X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from n7.bullet.re3.yahoo.com ([68.142.237.92] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with SMTP id 3556156 for flyrotary@lancaironline.net; Mon, 23 Mar 2009 08:44:55 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.237.92; envelope-from=casey.gary@yahoo.com Received: from [68.142.237.90] by n7.bullet.re3.yahoo.com with NNFMP; 23 Mar 2009 12:44:19 -0000 Received: from [216.252.111.169] by t6.bullet.re3.yahoo.com with NNFMP; 23 Mar 2009 12:44:19 -0000 Received: from [127.0.0.1] by omp104.mail.re3.yahoo.com with NNFMP; 23 Mar 2009 12:44:19 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 422436.27908.bm@omp104.mail.re3.yahoo.com Received: (qmail 29676 invoked by uid 60001); 23 Mar 2009 12:44:19 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1237812259; bh=Zvc4ey/9QbQdp9a0o0866tbgPlbudVXoe8cHmN0Dkg0=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=a5MTZ7LcQ3wvdU1MC0HiOj2u5YyhIU5KfI8GwRCf5jo5RMtlFtcZrU5PQDqYsRkoG9umq9ekvLWvKaWLwaWQJGRWoupcNoThYhZQ7kUzUvDbMkV1BQKFLJRoIE+WKWPoV8UTNaPmS/Rzu0kVE1isjhdX+3mFSnLJnYdxZGJhn/g= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=H7FRu1mRNg/q4WDVhpYbltMRbkpfgFzInUY5WTVRwmCBKB3Vi9wF7BD97m4BTQE//cDMa1HcLsF+qgkUMyAd/bjpdOv8Z26FfB71Pkto9RY1UZKr+E/GV36Ru2wPhNItNGBxFfIwAy9GoqFZEeDtyyfy9PLPHD/YFe2+A2o6u9s=; Message-ID: <192495.26683.qm@web57515.mail.re1.yahoo.com> X-YMail-OSG: 3VWlbuQVM1lIbC537yQrGcjbdaR3.OaFpB_X1O.IA1801ejPg1haiPh7Pg5Dj5VATyrUUKnWr1G3.DNHmyoF9vtiRS8a2Dbf3.qlGdZWbbup3kg0.xr_aPlZCO1v5O5vgvTCi2VtIt5dE.5vY28fSHmOcXaJUeGtQRNUzYDiZmy4rvOES3yeHGBNoEPa4vlQrYxRqNH9RlI5erl3e2X73oIPIBE- Received: from [97.122.186.190] by web57515.mail.re1.yahoo.com via HTTP; Mon, 23 Mar 2009 05:44:18 PDT X-Mailer: YahooMailRC/1277.32 YahooMailWebService/0.7.289.1 References: Date: Mon, 23 Mar 2009 05:44:18 -0700 (PDT) From: Gary Casey Subject: Re: Alternator (Off topic To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-795322055-1237812258=:26683" --0-795322055-1237812258=:26683 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable This discussion on alternators is interesting. First, I'll have to disagre= e with Bill B about the alternator "load" with the engine not running. The= voltage capability of the alternator is proportional to rpm and at crankin= g speed it will not be able to deliver battery voltage and therefore its ou= tput will be zero and therefore the power to turn it will be no more than t= he friction in the bearings. The field will, of course, be full on, which = will result in a battery drain of about 3 amps. Compared to the starter dr= aw of maybe 200 amps it is trivial. Some people leave the alternator off t= o save that current, but there isn't much incentive to do that. The only r= eal reason to ever turn the master on without the alternator is if you don'= t intend to start the engine (maintenance, setting the radios, or whatever)= - then there will be less draw on the battery.=0A=0AThe second post by Tom= is partly true - most voltage regulators are "switching" regulators in tha= t the field is either turned on or off. But the battery only partially smo= othes the output. The main reason this works is that the alternator field = windings (in the armature) have a very high inductance and a "free-wheeling= " or "clamping" diode is placed across the field. When the regulator turns= off current continues to flow through the field, driven by the inductance = of the field itself. This is easiest to visualize by drawing the field coi= l with a diode connecting the top and bottom (ground terminal). Shut off t= he supply and pretend that the coil is a big flywheel and the current doesn= 't want to stop - it will flow through the diode from the ground to the top= (supply) end, which is now at a slightly negative voltage. The alternator= output will decrease gradually (well, in milliseconds) until the system vo= ltage drops below the threshold set in the regulator, whereupon the regulator will turn full on again, bumping it bac= k up. Imagine a bicycle wheel that you just have to hit now and then to ke= ep it turning - or read Jim's explanation. The big advantage of this is th= at the regulator is either full on or full off and therefore will dissipate= very little heat. The disadvantage is that electrical noise will generate= d by the switching, but that noise is generally not a problem for any other= electrical device. There are some regulators (B&C for example) that are "= linear" and they actually regulate a continuous current in the field and th= e manufacturers of these claim that their system is "quieter." They will, = however, draw more continuous current will run hotter, requiring some sort = of cooling fins or something. Are they worth the extra cost? I doubt it, = but I have one that was acquired as part of the system.=0A=0AI believe Tom'= s idea of turning on all the electrical loads in a car to test the battery = is that the alternator is typically incapable of supplying that load at idl= e speed and therefore the battery voltage will drop enough to cause the eng= ine electronics to stop working, "killing" the engine. Problem is that all= current automotive systems will continue to work down to less than 6 volts= .. The battery would have to be virtually gone to drop that low. Gone far = enough that it probably couldn't crank the engine.=0A=0AFinally, Mike has a= question on alternator "noise." This is generally caused by the high-freq= uency pulses of current produced by the alternator stator windings. All di= odes have finite response time and when "hit" with a sudden pulse there wil= l be a slight delay before they start conducting. This produces a sharp vo= ltage spike in the windings and this will propagate throughout the electric= al system of the plane. If you put a scope on the main power line you will= see this characteristic if you look close enough. The voltage spikes will= be small and very short - maybe one microsecond - but they are there. The= repetition rate of these is such that it is in the audible frequency range= and therefore can sometimes be heard in the audio system. (as I recall, a= typical alternator puts out something like 14 pulses per rev and it turns = at about 2.5 times engine speed, which is 583 Hz at 1,000 rpm. The best wa= y to kill this noise is to use a "feed-thru capacitor" in the alternator output line. I'll take that back - the BEST = way is to buy components that aren't sensitive to the noise, but how do you= know that until you've already spent the money. Feed-thru caps with the r= equired capacity are typically metal cylinders about an inch long with a he= avy wire going into each end and a mounting tab on the side. The mouting t= ab is important - that's the path that conducts the noise to ground. It's = best to mount the cap directly to the noise source - the alternator - and t= he next best is to the engine. Also, you should check all the connections = in the high current path. Maybe run a ground wire from the alternator grou= nd terminal to the engine (I know, the alternator is already bolted to the = engine, but do it anyway).=0A=0AGary Casey=0A=0A=0A-----Inline Message Foll= ows-----=0A=0A=0AThis is why you should not turn your alternator on until a= fter the=0Aengine starts. The alternator loads will almost double the load= on the=0Astarter. The voltage regulator will call for maximum output from= the=0Aalternator while the starter is cranking. For a 60A alternator this= is=0Aabout 720 watts. Darn near 1 HP! In cars, the alternator is=0Aautom= atically put to sleep during starting by the ignition switch. In=0Aplanes,= it is up to us.=0A =0ABill B=0A =0A =0A=0AThe field is either on or off. = =0A=0AThe regulator would create too much heat with a linear function, so = solution is just a 'switch' function in the regulator IC.=0A=0ABattery does= the trick in smoothing the voltage.=0A=0AGeorge -- simple test is with the= engine idling, kick on the lights/fan... note the rpm drop.=0AThat is the = load of the alternator turning on. Newer vehicles will have additional inpu= ts to the alternator so it knows when the AC is on, or when you kick WOT (w= ide open throttle) as it will disconnect the alternator and A/C off for a b= rief amount of time. Also a simple battery test is to (in the car) kick = on all loads at idle.... if the engine dies, battery reserve isn't there an= d time to replace 'em. =0A=0ATom=0A=0A=0A =0AHowever, by switching the fi= eld on and off at a fairly fast rate and varying the pulse=0Awidth duration= of the field current, a linear approximation can be achieved with a consta= nt voltage as the result, within the limits of the system of course.=0AThat= is in essence how the voltage regulator achieves its function.=0A =0AJim= =0A=0A=0ASlightly off topic, but does anyone have a =0Asuggestion for an of= f the shelf filter to kill/reduce alternator electrical =0Anoise? I have an= alternator off of a Geo Metro/Chevy Sprint with internal =0Aregulator. I h= ave a switch on the panel to energize the field. After the engine =0Ais run= ning and I switch on the alternator I get a noticeable hum in the =0Ainterc= om. This is one of those nagging little issues I havent gotten around to = =0Afixing yet since first flight. =0A =0A Also in a previous thread someone= (maybe Al =0AG.?) mentioned an over-voltage protection device for the alte= rnator output that =0Awould be compatible with the internally regulated alt= ernator. I'd like to =0Aadd something like that as well - suggested sources= ?=0A =0AThanks,=0A =0AMike Wills=0ARV-4 N144MW=0A----- Original Message ---= -- =0AFrom: James Maher =0ATo: Rotary motors in aircraft =0ASent: Sunday, M= arch 22, 2009 7:45 =0AAM=0ASubject: [FlyRotary] Re: Alternator (Off topic)= =0A=0ATom,=0AYou are right, of coarse, about the alternator field being ei= ther on or off.=0AI may have implied that the field current was a linear fu= nction but I was only trying to=0Asimplify the explanation.=0A =0AHowever,= by switching the field on and off at a fairly fast rate and varying the p= ulse=0Awidth duration of the field current, a linear approximation can be = achieved with a constant voltage as the result, within the limits of the s= ystem of course.=0AThat is in essence how the voltage regulator achieves it= s function.=0A =0AAs for your "simple test" it may not give the expected r= esults, as most modern car engines, those that are controlled by computers= , will have the idle speed determined by the computer as well.=0ASo increa= sing the load at idle, either mechanical or electrical, will cause the=0Ac= omputer to sense a decrease in RPM and if it goes below a predetermined va= lue the computer will open the throttle (or idle speed valve) to increase = the RPM to the correct idle speed.=0A =0AJim=0A--- On Sun, 3/22/09, thomas = walter wrote:=0A=0AFrom: thomas walter =0ASubject: [FlyRotary] Re: Alternator (Off topic)=0ATo: "Ro= tary motors in aircraft" =0ADate: Sunday, Mar= ch 22, 2009, 10:03 AM=0A=0A=0AJim,=0A=0AThe field is either on or off. = =0A=0AThe regulator would create too much heat with a linear function, so = solution is just a 'switch' function in the regulator IC.=0A=0ABattery doe= s the trick in smoothing the voltage.=0A=0AGeorge -- simple test is with t= he engine idling, kick on the lights/fan... note the rpm drop.=0AThat is t= he load of the alternator turning on. Newer vehicles will have additional= inputs to the alternator so it knows when the AC is on, or when you kick = WOT (wide open throttle) as it will disconnect the alternator and A/C off = for a brief amount of time. Also a simple battery test is to (in the c= ar) kick on all loads at idle.... if the engine dies, battery reserve isn'= t there and time to replace 'em. =0A=0ATom=0A=0A=0A=0A=0A=0A=0A=0A1) Re: = Alternator (Off topic)=0A by James Maher =0A=0A=0AGe= orge,=0AI'm sorry to disagree with you but you are quite mistaken in your = belief about the=0Aalternator function.=0AThe alternator output is mostly a= function of load because of the voltage regulator,=0Awhose function is to= keep the voltage constant with changes in load and RPM.=0AIt performs thi= s function by varying the field current in the alternator.=0AIf fact this = is one of the many advantages of the alternator over a generator.=0AThe al= ternator's voltage output is also more or less constant regardless of engi= ne RPM, also due to the regulator's function.=0AYou said "The alternator c= harges the battery - which in turn runs the accessories".=0AThis is not ex= actly true. If the battery voltage is below that of the alternator output= =0Athen yes the alternator will function to charge the battery, however if= the battery is fully charged then the alternator will not be charging the= battery but will provide the necessary power to drive any other loads con= nected to the system.