Step 10: Aerodynamics and Modification

Aerodynamics are important to a car. It's hard to make a car better aerodynamically - but it's very easy to make it worse.

*Blocking your grille has proven to be effective - just remember that your radiator (and grille opening) were designed for the worst case cooling scenario. So monitor your engine temps and adjust your grille opening accordingly.
  • Fold your mirrors. If you can, fold your rear view mirrors in. Just be sure to stay in compliance with local laws.
  • Belly Pan - A significant amount of resistance comes from the open areas under your car. Covering them with corroplast or some other material can reduce your drag coefficient (Cd)
  • Wheel skirts - covering your wheel wells to keep your cars body one contiguous object can help
  • Air Dam - see image, if you car doesn't have one already, this can help
  • Always Drive with your windows up

The best thing you can do to help your aero resistance is to slow down. Resistance goes up with the cube of your velocity (holding everything else equal).
yes, is effective in save money in gas, but it doesn't if you have to buy new brakes. is going to be more expensive the brakes than a few ml. of fuel.
Don't brake during pulse and glide ;) This is a well documented driving technique.
i'm saying that because in downhill the engine make a little inertial brake, and if you turn off the engine, that inertial brake won't work and you have to apply more brakes. in flat surface will work good ;)
It is quite possible to inertial brake with the engine off if you have a manual transmission ;)<br> <br> Then again - on hills, I'd rather use my brake than use my engine as a brake. Brakes even have the name :) Needlessly having pistons slide in the head to slow down your car - it's much cheaper to replace brakes than rebuild an engine ;)
<p>it doesn't really cause any wear on the engine to engine brake (the braking/energy losses is done through the compression of air in the cylinder, not the friction of the cylinders), plus modern engines cut fuel over a certian RPM while engine braking. so if you're going down a steep hill and you find you're having to use your brakes, just put it in gear and don't touch any of your pedels. Once it levels off you can go back into neutral.</p>
I don't agree with the alternator feature. the alternator loads the battery, and doesn't need more power to drive all the electric features, the battery does the job as well. Yes, the faster the alternator goes, the more power generate, and goes to the battery.
<p>It depends on the amperage of the alternator. Not the voltage or how fully charged a battery is. If the electronics are pulling too much amperage then the alternator turns into an electromagnetic brake and starts lugging the engine down.</p><p>My car now has a 70 amp alt. When my bass hits in the subs my headlights dim. My old car had a 120 amp alt (almost double the power output, not voltage) and the headlights never dimmed using the same exact system. </p><p>Its also the reason most cars are switching to LED. FAR less energy draw on the alternator to run them. </p>
Please don't spread rumors for what you don't know! <br> <br>When the car is moving down the road the alternator runs ALL electrics in the car, AND recharges the battery. It ususally only takes a short time to recharge the battery, then that part of the alternators use is done. <br> <br>The batteries sole purpose in life is to start the car. Once started you can remove the battery and car will run just fine and as long as you don't turn it off will run just fine for as long as you want! <br> <br>UNLESS you've added additional electrics to the car, and I mean a lot of additional electric to the car, the alternator can power them just fine, there is no &quot;big&quot; load. <br> <br>All the voltage generated that is not needed by the car/electrics are truned into heat and dissipated into the air. More speed does not mean more voltage generated, thats taken car of by the voltage regulator. The regulator keeps the top voltage output caped at 14.5 approximitely. After a few thousand rpms the output of the alternator does not increase, it stays constant. Same output at 30 as at 80mph. <br> <br>
Generally speaking - the battery is only used while starting. Alternator output will match the load requirement from all electronics from the car. The alternator is<strong> capable </strong>of delivering more power at a higher RPM but will not deliver if the load does not exist.<br> <br> A battery is not an infinite sink of energy storage. You can't add more energy to a &quot;full&quot; battery without damage. Grab an ammeter and measure yourself (I would recommend a clamp on inductive type rather than a shunt ammeter as the current flow during starting will be&nbsp;very&nbsp;high).<br> <br> If you have the&nbsp;opportunity, I highly recommend auditing an introductory course on electrical engineering at a local university. Particularly lessons on Kirchhoff's Circuit Laws (loops and whatnot). I was Mech&nbsp;engineering&nbsp;but really loved the electrical engineering bits :)
