R/R.
Thanks Again.
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Post by erbuck on Nov 24, 2019 16:31:18 GMT -6
OK, update when I read an interesting article on another board. It is speaking of the benefits of MOSFET voltage regulators over (OEM) Shunt style regulators. I'm not ready to run out and buy a MOSFET R/R, but it seems pretty easy to wire one up.
The quote of interest is: In testing, you can immediately see the difference - regardless of the engine rpm, the output voltage remains constant. This shows that it is a TRUE regulator vs the crude SCR shunt of the OEM. Typical behaviour on the OEM SCR R/R is that the voltage will actually decrease as rpm increases - this seems counter-intuitive to many peoples logical thought, but it is because the R/R is actually sinking more as the generated voltage increase.
The full article is linked here as the author should be credited:
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Post by bikeman on Nov 24, 2019 17:17:57 GMT -6
hi. TBH the circuitry is quite complex depending on the system used. the 454 and other old bikes use basically the same system.
in the generator stator/flywheel power is produced by spinning magnets around a coil of wire. [much the same as an electric motor except the magnets are permanent and not energised by introducing electric] this induces a current down the wires. but because there are two poles to each magnet the power produced is AC because as the north pole passes it makes a positive charge but when the south pole passes it makes a negative charge. but both go out through the same wires.
think of AC current like a sinewave with up and down troughs these go to the RR [rectifier/regulator] which has two separate parts in the rectifier the current enters with equal parts of + and - charge the bike only needs the positive charge so basically ignores or switches the - part off so only the positive charge gets through. this turns the current into DC voltage. but of course because the revolution of the generator changes through the rev range of the bike. the now DC current is way too high to run the bikes 12v systems and charge the battery. by the way all RR's are the same upto this point.
the difference is in the second function the regulator. the older regulators choke down the voltage to a acceptable level and allow the excess voltage to be bypassed or wasted to earth the term for this is shunting or a shunt type regulator, this process produces heat the more it shunts the more heat is produced. the heat is dispersed by the cooling fins on the unit and the unit being placed in a position with direct airflow over it.
the newer Mosfet RR's have micro switches instead of chokes and act like turning a light switch on /off so little heat is produced in the process that's why they will last a life time of use. when you can see how the different types operate it is easy to understand the issues. more heat more prone to bunt out plus choking the voltage is not as reliable as switching some of it off but yet being able to switch it back on if needed. so a more stable charge for the battery at any rev range.
hope this helps somewhat. .
Ps, read the thread yeah basically what I said in more detail. as a quick addon though any mosfet with the 3wire stator leads will work you have to be handy at wiring but not difficult. some of the used ones " there isn't much point in buying new as they never wear out" can be bought very cheap on fleabay probably cheaper than a used stock unit. and yes before anyone asked I have mosfets on both my bikes.
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