=0ASo reducing the electrical load on the system will= indeed reduce the mechanical load on=0Athe engine thereby using less over= all energy.=0AHope this clarifies your misconception.=0ADon't feel bad, man= y people do not fully understand even the most simple of electrical device= s and the alternator/regulator charging system is fairly complex.Jim=0A= =0A =0A =0A=0A-----Inline Message Follows-----=0A=0AWith the fuel injected = rotaries we are dependent on a good source of=0Apower to run the computer a= nd fuel pumps. I used the information on=0Athe AeroElectric list to design= my wiring. http://www.matronics.com/Navigator?AeroElectric-List They = have=0Ainformation on what and where to get over-voltage controllers. Whey= =0Aalso have several wiring diagrams for "all electric" aircraft. These=0A= include ways to feed the Critical Buss through several=0Adifferent independ= ent paths so one failure does not turn you into a=0Aglider.=0A=0ADennis Hav= erlah=0A=0A=0AMike Wills wrote: =0ASlightly off topic, but does anyone=0Aha= ve a suggestion for an off the shelf filter to kill/reduce alternator=0Aele= ctrical noise? I have an alternator off of a Geo Metro/Chevy Sprint=0Awith = internal regulator. I have a switch on the panel to energize the=0Afield. A= fter the engine is running and I switch on the alternator I get=0Aa noticea= ble hum in the intercom. This is one of those nagging little=0Aissues I hav= ent gotten around to fixing yet since first flight.=0A =0A Also in a previo= us thread someone=0A(maybe Al G.?) mentioned an over-voltage protection dev= ice for the=0Aalternator output that would be compatible with the internall= y=0Aregulated alternator. I'd like to add something like that as well -=0As= uggested sources?=0A =0AThanks,=0A =0AMike Wills=0ARV-4 N144MW=0A-----=0AOr= iginal Message ----- =0AFrom: James=0AMaher =0ATo: Rotary motors in aircraf= t =0ASent: Sunday, March 22, 2009 7:45 AM=0ASubject: [FlyRotary] Re: Altern= ator (Off topic)=0A=0ATom,=0AYou are right, of coarse, about the alternator= field=0Abeing either on or off.=0AI may have implied that the field curren= t was a linear=0Afunction but I was only trying to=0Asimplify the explanati= on.=0A =0AHowever, by switching the field on and off at a fairly=0Afast rat= e and varying the pulse=0Awidth duration of the field current, a linear=0Aa= pproximation can be achieved with a constant voltage as the result,=0Awithi= n the limits of the system of course.=0AThat is in essence how the voltage = regulator achieves=0Aits function.=0A =0AAs for your "simple test" it may n= ot give the expected=0Aresults, as most modern car engines, those that are = controlled by=0Acomputers, will have the idle speed determined by the compu= ter as well.=0ASo increasing the load at idle, either mechanical or=0Aelect= rical, will cause the=0Acomputer to sense a decrease in RPM and if it goes = below=0Aa predetermined value the computer will open the throttle (or idle= =0Aspeed valve) to increase the RPM to the correct idle speed.=0A =0AJim=0A= --- On Sun, 3/22/09, thomas walter wrote:=0A=0AFro= m:=0Athomas walter =0ASubject: [FlyRotary] Re: Alte= rnator (Off topic)=0ATo: "Rotary motors in aircraft" =0ADate: Sunday, March 22, 2009, 10:03 AM=0A=0A=0AJim,=0A=0AThe fiel= d is either on or off. =0A=0AThe regulator would create too much heat with= a linear function, so=0Asolution is just a 'switch' function in the regula= tor IC.=0A=0ABattery does the trick in smoothing the voltage.=0A=0AGeorge -= - simple test is with the engine idling, kick on the=0Alights/fan... note t= he rpm drop.=0AThat is the load of the alternator turning on. Newer vehicle= s will have=0Aadditional inputs to the alternator so it knows when the AC i= s on, or=0Awhen you kick WOT (wide open throttle) as it will disconnect the= =0Aalternator and A/C off for a brief amount of time. Also a simple=0Aba= ttery test is to (in the car) kick on all loads at idle.... if the=0Aengine= dies, battery reserve isn't there and time to replace 'em. =0A=0ATom=0A= =0A=0A=0A=0A=0A=0A=0A1) Re: Alternator (Off topic)=0A by James Maher =0A=0A=0AGeorge,=0AI'm sorry to disagree with you but you a= re=0Aquite mistaken in your belief about the=0Aalternator function.=0AThe a= lternator output is mostly a function of=0Aload because of the voltage regu= lator,=0Awhose function is to keep the voltage constant=0Awith changes in l= oad and RPM.=0AIt performs this function by varying the field=0Acurrent in = the alternator.=0AIf fact this is one of the many advantages of=0Athe alter= nator over a generator.=0AThe alternator's voltage output is also more=0Aor= less constant regardless of engine RPM, also due to the regulator's=0Afunc= tion.=0AYou said "The alternator charges the battery -=0Awhich in turn runs= the accessories".=0AThis is not exactly true. If the battery=0Avoltage is = below that of the alternator output=0Athen yes the alternator will function= to=0Acharge the battery, however if the battery is fully charged then the= =0Aalternator will not be charging the battery but will provide the=0Aneces= sary power to drive any other loads connected to the system.=0ASo reducing = the electrical load on the system=0Awill indeed reduce the mechanical load = on=0Athe engine thereby using less overall energy.=0AHope this clarifies yo= ur misconception.=0ADon't feel bad, many people do not fully=0Aunderstand e= ven the most simple of electrical devices and the=0Aalternator/regulator ch= arging system is fairly complex.=0AJim=0A=0A =0A =0A=0A-----Inline Message = Follows-----=0A=0A=0AMike;=0A =0AThe first thing to try is a large=0Acapaci= tor at the alternator between the B terminal (output) and grnd (the case).= =0ATry about 10,000 microFarad in an electrolytic type. Be aware of polarit= y to=0Aconnect it right.=0A =0AThe over-voltage (crowbar circuit) that=0AI = have I got from Aeroelectric Connection. I don=E2=80=99t think he sells=0A= stuff directly anymore but maybe you can get it from B&C. Connects=0Aacros= s the field supply circuit breaker, and fails to short above something=0Ali= ke 17-18 volts (IIRC) =E2=80=93 tripping the breaker.=0A =0ADon=E2=80=99t k= now about yours; but normally=0Aautomotive alternators with internal regula= tors feed the current to the field=0Ainternally directly from the regulator= .. The small excitation current=0Arequired to get things started comes thro= ugh the =E2=80=98idiot=E2=80=99 light circuit=0A(one of the terminals on th= e alt). Over-voltage protection on that=0Acircuit won=E2=80=99t do anythin= g. On my Mitsubishi alternator, I took it=0Aapart and undid the internal c= onnection. I learned about this from an=0Aarticle in Contact! years ago (I= ssue 46, Sept 1998). Maybe you can find a=0Acircuit diagram for your altern= ator; or maybe it is made by Mitsubishi or Nippondenso,=0Aboth of which are= covered in the article. I can provide a copy if that=0Ahelps.=0A =0ABest,= =0A =0AAl=0A =0A =0A-----Original Message-----=0AFrom: Rotary motors in air= craft=0A[mailto:flyrotary@lancaironline.net] On=0ABehalf Of Mike Wills=0ASe= nt: Sunday, March 22, 20097:37 AM=0ATo: Rotary motors in aircraft=0ASubject= : [FlyRotary] Re:=0AAlternator (Off topic)=0A =0ASlightly off topic, but do= es anyone=0Ahave a suggestion for an off the shelf filter to kill/reduce al= ternator=0Aelectrical noise? I have an alternator off of a Geo Metro/Chevy = Sprint with=0Ainternal regulator. I have a switch on the panel to energize = the field. After=0Athe engine is running and I switch on the alternator I g= et a noticeable hum in=0Athe intercom. This is one of those nagging little = issues I havent gotten around=0Ato fixing yet since first flight.=0A =0A Al= so in a previous thread=0Asomeone (maybe Al G.?) mentioned an over-voltage = protection device for the=0Aalternator output that would be compatible with= the internally regulated=0Aalternator. I'd like to add something like that= as well - suggested=0Asources?=0A =0AThanks,=0A =0AMike Wills=0ARV-4 N144M= W=0A----- Original Message ----- =0AFrom:James Maher =0ATo:Rotary=0Amotors = in aircraft =0ASent:Sunday,=0AMarch 22, 2009 7:45 AM=0ASubject:[FlyRotary]= =0ARe: Alternator (Off topic)=0A =0ATom,=0AYou are right, of coarse, about = the alternator field being either on or off.=0AI may have implied that the = field current was a linear function but I was only trying to=0Asimplify the= explanation.=0A =0AHowever, by switching the field on and off at a fairly = fast rate and varying the pulse=0Awidth duration of the field current, a li= near approximation can be achieved with a constant voltage as the result, w= ithin the limits of the system of course.=0AThat is in essence how the volt= age regulator achieves its function.=0A =0AAs for your "simple test" it may= not give the expected results, as most modern car engines, those that are = controlled by computers, will have the idle speed determined by the compute= r as well.=0ASo increasing the load at idle, either mechanical or electrica= l, will cause the=0Acomputer to sense a decrease in RPM and if it goes belo= w a predetermined value the computer will open the throttle (or idle speed = valve) to increase the RPM to the correct idle speed.=0A =0AJim=0A--- On Su= n, 3/22/09, thomas walter wrote:=0AFrom: thomas wa= lter =0ASubject: [FlyRotary] Re: Alternator (Off to= pic)=0ATo: "Rotary motors in aircraft" =0ADate= : Sunday, March 22, 2009, 10:03 AM=0AJim,=0A=0AThe field is either on or of= f. =0A=0AThe regulator would create too much heat with a linear function, = so solution is just a 'switch' function in the regulator IC.=0A=0ABattery d= oes the trick in smoothing the voltage.=0A=0AGeorge -- simple test is with = the engine idling, kick on the lights/fan... note the rpm drop.=0AThat is t= he load of the alternator turning on. Newer vehicles will have additional i= nputs to the alternator so it knows when the AC is on, or when you kick WOT= (wide open throttle) as it will disconnect the alternator and A/C off for = a brief amount of time. Also a simple battery test is to (in the car) ki= ck on all loads at idle.... if the engine dies, battery reserve isn't there= and time to replace 'em. =0A=0ATom=0A=0A=0A=0A=0A=0A=0A1) Re: Alternator= (Off topic)=0A by James Maher =0AGeorge,=0AI'm sorry= to disagree with you but you are quite mistaken in your belief about the= =0Aalternator function.=0AThe alternator output is mostly a function of loa= d because of the voltage regulator,=0Awhose function is to keep the voltage= constant with changes in load and RPM.=0AIt performs this function by vary= ing the field current in the alternator.=0AIf fact this is one of the many = advantages of the alternator over a generator.=0AThe alternator's voltage o= utput is also more or less constant regardless of engine RPM, also due to t= he regulator's function.=0AYou said "The alternator charges the battery - w= hich in turn runs the accessories".=0AThis is not exactly true. If the batt= ery voltage is below that of the alternator output=0Athen yes the alternato= r will function to charge the battery, however if the battery is fully char= ged then the alternator will not be charging the battery but will provide t= he necessary power to drive any other loads connected to the system.=0ASo r= educing the electrical load on the system will indeed reduce the mechanical= load on=0Athe engine thereby using less overall energy.=0AHope this clarif= ies your misconception.=0ADon't feel bad, many people do not fully understa= nd even the most simple of electrical devices and the alternator/regulator = charging system is fairly complex.=0AJim=0A =0A =0A=0A-----Inline Message= Follows-----=0A=0A=0A --0-795322055-1237812258=:26683 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
This discussion on alternators is interesting. =C2= =A0First, I'll have to disagree with Bill B about the alternator "load" wit= h the engine not running. =C2=A0The voltage capability of the alternator is= proportional to rpm and at cranking speed it will not be able to deliver b= attery voltage and therefore its output will be zero and therefore the powe= r to turn it will be no more than the friction in the bearings. =C2=A0The f= ield will, of course, be full on, which will result in a battery drain of a= bout 3 amps. =C2=A0Compared to the starter draw of maybe 200 amps it is tri= vial. =C2=A0Some people leave the alternator off to save that current, but = there isn't much incentive to do that. =C2=A0The only real reason to ever t= urn the master on without the alternator is if you don't intend to start th= e engine (maintenance, setting the radios, or whatever) - then there will be less d= raw on the battery.