that's what i wanted to say, when the battery is full, it have enough power to run any electric device you want, and doesn't mean any fuel consumption, because the alternator is always running. I'm spanish and i don't even know to express myself in some ways, and i'm a automotive technician and we learn Kirchoff's law too. Have to take a look, because i have some aspects that i don't remember, 3 years have been passed since that
You're somewhat familiar, excellente! If we were to represent the vehicle loads (computers, lights, valves, etc.) as one single load for simplicity - we could draw the circuit diagram with three components in parallel. Those components are the alternator, the vehicle loads and the battery.<br> <br> The alternator is source, the battery can be represented as a capacitor as it is near full and the loads can, for simplicity be represented as a resistor (lets not mess with inductance).<br> <br> Before the car is started, the battery is around 12.5V<br> <br> When the vehicle is started, current flows from the battery through the loads and bypasses the current source.<br> <br> Next, the alternator takes over. The&nbsp;voltage&nbsp;off the alternator is higher than the battery (13.8-14.5V or so). Current flows into the load. Because the alternator's voltage is higher than the battery, current can also flow into the battery. As the battery voltage increases (as it will for this chemistry), current slows down until the voltage equalizes and current can not flow. This is why we can represent the battery as a capacitor. When a capacitor is fully charged, it is effectively an open circuit.<br> <br> From this point on, current flows from the alternator to the load and&nbsp;bypasses&nbsp;the battery (as it is &quot;open&quot;).<br> <br> -----<br> Now, an 80amp <strong>rated</strong> alternator does not always put out 80A. If the load only calls for 10A, the alternator only puts out 10A. We can not have this equation out of balance (energy in must equal energy out + entropy losses). Simply, the current that goes in must be consumed. When the car demands more current, the alternator supplies it and in turn the alternator requires more torque from the engine to turn.<br> <br> More torque means more fuel consumption. With an instantaneous fuel gauge, this can easily be seen be comparing idle fuel consumption with little electrical load to fuel consumption with as much load as possible (high beams, defroster, vent fan without a/c, brake lights, hazard lights, power windows in motion, etc.)
The amperes become through the resistance of the material (more loops on the alternator), doesn't mean more torque. The engine has the same torque all the time (crankshaft, camshaft, and so on) are spinning with a minimum torque when it starts, the torque is only needed for the wheels to keep on the ground, excessive torque=wheelspining you don't want an alternator do this.<br><br>http://automecanico.com/auto2002/alter4.jpg<br><br>alternators work like engines, there's minimum friction, only for + and - contacts ( they have to spin to connect the wires obviously)<br><br>NOW, what you want to do, is turn, for example, water pump, fuel pump, the engine fan and so on, running electric, that will be less load on the engine and the alternator is capable enough to run all this elements, is designed for this use, A/C, the stereo, airbag control system, fuel injection... everithing is going with current nowadays and brands desing better alternators to handle up this loads. (Toyota prius, for instance, nuff power to pull out their own motors that are the alternators itselves)
I went driving one day in an older, low powered car. We were towing a caravan, and the car was jjuusstt coping with slight ups and downs. Then, when it got hot (we had started in the cool morning), we turned on the air-con. <br>Yup, aircon does make a difference. Now we could only tow it on the downhill, and acceleration was pitiful.<br><br>The load on the alternator does effect the strain on the engine.<br><br><br>And, if you want to prove it to yourself, grab a cheap DC motor. Spin it, see how easy it turns? Now solder a wire across the two contacts (shorting them). Now it is a lot harder to turn. The wire simulates a huge load, like what radios and air conditioning will place on a cars alternator.
