Why Don’t Electric Cars Have Alternators?
A common question we get about D.I.Y. Electric Car projects is “Why don’t you just add an alternator to charge the car as you drive?”
So, how about it? If fossil-fueled cars have alternators to charge their battery, why don’t electric cars just do the same?
To find the answer, we need to know how an alternator works and where the energy comes from.
ALTERNATORS:
An automotive alternator is a type of generator which creates Alternating Current (AC). A belt from the vehicle’s engine spins a pulley which is connected to the rotor of the alternator. On the shaft are either permanent magnets or copper wire coils with a small DC current flowing through them. The flow of current creates a magnetic field. As the shaft rotates, this magnetic field induces current to flow in a matching stationary set of coils. Because the magnetic fields on the rotor alternate polarity (north/south), the direction of the flow of current induced “flip-flops” many times per second, reversing direction as well. We normally call that “Alternating Current”.
The alternating current is converted to direct current (DC) with diodes, and a voltage control circuit makes sure that the output voltage is appropriate for charging the vehicle’s 12V battery.
ENERGY SOURCE:
Where does the original source of energy for the alternator come from?
Scientists such as Galileo, Newton, and Bernoulli studied the natural world and came to realize that there are certain “rules” that are always followed. This eventually came to be known as the Laws of Thermodynamics.
According to the Law of Conservation of Energy, “Energy can neither be created nor destroyed; rather, it can only be transformed or transferred from one form to another.”
In the case of the alternator, the fossil fueled engine (connected by a belt and pulley) provides MECHANICAL* energy to the alternator which converts that energy to ELECTRICAL energy. The electricity isn’t “created”, it’s just some other form of energy which is converted. That means an equal amount is given up from the engine. The engine has to work harder and burns more fuel to be able to provide this additional energy.
Another important concept to remember is that the mechanical energy of the engine is not PERFECTLY converted to electricity. Some of it is converted to noise, heat, and vibration. Although efficiency is far from 100%, it’s still very useful to convert mechanical energy to electricity to charge the battery and run the electrical systems of a vehicle.
SO, WHY NOT IN AN ELECTRIC CAR?
If an alternator works fine to charge a battery, why don’t we use one in an Electric Car?
The two main reasons are:
1) An E.V. doesn’t have an engine
2) There’s a BETTER device to use than an alternator.
Remember, the ENERGY that powers the alternator is actually the mechanical energy created by the engine through combustion of fossil fuel. An electric car doesn’t have an engine or gas/diesel fuel. Instead, it has an electric motor and rechargeable battery. We COULD use the battery to spin the motor to spin the alternator to generate electricity. BUT at best, we would simply be using electricity to make electricity. Even worse, there are still losses on the way. Conversion losses often show up as heat, but noise and vibration as well. Essentially, using an alternator powered by an electric motor, we could only ever make a smaller amount of electricity than we started with. (If we could create an equal amount or more, we would have a Perpetual Motion Machine.) However, we COULD make a different voltage. An electric car battery pack is typically over 300VDC, whereas we only need a 12V system for headlights, radio, and other accessories.
DC/DC – A Better Way:
If we only want to convert direct current from one voltage to another, there’s a much more simple and effective way to do it. That’s through a device called a DC to DC Converter. This is an electronic device which takes direct current at one voltage and converts it to a different voltage. It’s still not “free energy”. Converting to a higher voltage means also getting a lower current. Getting higher current means also getting lower voltage. Either way, it’s still the same amount of energy, minus losses, which show up as heat. Basic DC/DC converters dissipate the heat through a metal case. Higher power converters have heat-sinks, fans, or even active liquid cooling.
DC/DC Converters have several advantages over alternators. They are compact. They save weight. They are more efficient. There are no moving parts – no belts to replace, no pulleys, no bearings. That also means they are maintenance free.
If you purchase a DC/DC converter for your own DIY Electric Car project, keep in mind the input voltage and the maximum power. You want the input voltage it’s designed for to match the voltage of your battery pack. Many converters allow for a range of input voltage and are listed as so. For example, one might be listed as “48-96V IN / 13.5V OUT”. Power is rated in the maximum number of Watts that can be produced by the converter. In a car, you need enough power for the headlights, radio, and other accessories. This might be as much as several hundred watts. Remember to fuse the output of the DC/DC converter, and use appropriate gauge wiring for the output current. With rare exceptions, a DC/DC converter is always still combined with a 12V battery, just as an alternator is.