The second post by Tom is part= ly true - most voltage regulators are "switching" regulators in that the fi= eld is either turned on or off. =C2=A0But the battery only partially smooth= es the output. =C2=A0The main reason this works is that the alternator fiel= d windings (in the armature) have a very high inductance and a "free-wheeli= ng" or "clamping" diode is placed across the field. =C2=A0When the regulato= r turns off current continues to flow through the field, driven by the indu= ctance of the field itself. =C2=A0This is easiest to visualize by drawing t= he field coil with a diode connecting the top and bottom (ground terminal).= =C2=A0Shut off the supply and pretend that the coil is a big flywheel and = the current doesn't want to stop - it will flow through the diode from the = ground to the top (supply) end, which is now at a slightly negative voltage= .. =C2=A0The alternator output will decrease gradually (well, in milliseconds) until th= e system voltage drops below the threshold set in the regulator, whereupon = the regulator will turn full on again, bumping it back up. =C2=A0Imagine a = bicycle wheel that you just have to hit now and then to keep it turning - o= r read Jim's explanation. =C2=A0The big advantage of this is that the regul= ator is either full on or full off and therefore will dissipate very little= heat. =C2=A0The disadvantage is that electrical noise will generated by th= e switching, but that noise is generally not a problem for any other electr= ical device. =C2=A0There are some regulators (B&C for example) that are= "linear" and they actually regulate a continuous current in the field and = the manufacturers of these claim that their system is "quieter." =C2=A0They= will, however, draw more continuous current will run hotter, requiring som= e sort of cooling fins or something. =C2=A0Are they worth the extra cost? = =C2=A0I doubt it, but I have one that was acquired as part of the system.