trebuchet03 I'm just getting on the scene here, doing some research. I'm giving a lot of weight to your comments. You seem to know your stuff. It looks like you and another poster were speaking around each other. I think the other poster has it mixed up a bit, in that an alternator and typical electric generator/electric motor work a bit differently. Specifically where &quot;Magnets&quot; are concerned. Please correct me if I'm wrong.<br><br>If I'm correct, as are you, the increased spinning of the alternator will not increase output. It's not the input spinning that's the factor but the load placed on the alternator. The alternator will meet the load without an increase in the input rotation.<br><br>Again, please correct me if I'm wrong. Do know if you'll see this but if you do I'd appreciate your response.
they have some voltage regulators inside that keeps a constant voltage no more than 14v
<p>Nope. This is false. I have an OBD Bluetooth connection to my tablet. This method sucks up fuel like a sponge. A nice slow acceleration is what is best, besides truckers (who have Standard Transmissions) do the same and they're all about conserving fuel. My car is an automatic.</p>
<p>Agreed. I use Torque on my tablet and slow and easy is the best way to accelerate. Ive tested it over and over while watching fuel flow, engine load, time, distance, etc. But us truckers start off slow because we have 13 gears to go through not to mention they weigh 80,000lbs. Plus most new trucks have an auto acceleration on take off. Meaning the engine idles up on its own as you raise the clutch. If you arent fully loaded you dont even have to touch the gas pedal until 3rd gear.</p>
<p>Keep in mind, if you have a torque converter automatic, trying to make the transmission go to lock-up or soft lockup as early as possibly is good for fuel economy. The more a torque converter slips, the more waste heat end ups up in the transmission. Also if you press too much on the gas, the engine computer may have the engine run rich, as in lower than 14.7:1 air to fuel ratio.<br><br>A scan gauge or torque smart phone app thing can help with this</p>
<p>In traffic (city driving) keep a large distance to the vehicle in front of you to reduce the probability of having to break. This is also safer, as you have more time to react.</p><p>On the highway, I would suspect tailgating increases fuel economy because it decreases drag. You have to watch in front of the vehicle(s) you are tailgating and anticipate obstacles that will cause the driver(s) in front to break.</p>
<p>To avoid stopping at a red light, try to arrive there just after it turns green again; if there is traffic stopped at the light, arrive just after it is leaving. This usually means breaking lightly, rather than coasting, as soon as the turns red. If you coast you might arrive too early and have to stop. But do not break too hard. Start breaking lightly and increase your breaking, always keeping your speed strictly above the speed required to coast to the light. Knowing the optimum speed comes with experience.</p>
It takes a lot of power to get up to 40 MPH, even going from 30, this glide on/off idea is not only dangerous, but cannot stand to be truly effective, you're using a lot of an engines power to make it back to 40 MPH, this may be different for electric/hybrid cars running on the electric motors, which in turn use deceleration and braking to generate more power but on a traditional gas powered car this would not be a productive enough maneuver to outweigh the danger you present to other motorists by the constant accelerating/decelerating.
<strong>...but cannot stand to be truly effective...</strong><br/><br/>The pulse and glide method has been empirically tested by many people. Remember, while linear energy (momentum) is conserved - power is not. This is where the pulse and glide method shines. As for danger, possibly. I find myself much more alert and in every defensive driving course I have taken - evasive action is done by braking and steering.... Not gas and steer ;) Also take into consideration that you should be giving yourself plenty of space to begin with ;)<br/><br/><a rel="nofollow" href="http://www.metrompg.com/posts/pulse-and-glide.htm">Here's Just one, well written example</a><br/>
I still find it questionable, but this isn't a forum for discussion, thank you for the link, thats all I'll say on the subject.