Electric Motor AS Generator:
Lastly, the AC motors used in commercially-built electric vehicles make excellent generators. But you still can’t magically create power while driving the car. Remember, we can only CONVERT energy from one form to another. There are still times when this is useful. Converting the KINETIC energy of a car to some other form (electricity to charge a battery, or heat of friction from traditional brake pads) will remove the kinetic energy and thus SLOW DOWN a moving vehicle. This is perfect when you want to slow down anyways! On an EV, we exploit this and call it “Regenerative Braking”. It’s a great way to recapture some of the energy used to originally accelerate the car, and increases the total efficiency of the vehicle.
In another scenario, a vehicle can be coasting down a large hill or mountain. The POTENTIAL energy is converted to KINETIC energy. In a manual transmission fossil fuel vehicle, the driver might downshift and use the compression of the engine to help slow the vehicle. In an electric car, the motor can charge the battery to do the same. It should be noted that the battery needs to be at least partly discharged to have a place for the electricity to go for regenerative braking to work. Better to live at the bottom of a mountain than the top of a mountain, as a fully charged battery won’t be able to accept any more charge through regenerative braking.
Alternators are neat technology, allowing us to convert mechanical energy into electrical energy. Similar technology is used on a large scale to generate electricity at power plants. Alternators work great for fossil-fuel-burning vehicles, but are complicated, inefficient, and high-maintenance compared to DC to DC Converters used on Electric Vehicles.
We hopes this give you a better understanding of alternators and electric vehicles for you to be able to work on your own Electric Vehicle Project.
-Ben Nelson and the 300MPG.org team
*A fossil fuel engine actually takes CHEMICAL energy (in the form of gasoline, diesel fuel, etc.) and ignites it, converting it to THERMAL energy which then moves a piston (LINEAR MECHANICAL ENERGY) which then turns a crankshaft (ROTATIONAL MECHANICAL ENERGY) which only THEN goes to the alternator via a belt. Energy is lost at every step of the conversion process.
Even worse than that, we need to get the fuel for the vehicle to start with. It takes a tremendous amount of energy to search for oil, drill for it, transport it, refine it, ship it to a gas station, and then finally get it in our fuel tank.
When we look at a total “Well-to-Wheels” scenario, a modern passenger car is possibly the most INEFFICIENT machine in human history.
{ 50 comments… read them below or add one }
Why not apply an alternator to the hubs or spindles of the wheels. The motion of the car rolling is your energy being transformed into energy going back into the battery.
Most electric cars have regenerative braking. When slowing down, the motor becomes a generator and recharges the batteries. No alternator needed.
An alternator takes very little energy to spin it. To say that you would be loosing more in the transfer is ridiculous. I have made homemade water wheels that I attached and alternator to and was able to have electricity to run lights. This was simy using tg h ed flow of a small stream. This shows how little energy need to spin the alternator, which on turn produces twice the energy put in. ⁷ My belief is that we could have very efficient electric cars, if and only if the capitalists can figure out a way to profit from it. As long as those in power are making money from a renewable resource, but convincing everyone that its comes from fossils and that there is limited supplies, then we are screwed. Just saying.
An alternator does NOT put out MORE energy than it takes in.
For a water wheel or hydro-generator, the source of the energy is the weight of the falling water. Now imagine that the energy made by the water-wheel generator has to pump the water back uphill to power the generator. That’s exactly what you are trying to do if you want to spin an alternator from an electric motor and then use that electricity to charge the battery to run the motor.
It’s like trying to pick yourself up by grabbing your own belt and lifting.
Spinning an alternator is very different than getting a significant amount of power out of it. The more power you are getting out of it, the more the electro-magnetism resists and the more drag the alternator puts on the engine. An alternator is a lossy way of converting mechanical power to electrical power
Energy needs to come from an external source, like charging a battery from wall power, from the movement of falling water, or filling a fuel tank with gasoline. You can never get more out than what you put in.
https://300mpg.org/projects/electro-metro/perpetual-motion/
I think you are skipping Mark’s point.an alternator/ Dynamo on each hub would have very little rolling resistance and should be able to add to the regen system while driving and not braking.I really cba to do the calculations, but his idea does hold up as a constant top up.
I know EXACTLY how to install an alternator that almost continuously charges the battery. It’s very simple…But I will talk to Mr. Elon Musk only. IF there’s anyone who could get me such a meeting. I would certainly compensate them. #(321)216-7114… Call ANYTIME.
I seen the above response now and your explanation makes sense. The electric motor would still have to produce the power to spin the alternator thus cancelling each other out.