I believe Tom's idea of turning on all the electrical loads in a car to = test the battery is that the alternator is typically incapable of supplying= that load at idle speed and therefore the battery voltage will drop enough= to cause the engine electronics to stop working, "killing" the engine. =C2= =A0Problem is that all current automotive systems will continue to work dow= n to less than 6 volts. =C2=A0The battery would have to be virtually gone t= o drop that low. =C2=A0Gone far enough that it probably couldn't crank the = engine.

Finally, Mike has a question on alternator= "noise." =C2=A0This is generally caused by the high-frequency pulses of cu= rrent produced by the alternator stator windings. =C2=A0All diodes have fin= ite response time and when "hit" with a sudden pulse there will be a slight= delay before they start conducting. =C2=A0This produces a sharp voltage sp= ike in the windings and this will propagate throughout the electrical system of the p= lane. =C2=A0If you put a scope on the main power line you will see this cha= racteristic if you look close enough. =C2=A0The voltage spikes will be smal= l and very short - maybe one microsecond - but they are there. =C2=A0The re= petition rate of these is such that it is in the audible frequency range an= d therefore can sometimes be heard in the audio system. =C2=A0(as I recall,= a typical alternator puts out something like 14 pulses per rev and it turn= s at about 2.5 times engine speed, which is 583 Hz at 1,000 rpm. =C2=A0The = best way to kill this noise is to use a "feed-thru capacitor" in the altern= ator output line. =C2=A0I'll take that back - the BEST way is to buy compon= ents that aren't sensitive to the noise, but how do you know that until you= 've already spent the money. =C2=A0Feed-thru caps with the required capacit= y are typically metal cylinders about an inch long with a heavy wire going = into each end and a mounting tab on the side. =C2=A0The mouting tab is important - that's the = path that conducts the noise to ground. =C2=A0It's best to mount the cap di= rectly to the noise source - the alternator - and the next best is to the e= ngine. =C2=A0Also, you should check all the connections in the high current= path. =C2=A0Maybe run a ground wire from the alternator ground terminal to= the engine (I know, the alternator is already bolted to the engine, but do= it anyway).