<em>I still find it questionable,</em><br/><br/>That exactly the attitude I want from people :) And I mean that with no sarcasm whatsoever :D Go out and test for yourself, see what data you end up with :D There are some better explanations out there which I can dig up if you'd like - but all I ask is that you keep an open mind :)<br/><br/>But, as a quite example from my numbers.... I might pulse for 7 seconds while getting 20 or so mpg -- and then I'll glide for at least double that getting ~180-200 mpg (that's engine on, clutch off). If I were cruising for that same 21 second period, I might be getting 31. That's not enough information to put everything together (I'll have to go out to my car and grab my notebook for that), but perhaps that glide number brings it into the realm of feasibility for you ;)<br/>
The correct answer is that for most vehicles pulse and glide results in worse fuel economy. It only helps with specific vehicles, most of which are hybrids.<br><br>The problem is the method was suggested as if it applies to any vehicle (by omission of vehicle parameters necessary to benefit from it) when for &quot;most&quot; people it is worse because most people don't own applicable vehicles.
I must have forgotten my 2003 5.4L V8 F150 was a hybrid... I can get about 25 mpg on the highway, quite an improvement.
Correction: air resistance/drag goes up as the velocity squared, not cubed.
No real pay off here. My old 87 Oldsmobile cutlass achieved 21-23mpg highway with a carbed 5.0L V8. This is one of the most non-aerodynamic cars ever made, but! A new V8 dodge charger only gets 17-18mpg. Something most likely a lot more "aerodynamic" than an old square 4000 pound muscle car, but yet it achieves even less fuel mileage. One the of the most aerodynamic cars, the smooth looking mid-late 90's camaros only achieved 24-28mpg. Aerodynamics has very little to do with MPG unless one is planning on driving 200 MPH. Sorry to be a negative Nancy, but it's true.
Aerodynamics don't matter until 200mph!? Try riding your bike behind a semi and then against the open air.<br />
LMAO but true. that's why bike racers on Tour de France wear those helmets and not a block shaped one
Once 4000 pounds of car is no longer accelerating (say you've stopped at your cruising speed of 70mph), it takes no additional force to move the mass of your car EXCEPT that of resistance forces coming from: 1) Rolling Resistance 2) Aero Resistance Ride a bike on a windy day and tell me that aerodynamics doesn't matter. You're comparing different cars, with different power trains and making a link to aerodynamics. That is what's known as a fallacy ;)
Not true again. an 87 olds cutlass vin 9, and some vin y's used the 4 speed overdrive 200-4R. Every single GM car has used the 200-4R and 700-R4(a less efficient but tougher trans.) since the late 80's up until the early 2000's The 4L60 and 80's are nothing more than an electronically controlled 700-R4. As for the engines, not much has changed, still 5.0L, 5.7L 90deg roller V-8. The fuel, electronics and induction has changed over the years, but still the same. Simply look at the EPA rated MPG figures for each. There is no major change, or difference. On some models there has been a change for the worse. As with the 4.6L ford. The fuel economy has dropped since going from the 5.0L going to the "modular" 4.6L. No real positive change. hope that makes some sense for you.
So you're saying your 87 cutlass has the same shape as a charger and camero and the same exact power train (mind you, electronics is an integral part) - and then go on to say the changes that have been made (and some not so good). Honestly, I don't care about what changes have been made over the years - if they are not identical, you're practicing bad science. Again, when you want to make a link to aerodynamics - control everything, except aerodynamics. Here's a perfect example - the TV show myth busters did a bit on Tailgate up versus down. They took two identical vehicles (brand new, same mileage), then had one tailgate up, and one down with rules fro driving technique. Same power train, a best effort to control driving technique, two different aerodynamic configurations and a full tank of gas. 800 or so miles later, the truck with it's tailgate down ran out of gas - the other truck ran out of gas around 40 or so miles later. Later, it was empirically tested with a fuel consumption meter -- again, tailgate down consumed more fuel.
&nbsp;OMG, if aerodynamics didn't make a difference then why is there such a term?
True, if you look at any race vehicle you will see any or all of the following: 1) a spoiler, this is a airfoil that uses the wind to keep contact to the road, why because the natural aerodynamics of a car suck and that mostly is from air going under the car which leads to the next item. 2) a splitter, this is a curved gap filling board of sorts, this is used to get the vehicle as close to the ground and diminish the gap, or reduce drag and improve aerodynamics. So anyone that says aerodynamics is fake or doesn't work..... well haha go on paying for gas as we pass you at the gas station..... haha
So, basically you're saying that if electronic engine control really makes milage better, or at least wasn't just an unnecessary complication, then a more aerodynamic car should not have lower rated milage, am I reading you right? Two things have changed: engine control and car shape. So assuming that the new engine control is better, it must be the car shape causing the lower milage. But since we know from experience that wind resistance does actually matter, we may have just proved that most electronic engine management is all smoke and mirrors. Another possibility is that you're quoting sports cars, which are generally tuned for downforce. Of course, downforce gives you more grip, but robs your straightaway speeds and fuel economy, which is especially obvious in stock car racing. I do know, though, that my dad's '93 Olds Cutlass gets embarrassingly close to a brand-new Milan's milage, with more than 120,000 hard miles on it's clock. There's something amiss there from a technology standpoint.
that's what i'm talking about, playing with throttle and RPM. Low rpm = low fuel --&gt; FALSE Low rpm make the time lapse between injections increase, so we get less fuel in a second, that's true, but, if we have to step more the throttle to get the same rpm, the volume of fuel increase, and the car needs energy to move and spend more fuel. you have to play with what your engine needs and, at the same time, manage the efficiency of the fuel you send to the engine
best rpm shiftings on petrol: 2000 to 2500 RPM<br>best rpm shiftings on diesel: 1500 to 2000 RPM (lower rpm torque point)
To your earlier comment - this is why instantaneous fuel economy data is important ;)<br> <br> Yes, we care about long term average consumption - but you won't get good long term averages if you can't keep your instant consumption low (as you accurately said: &quot;play with what your engine needs&quot;).
yes, i've just realize about that ;)
There are so many things wrong with this instructable I don't know where to start.<br><br>Do not over inflate tires. It is dangerous, should be illegal and might be, will wear them irregularly in the middle regardless of being radial belted. The proper inflation level depends on the vehicle weight and is usually stamped on the the vehicle door sticker or elsewhere.<br><br>Seats don't usually weigh 100+ lbs each, even if they are motorized, not even a full bench rear seat.<br><br>There is nothing to &quot;tune&quot; on a modern fuel injected, computer controlled engine. It's sort of a myth perpetrated by youngsters repeating what old timers said back when engines could be tuned manually without reprogramming a memory chip.<br><br>It is very ill advised and dangerous to suggest not using air conditioning (heat delirium while driving causes accidents), or defrosters (which you'd only use to get rid of frost, it's illegal to not keep visibility by choosing not to use a defroster when needed). Further, if you can't see traffic or traffic control lights, signs, etc, due to frost or fog you can't plan your acceleration and deceleration as well.<br><br>One thing not mentioned was that on some vehicles you can change the vacuum tube configuration to make the AC system blower blow out the defroster ducts without it in defrost mode so you can clear windshields without running the AC compressor and incurring the additional engine drag, but be sure to keep the vac system a sealed system as an open (leak) will cause CEL to come on and you'd be in the inefficient computer open loop mode in many cases.<br><br>Pulse and Glide driving is not proven to increase mileage in general, only with hybrids and certain ICE vehicles. With most (other) vehicles the more effective driving is to accelerate at the engine's peak efficiency RPM then maintain approx 40 to 45 MPH, or the speed limit if it is lower than 40 MPH. This in fact _has_ been proven constantly to have better fuel economy. Pulsing up to speed again is &quot;usually&quot; less efficient than maintaining the average speed. Of course certain engine and transmission combinations can change this, but it was suggested as if it's always an improvement to pulse and glide when it isn't.