Gary Casey


-----Inline Message Follows-----
=0A=0A=0A =0A =0A=0A =0A=0A=0A=0A=0A=0A=0A=0A
= =0A=0A
=0A=0A

This is why you should not turn yo= ur alternator on until after the=0Aengine starts.=C2=A0 The alternator load= s will almost double the load on the=0Astarter.=C2=A0 The voltage regulator= will call for maximum output from the=0Aalternator while the starter is cr= anking.=C2=A0 For a 60A alternator this is=0Aabout 720 watts.=C2=A0 Darn ne= ar 1 HP!=C2=A0 In cars, the alternator is=0Aautomatically put to sleep duri= ng starting by the ignition switch.=C2=A0 In=0Aplanes, it is up to us.

=0A=0A

=C2=A0

=0A= =0A

Bill B

=0A=0A

=C2=A0

=0A=0A
=0A=0A

= =C2=A0=C2=A0


The field is either on or off.=C2=A0

The regulato= r would create too much heat with a linear function, so solution is just a = 'switch' function in the regulator IC.

Battery does the trick in smo= othing the voltage.

George -- simple test is with the engine idling,= kick on the lights/fan... note the rpm drop.
That is the load of the al= ternator turning on. Newer vehicles will have additional inputs to the alte= rnator so it knows when the AC is on, or when you kick WOT (wide open throt= tle) as it will disconnect the alternator and A/C off for a brief amount of= time.=C2=A0=C2=A0=C2=A0 Also a simple battery test is to (in the car) kick= on all loads at idle.... if the engine dies, battery reserve isn't there a= nd time to replace 'em.=C2=A0=C2=A0

Tom

=C2=A0
However, by switching the field on and off at a=C2=A0fairly fast rate an= d varying the pulse
width duration of the field current, a linear= approximation can be achieved with a constant voltage as the result, withi= n the limits of the system of course.
That is in essence how the = voltage regulator achieves its function.
=C2=A0
Jim

Slightly off t= opic, but does anyone have a =0Asuggestion for an off the shelf=C2=A0filter= to kill/reduce alternator electrical =0Anoise? I have an alternator off of= a Geo Metro/Chevy Sprint with internal =0Aregulator. I have a switch on th= e panel to energize the field. After the engine =0Ais running and I switch = on the alternator I get a noticeable hum in the =0Aintercom. This is one of= those nagging little issues I havent gotten around to =0Afixing yet since = first flight.
=0A=0A =0A= =0A=0A=0A=0A=0A
=C2=A0
=0A=
=C2=A0Also in a previous thread someon= e (maybe Al =0AG.?) mentioned an over-voltage protection device for the alt= ernator output that =0Awould be compatible with the internally regulated al= ternator.=C2=A0I'd like to =0Aadd something like that as well - suggested s= ources?
=0A
=C2=A0=0A
Thanks,
=0A
=C2=A0
=0A
Mike Wills
=0A
RV-4 N144MW
=0A
= =0A
----- Original Message -----
=0A=
From: =0A James Maher = =0A
=0A =0A
<= b>Sent: Sunday, March 22, 2009 7:45 =0AAM
=0A
Subject: [FlyRotary] Re: Alternator (Off =0A topic)=0A

=0A =0A =0A =0A =0A
=0A Tom,=0A
You are right, of coarse,=C2=A0about the alter= nator field being =0A either on or off.
=0A
I may h= ave implied that the field current was a linear function but =0A I w= as only=C2=A0trying to
=0A
simplify the explanation.
= =0A
=C2=A0
=0A
However, by switching the field= on and off at a=C2=A0fairly fast =0A rate and varying the pulse=0A
width duration of the field current, a linear approximati= on can be =0A achieved with a constant voltage as the result, within= the limits of the =0A system of course.
=0A
That i= s in essence how the voltage regulator achieves its =0A function.=0A
=C2=A0
=0A
As for your "simple test" it= may not give the expected results, as =0A most modern car engines, = those that are controlled by computers, will =0A have the idle speed= determined by the computer as well.
=0A
So increasing the= load at idle, either mechanical or electrical, =0A will cause the=0A
computer to sense a decrease in RPM and if it goes belo= w a =0A predetermined value the computer will open the throttle (or = idle speed =0A valve) to increase the RPM to the correct idle speed.=
=0A
=C2=A0
=0A
Jim
--- On Sun, 3/2= 2/09, thomas walter =0A <roundrocktom@yahoo.com><= /i> wrote:
=0A
From: =0A tho= mas walter <roundrocktom@yahoo.com>
Subject: [FlyRotary] =0A = Re: Alternator (Off topic)
To: "Rotary motors in aircraft" =0A = <flyrotary@lancaironline.net>
Date: Sunday, March 22, 2009, =0A = 10:03 AM

=0A
=0A =0A =0A
Jim,

The fie= ld is either on or off.=C2=A0 =0A

The regulator woul= d create too much heat with a linear =0A function, so soluti= on is just a 'switch' function in the =0A regulator IC.
<= br>Battery does the trick in smoothing the =0A voltage.
<= br>George -- simple test is with the engine idling, =0A kick= on the lights/fan... note the rpm drop.
That is the load =0A = of the alternator turning on. Newer vehicles will have =0A = additional inputs to the alternator so it knows when the AC is =0A = on, or when you kick WOT (wide open throttle) as it will =0A = disconnect the alternator and A/C off for a brief amount of =0A= time.=C2=A0=C2=A0=C2=A0 Also a simple battery test is to (i= n the =0A car) kick on all loads at idle.... if the engine d= ies, battery =0A reserve isn't there and time to replace 'em= ..=C2=A0=C2=A0 =0A

Tom




=0A =
=0A

1) Re: Alternator (Off =0A topic)
=C2=A0 =C2=A0 by= James Maher <delta11xd@att.net>

=0A =
George,
=0A
I'm sorry to disag= ree with you but you are quite mistaken =0A in your belief= about the
=0A
alternator function.
=0A =
The alternator output is mostly a function of load =0A = because of the voltage regulator,
=0A =
whose function is to keep the voltage constant with =0A = changes in load and RPM.
=0A
It performs thi= s function by varying the field current in =0A the alterna= tor.
=0A
If fact this is one of the many advanta= ges of the =0A alternator over a generator.
=0A =
The alternator's voltage output is also more or less =0A = constant regardless of engine RPM, also due to the regulato= r's =0A function.
=0A
You said = "The alternator charges the battery - which in =0A turn ru= ns the accessories".
=0A
This is not exactly tru= e. If the battery voltage is below =0A that of the alterna= tor output
=0A
then yes the alternator will func= tion to charge the =0A battery, however if the battery is = fully charged then the =0A alternator will not be charging= the battery but will provide =0A the necessary power to d= rive any other loads connected to the =0A system.
=0A=
So reducing the electrical load on the system will i= ndeed =0A reduce the mechanical load on
=0A =
the engine thereby using less overall energy.
=0A =
Hope this clarifies your misconception.
=0A =
Don't feel bad, many people do not fully understand even =0A = the most simple of electrical devices and the =0A = alternator/regulator charging system is fairly =0A c= omplex.
Jim


=0A

-----Inl= ine Message Follows-----

=0A=0A=0A =0A =0A=0A=0AWith the fuel inje= cted rotaries we are dependent on a good source of=0Apower to run the compu= ter and fuel pumps.=C2=A0 I used the information on=0Athe AeroElectric list= to design my wiring.=C2=A0=C2=A0=0Ahttp://www.matronics.com/Navigator?AeroElectric-List= =C2=A0=C2=A0=C2=A0 They have=0Ainformation on what and where to get over-vo= ltage controllers.=C2=A0 Whey=0Aalso have several wiring diagrams for "all = electric" aircraft.=C2=A0 These=0Ainclude ways to feed the Critical B= uss through several=0Adifferent independent paths so one failure do= es not turn you into a=0Aglider.
=0A
=0ADennis Haverlah
=0A
=0A=
=0AMike Wills wrote:=0A
=0A =0A =0A =0A Slightly off topic, but does anyone=0Aha= ve a suggestion for an off the shelf=C2=A0filter to kill/reduce alternator= =0Aelectrical noise? I have an alternator off of a Geo Metro/Chevy Sprint= =0Awith internal regulator. I have a switch on the panel to energize the=0A= field. After the engine is running and I switch on the alternator I get=0Aa= noticeable hum in the intercom. This is one of those nagging little=0Aissu= es I havent gotten around to fixing yet since first flight.
=0A=
=C2=A0
=0A
=C2=A0Also in = a previous thread someone=0A(maybe Al G.?) mentioned an over-voltage protec= tion device for the=0Aalternator output that would be compatible with the i= nternally=0Aregulated alternator.=C2=A0I'd like to add something like that = as well -=0Asuggested sources?
=0A
=C2=A0
=0A
= Thanks,
=0A
=C2=A0
= =0A
Mike Wills
=0A
= RV-4 N144MW
=0A
=0A
-----=0AOrigin= al Message -----
=0A
From:=0A James=0AMaher
=0A
To:=0A Rotary motors in aircraft=0A =0A
Sent:=0ASunday, March 22, 2009 7:45 AM=0A
Subject:=0A[FlyRotary] Re: Alternator (O= ff topic)
=0A