<br><br>Constant throttle up a hill does noting to improve fuel efficiency. Keeping the throttle varied so the engine always stays within its peak efficiency RPM is more fuel efficient.<br><br>Engine off coasting may be illegal, but it can be done safely if the driver is either very strong/small car so steering effort is manageable, or it has electric steering so the battery is enough of a reserve to power it. Brakes are the same thing, there is reserve pressure for one stop or pumping can build it up, but of course either is still less safe.<br><br>The suggestion about 50-75% throttle is only valid for small cars with anemic engines and matching gear ratios/shift points, with no traffic around. Otherwise you could be accelerating too fast, unsafely and putting stress on the vehicle and tires. Often if you accelerate a little slower, you have more time to react to road conditions or vehicles ahead of you. Point is, the exact situation changes which acceleration strategy is most efficient.<br><br>Blocking your grill has not proven to be effective, except on select vehicles! You're making blanket statements that are incorrect a large % of the time. It is not just a matter of reducing drag or cooling system temperature, it is a matter of how the computer changes engine fuel air mix due to the temperature of the engine. Sometimes it helps, other times not. It will have to be tested per each vehicle and also with different driving speeds and ambient temperatures. Also, most cooling systems rely on electric motor(s), it causes more alternator load to block the radiator.<br><br>To summarize, sometimes these strategies help but other times they not only don't help but increase vehicle wear, risk of an accident, road rage from other drivers, and are illegal. It is no more reasonable to break laws to save gas than to break laws because you feel like robbing a bank to buy more gas. Vote to change things, and petition your government representatives for change.
just look at the tyre that's on the picture, is like a ballon, overinflated and blown up
1). Additional electronic devices NO NOT use more horsepower or electricity. The alternator(the device that supplies power while the engine is one) is on all the time, it can not be switched off and it does not require more effort to draw more power. The magnets inside do NOT increase in polarity. I would love to know who made this myth up about elec. devices using more power. They cause more heat build up and if you draw more power than the alternator can supply or over tax it, it will fail in time, BUT IT DOES NOT TAKE MORE HORSEPOWER AND OR FUEL! An A/C system does(when it is on) because it is switchable and not on all the time, but an alternator is on ALL THE TIME, turning on headlights does not take more fuel economy away. 2).Same thing with defroster wires in the rear window, electronic device, no economy loss. Front defrosters(defogers) on some cars turn on the A/C unit and this can consume horsepower to turn the A/C unit, but this is not on all cars, some cars supply heat from the heater core to defrost/defog the front windshield.
<em>The alternator(the device that supplies power while the engine is one) is on all the time, it can not be switched off and it <strong>does not require more effort to draw more power.<em><strong></strong></em></strong></em><br/><br/>On the contrary, the higher the load placed on any generator, the greater torque required to turn it.<br/><br/>The next time you get a chance to - put a load on an alternator that hasn't been installed and then try to spin it... You'll feel a bit of resistance. Then, increase that load - and you'll feel even more resistance. It's not voodoo, it's classical physics (which, in some cases, appears to be voodoo :p). This same experiment can be done on just about any motor ;)<br/><br/>An analogous example would be to say that when you're walking, it doesn't matter how much weight you carry - you're walking anyway and you're not stopping. Anyone that has ever moved house or carried &quot;stuff&quot; can say that walking can be severely restricted when you put a high load on yourself (stuff).<br/>
What would you say the minimum RPM for an alternator test? I have two set aside for the windmill instructable and I have yet to get them a charge. Any advice would be appreciated, Thanks!