=0A
=0A =0A =0A =0A = =0A =0A =0A
=0A
Tom,
=0A
You are r= ight, of coarse,=C2=A0about the alternator field=0Abeing either on or off.<= /div>=0A
I may have implied that the field current was a line= ar=0Afunction but I was only=C2=A0trying to
=0A
simplify= the explanation.
=0A
=C2=A0
=0A
Howe= ver, by switching the field on and off at a=C2=A0fairly=0Afast rate and var= ying the pulse
=0A
width duration of the field current, = a linear=0Aapproximation can be achieved with a constant voltage as the res= ult,=0Awithin the limits of the system of course.
=0A
Th= at is in essence how the voltage regulator achieves=0Aits function.
= =0A
=C2=A0
=0A
As for your "simple test" i= t may not give the expected=0Aresults, as most modern car engines, those th= at are controlled by=0Acomputers, will have the idle speed determined by th= e computer as well.
=0A
So increasing the load at idle, = either mechanical or=0Aelectrical, will cause the
=0A
co= mputer to sense a decrease in RPM and if it goes below=0Aa predetermined va= lue the computer will open the throttle (or idle=0Aspeed valve) to increase= the RPM to the correct idle speed.
=0A
=C2=A0
=0A =
Jim
=0A--- On Sun, 3/22/09, thomas walter = <roundrocktom@yahoo.com>=0Awrote:
=0A
= =0A
From:=0Athomas walter <roundrocktom@ya= hoo.com>
=0ASubject: [FlyRotary] Re: Alternator (Off topic)
=0ATo= : "Rotary motors in aircraft" <flyrotary@lancaironline.net>
=0ADate: Sunday, March 22, 2009, 10:03 AM
=0A
=0A =
=0A =0A =0A = =0A = =0A =0A =0A
Jim,
=0A =0AThe field is either on or off.=C2=A0
=0A
=0AT= he regulator would create too much heat with a linear function, so=0Asoluti= on is just a 'switch' function in the regulator IC.
=0A =
=0ABattery does the trick in smoothing the voltage.
=0A =
=0AGeorge -- simple test is with the engine idling, kick on the= =0Alights/fan... note the rpm drop.
=0AThat is the load of the alternato= r turning on. Newer vehicles will have=0Aadditional inputs to the alternato= r so it knows when the AC is on, or=0Awhen you kick WOT (wide open throttle= ) as it will disconnect the=0Aalternator and A/C off for a brief amount of = time.=C2=A0=C2=A0=C2=A0 Also a simple=0Abattery test is to (in the car) kic= k on all loads at idle.... if the=0Aengine dies, battery reserve isn't ther= e and time to replace 'em.=C2=A0=C2=A0
=0A
=0ATom<= br>=0A
=0A
=0A <= br>=0A
=0A
=0A =

=0A
= =0A1) Re: Alternator (Off topic)
=0A=C2=A0 =C2=A0 by James Maher <delta11xd@att.net>
=0A
=0A =
George,
=0A
I'm sorry t= o disagree with you but you are=0Aquite mistaken in your belief about the=0A
alternator function.
=0A =
The alternator output is mostly a function of=0Aload because of = the voltage regulator,
=0A
whose function is t= o keep the voltage constant=0Awith changes in load and RPM.
=0A =
It performs this function by varying the field=0Acurrent = in the alternator.
=0A
If fact this is one of = the many advantages of=0Athe alternator over a generator.
=0A =
The alternator's voltage output is also more=0Aor less cons= tant regardless of engine RPM, also due to the regulator's=0Afunction.=0A
You said "The alternator charges the battery -= =0Awhich in turn runs the accessories".
=0A
Th= is is not exactly true. If the battery=0Avoltage is below that of the alter= nator output
=0A
then yes the alternator will = function to=0Acharge the battery, however if the battery is fully charged t= hen the=0Aalternator will not be charging the battery but will provide the= =0Anecessary power to drive any other loads connected to the system.
= =0A
So reducing the electrical load on the system= =0Awill indeed reduce the mechanical load on
=0A the engine thereby using less overall energy.
=0A =
Hope this clarifies your misconception.
=0A =
Don't feel bad, many people do not fully=0Aunderstand even the most si= mple of electrical devices and the=0Aalternator/regulator charging system i= s fairly complex.
=0AJim
=0A
=0A =
=0A
=0A
=0A=
=0A
=0A
=0A =
=0A
=0A= =0A=0A=0A

-----Inline Message Follows-----

=0A= =0A=0A=0A =0A=0A=0A =0A=0A=0A=0A=0A=0A=0A=0A
=0A=0A<= p class=3D"MsoNormal">Mike;

=0A=0A

=C2=A0

=0A=0A

The first thing to try is a large=0Acapacitor a= t the alternator between the B terminal (output) and grnd (the case).=0ATry= about 10,000 microFarad in an electrolytic type. Be aware of polarity to= =0Aconnect it right.

=0A=0A

=C2=A0

=0A=0A

The over-voltage (cro= wbar circuit) that=0AI have I got from Aeroelectric Connection.=C2=A0 I don= =E2=80=99t think he sells=0Astuff directly anymore but maybe you can get it= from B&C.=C2=A0 Connects=0Aacross the field supply circuit breaker, an= d fails to short above something=0Alike 17-18 volts (IIRC) =E2=80=93 trippi= ng the breaker.

=0A=0A

=C2=A0

=0A=0A

Don=E2=80=99t know about y= ours; but normally=0Aautomotive alternators with internal regulators feed t= he current to the field=0Ainternally directly from the regulator.=C2=A0 The= small excitation current=0Arequired to get things started comes through th= e =E2=80=98idiot=E2=80=99 light circuit=0A(one of the terminals on the alt)= .. =C2=A0Over-voltage protection on that=0Acircuit won=E2=80=99t do anything= ..=C2=A0 On my Mitsubishi alternator, I took it=0Aapart and undid the intern= al connection. =C2=A0I learned about this from an=0Aarticle in Contact! yea= rs ago (Issue 46, Sept 1998). Maybe you can find a=0Acircuit diagram for yo= ur alternator; or maybe it is made by Mitsubishi or Nippondenso,=0Aboth of = which are covered in the article. =C2=A0I can provide a copy if that=0Ahelp= s.

=0A=0A

=C2=A0

=0A=0A

Best,

=0A=0A

=C2=A0

=0A=0A

Al

=0A=0A

=C2=A0

=0A=0A

=C2=A0

=0A=0A

-----Original Mess= age-----
=0AFrom: Rotary= motors in aircraft=0A[mailto:flyrotary@lancaironline.net] On=0ABehalf Of Mike Wills
=0ASent: Sunda= y, March=0A 22, 2009 7:37= AM
=0ATo:= Rotary motors in aircraft
=0ASubject: [FlyRotary] Re:=0AAlternator (Off topic)

=0A=0A

=C2=A0

=0A=0A
=0A=0A

Slightly off topic, but does anyone=0Ahave a suggestion f= or an off the shelf=C2=A0filter to kill/reduce alternator=0Aelectrical nois= e? I have an alternator off of a Geo Metro/Chevy Sprint with=0Ainternal reg= ulator. I have a switch on the panel to energize the field. After=0Athe eng= ine is running and I switch on the alternator I get a noticeable hum in=0At= he intercom. This is one of those nagging little issues I havent gotten aro= und=0Ato fixing yet since first flight.

=0A=0A
=0A=0A=
=0A=0A

=C2=A0

=0A=0A
=0A=0A
=0A=0A

=C2=A0Also in a previous thread=0Asomeone (maybe = Al G.?) mentioned an over-voltage protection device for the=0Aalternator ou= tput that would be compatible with the internally regulated=0Aalternator.= =C2=A0I'd like to add something like that as well - suggested=0Asources?

=0A=0A
=0A=0A
=0A=0A

=C2=A0

=0A=0A
=0A=0A
=0A= =0A

Thanks,

=0A=0A
=0A=0A
=0A=0A

=C2=A0

=0A=0A
=0A=0A
=0A=0A

Mike Wills<= /font>

=0A=0A
=0A=0A
=0A=0A

RV-4 N144MW

=0A=0A
=0A=0A=0A=0A
=0A=0A

----- Original Message -----

=0A=0A
=0A= =0A
=0A=0A

From: James = Maher

=0A=0A
=0A=0A
=0A=0A

To: Rotary=0Amotors in aircraft <= /font>

=0A=0A
=0A=0A
=0A=0A

Sent: Sunday,=0AMarch 22, 2009 7:45 AM

=0A=0A
=0A=0A
= =0A=0A

Subject: [FlyRotary]=0ARe: Alternator= (Off topic)

=0A=0A
=0A=0A
=0A=0A

=C2=A0

=0A=0A
=0A= =0A=0A <= tr>=0A =0A =0A
=0A
=0A=

Tom,

=0A
=0A
=0A <= p class=3D"MsoNormal">You are right, of coarse,=C2=A0about the alternator= =0A field being either on or off.

=0A
=0A
= =0A

I may have implied that the field current was = a=0A linear function but I was only=C2=A0trying to

=0A <= /div>=0A
=0A

simplify the explanation.

=0A
=0A
=0A

=C2=A0=

=0A
=0A
=0A

However, by sw= itching the field on and off at=0A a=C2=A0fairly fast rate and varying the= pulse

=0A
=0A
=0A

w= idth duration of the field current, a linear=0A approximation can be achie= ved with a constant voltage as the result, within=0A the limits of the sys= tem of course.

=0A
=0A
=0A

That is in essence how the voltage regulator=0A achieves its functi= on.

=0A
=0A
=0A

=C2= =A0

=0A
=0A
=0A

As f= or your "simple test" it may not give=0A the expected results, as most mod= ern car engines, those that are controlled=0A by computers, will have the = idle speed determined by the computer as well.

=0A
= =0A
=0A

So increasing the load at idle, eith= er mechanical or=0A electrical, will cause the

=0A =0A
=0A

computer to sense a decrease in RPM= and if it goes=0A below a predetermined value the computer will open the = throttle (or idle=0A speed valve) to increase the RPM to the correct idle = speed.

=0A
=0A
=0A

= =C2=A0

=0A
=0A
=0A

J= im
=0A --- On Sun, 3/22/09, thomas= walter <roundrocktom@yahoo.com>=0A wrote:

=0A
=0A =0A

From: thomas walter=0A &l= t;roundrocktom@yahoo.com>
=0A Subject: [FlyRotary] Re: Alternator (Off = topic)
=0A To: "Rotary motors in aircraft" <flyrotary@lancaironline.= net>
=0A Date: Sunday, March 22, 2009, 10:03 AM

=0A <= div id=3D"yiv1127170858">=0A =0A =0A =0A =0A
=0A

Jim,
=0A
=0A The field is either o= n or off.=C2=A0
=0A
=0A The regulator would create too much h= eat with a linear function, so=0A solution is just a 'switch' function i= n the regulator IC.
=0A
=0A Battery does the trick in smoothin= g the voltage.
=0A
=0A George -- simple test is with the engin= e idling, kick on the lights/fan...=0A note the rpm drop.
=0A That= is the load of the alternator turning on. Newer vehicles will have=0A a= dditional inputs to the alternator so it knows when the AC is on, or when= =0A you kick WOT (wide open throttle) as it will disconnect the alternat= or and=0A A/C off for a brief amount of time.=C2=A0=C2=A0=C2=A0 Also a s= imple battery=0A test is to (in the car) kick on all loads at idle.... i= f the engine dies,=0A battery reserve isn't there and time to replace 'e= m.=C2=A0=C2=A0
=0A
=0A Tom
=0A
=0A
=0A =0A

=0A
=0A


=0A
=0A 1) Re: Alternator (Off to= pic)
=0A =C2=A0 =C2=A0 by James Maher <delta11xd@att.net>

=0A
=0A

George,=0A

=0A
=0A

I'm sorry to disa= gree with you but you are quite=0A mistaken in your belief about the

=0A
=0A
=0A

alter= nator function.

=0A
=0A
=0A

The alternator output is mostly a function of load=0A be= cause of the voltage regulator,

=0A
=0A
= =0A

whose function is to keep the voltage consta= nt=0A with changes in load and RPM.

=0A
=0A =
=0A

It performs this function by varying t= he field=0A current in the alternator.

=0A
=0A=
=0A

If fact this is one of the many adv= antages of the=0A alternator over a generator.

=0A <= /div>=0A
=0A

The alternator's voltage ou= tput is also more or=0A less constant regardless of engine RPM, also due= to the regulator's=0A function.

=0A
=0A =0A

= You said "The alternator charges the batt= ery=0A - which in turn runs the accessories".

=0A =0A
=0A

This is not exactly true. If= the battery voltage=0A is below that of the alternator output

=0A
=0A
=0A

then yes = the alternator will function to charge=0A the battery, however if the ba= ttery is fully charged then the alternator=0A will not be charging the b= attery but will provide the necessary power to=0A drive any other loads = connected to the system.

=0A
=0A
=0A <= p class=3D"MsoNormal">So reducing the electrical load on the system will= =0A indeed reduce the mechanical load on

=0A
= =0A
=0A

the engine thereby using less ov= erall energy.

=0A
=0A
=0A

Hope this clarifies your misconception.

=0A =
=0A
=0A

Don't feel bad, many peop= le do not fully=0A understand even the most simple of electrical devices= and the=0A alternator/regulator charging system is fairly complex.

=0A
=0A

Jim<= /p>=0A

=0A

=C2=A0

=0A =
=0A

=0A=
=0A =0A
=0A=0A

=C2=A0

=0A= =0A=0A=0A
=0A=0A=0A=0A=0A

-----Inline Message Foll= ows-----


= =0A=0A --0-795322055-1237812258=:26683--