if you hook a volt meter up to the alternator then doing something as simple as turning the alternator by hand will give you voltage you wont get any kind of current, but you should at the very least see a few volts to around 14 volts. Most modern day alternators need to have at least 12V supplied to them(the alternator shuts off at below 12V to prevent damage to the electrical system of a car) in order for them to be energized and the ignition terminal on, or shorted for it to even start supplying it's own current, without it the alternator just sits there.<br/><br/>You probably want to find an old generator/alternator, the kind without a built in regulator and only has 1 wire, like on older 1960's chevy's and ford's, that way there is no sensing wire or regulator and it should always be supplying power. Here's a good article for you to read as I'm probably a bit rusty on the subject. <a rel="nofollow" href="http://www.autoshop101.com/trainmodules/alternator/alt101.html">http://www.autoshop101.com/trainmodules/alternator/alt101.html</a><br/><br/>As far as a minimum RPM, there really is none, the faster you turn it, the more power you get, to a point that is.<br/>
<em>Here's a good article for you to read as I'm probably a bit rusty on the subject. <a rel="nofollow" href="http://www.autoshop101.com/trainmodules/alternator/alt101.html&apos;&apos;">http://www.autoshop101.com/trainmodules/alternator/alt101.html''</a></em><br/><br/>Interesting link in that it states this...<br/><em>When charging system voltage falls below this point, the regulator will increase the field current, thus strengthening the magnetic field, which results in an <strong>increase of alternator output.<em><strong></strong></em></strong></em><br/><br/>Since voltage is directly and proportionally related to current via ohm's law (V=IR) AND voltage is nominally constant (as a result of stator regulation) - the above is very accurate. Alternator output is generally measured in watts (suitable since a watt is a unit of power) - and to find watts, multiply current by voltage. Voltage, again, is nominally constant. Current must increase in order to increase the aforementioned output. At least, this is a top down (backwards) explanation (trying to attempt an explanation from another angle). &lt;-- as a side note, this is the reason why you can diagnose some alternator issues with a voltmeter and a static/dynamic load. It's also the same reason why batteries shouldn't be tested without a load (it just doesn't tell you much other than it's ability to hold a surface charge).<br/><br/>This can be observed with an ammeter (not a voltmeter) - I highly recommend you give this a shot - just make sure you have an ammeter with a high enough current rating (most cheapo one's have a 10A fuse).<br/><br/>Alternatively, you can look at someone else's measurements (but I still recommend you do the same test to see for yourself). <a rel="nofollow" href="http://www.metrompg.com/posts/alternator-optional.htm">See Here</a> specifically, this chart...<br/>Item...................@ 14.4v<br/><br/>Idling ............... 128w<br/>Rev up to 3500 rpm: .. +35w<br/>Heater fan setting 1: . 55w<br/>.. Setting 2: ......... 98w<br/>.. Setting 3: ........ 141w<br/>.. Setting 4: ........ 189w<br/>Marker lights: ........ 95w<br/>Full lights: ......... 240w<br/>A/C (heater fan<br/>subtracted, but<br/>incl. condenser fan):. 163w<br/>Defroster: ........... 104w<br/>Wipers 1: ............. 48w<br/>Wipers 2: ............. 76w<br/>Radiator fan: ........ 144w<br/><br/><em>As far as a minimum RPM, there really is none, the faster you turn it, the more power you get, to a point that is.</em><br/>The diode bridges will have a minimum breakdown voltage that you'll need to overcome before you'll start seeing any output ;) This will vary by design, of course.<br/>
you aren't running all this stuff all the time! If you do, i thing will before burn your electric installation for the amperage of this stuff running lol
But there is a minimum RPM. where the alternator, will start producing the power desired, if I'm allowed to state the obvious. :). For a particular automotive alternator refer to a service manual for a vehicle in which is installed. You should be instructed at what engine speed the charging system tests are to be made with. Armed with that figure, measure pulley sizes to calculate the RPM of the alternator.
<em>guy doesn't seem to understand that once the device is spinning and energized, that is the total amount of resistance, or force you will feel, it will increase as RPM goes up(force required to turn it, hence the parasitic drag), but NOT when an additional load is placed upon it. </em><br/><br/>This is false, please this is fundamental physics - the type that used to be taught in high school. Power generating devices (alternator, generator, etc.) can not put out more current than is being drawn - it needs somewhere to go, this flow is called current - something that is measured with an ammeter, not a volt meter. The torque resistance will be related to the current flowing, not voltage.<br/><br/><em>I didn't get my ASE certs for nothing </em><br/><br/>If we're going to throw around pieces of paper.... I didn't get the degree in engineering for nothing either ;) I'm just glad it was paid on scholarship :D<br/>

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