Why not use four wheels as pullies for four individual alternators to charge a complete free set of rechargeble battries, waiting for the cars clever system to select/replace new pack when it’s almost run out with curret pack, and then alternate to use the new batt pact whilst the current one will be charging….Two system to run as one …there will be no conflics and all electric cars can probably work to full potential without having to stop to charge.
Perhaps you should read this article: https://300mpg.org/projects/electro-metro/perpetual-motion/
Permanent magnet alternator, without iron core, less drag. Pancake 2 or 4, gets same job done.
Listen. The electric motor is already having to spin for the car to move. If u add an alternator it will be able to power the alternator no problem. It just needs to be charged manually one time. And if the alternator doesn’t completely charge the battery. It WILL get more range.
Hi Landon,
The electric drive motor in an EV certainly can spin an alternator no problem. The issue is that it will be HARDER to spin because of the resistance from the alternator. (Not just the bearing, the belt, etc. An alternator is HARDER to spin the more current it is producing as the mechanical energy gets converted to magnetism to electricity.)
The alternator is never going to produce more power than it wastes.
The electric drive motor will need to use MORE extra energy to spin than what the alternator can make.
If you COULD get more out than you put in by adding an alternator, why wouldn’t we want to add as many alternators as possible? Maybe add 8 or 10 for even MORE range?
We don’t because it doesn’t work that way.
If you only mean to have the drive motor to spin an alternator to charge a 12V battery – to change some high voltage main battery power to lower voltage accessory battery power, that can work. (You STILL don’t get more power out than you put in!) However, an alternator is inherently lossy, because it’s a mechanical device. A DC/DC converter is a smaller, more efficient, electronic device with no moving parts, which performs the same duty.
With rare exceptions, an EV will have a DC/DC converter to keep the 12V system topped off.
Why can’t you have a small gas engine in an electric car that could trickle charge the batteries?
You CAN have an engine slowly charge an electric car!
But at that point, it’s a plug-in hybrid, not an electric car.
The BMW i3 with Range Extender does exactly that.
At one point, I also played around with my Geo Metro Electric conversion turning it into a hybrid using an LP generator.
All those thinking an EV can recharge its own batteries and not need to charge from external power while its driving using dynamos or alternators attached to the EV Motor or drive shafts or wheels fail to understand how generators work when they are under load. Sure they seem to spin fairly freely when nothing is connected but when you place a load upon them, the loss of electricity to the load puts strain on the electromagnetic field (back EMF) in the generator which thus makes it harder for the generator shaft to rotate at the same speed it was when there was no load placed on it by a charging system. The alternator clamps down with backward mechanical resistance due to the increased loading of having to charge the drive batteries which backfeeds resistance to mechanical rotation on the drive system and thus puts higher demand on the EV motor to push harder to maintain the required speed thus the drive electronics have to pull increased amounts of power from the drive batteries and thus your charging system sees more drain than before the alternator kicked in on the batteries and accordingly now charger has to pull more power from the alternator again to cover the increased rate of battery drain and that puts more mechanical rotation resistance back feeding from the alternator covering the elevated power use to the charger through the drive train to the EV motor which then again needs slightly more energy to maintain the current drive shaft rotational speed (MPH) due to increased exertion needed to overcome additional mechanical resistance backfed to it from the alternator which requires the drive electronics to again up their pull from the drive batteries and the whole thing loops over and over again steadily pulling slightly ever more and more power from the drive system and thus batteries overtime to supply more charge needed by the charging electronics charging those same batteries to compensate self-created rising levels of power drain from the batteries. This trend to lose more and yet more still over time between two interconnected opposed-purpose systems is what is called a negative reinforcement feedback loop. This will run your car down faster because of all the additional losses you wouldn’t have additionally imposed if you hadn’t added the alternator and its associated drain upon the drive system in an attempt to recharge the batteries while those same batteries drive the car because the recharging energy will due to inefficient of conversion and fictional losses always creates a slightly higher demand upon the batteries to cove what it can deliver back to the batteries to recharge them, thus spiraling the battery energy down faster and faster to maintain the same road speed and much more quickly running the batteries down. The attempt to self recharge the batteries in a quest for additional mileage thus actually results in less overall mileage because all the difference between returned energy which is always less due to additional losses to conversion inefficiency and fiction imposed which are significant and unavoidable in terms of added heat resistive loss in controller electronics, internal wire resistance lost as heat throughout the connections from battery to controller and controller to battery and alternator to charger and charger back to batteries wire losses, additional inefficiency in battery losses of additional electrical charge conversion between mechanical and electrical energy due to batteries working increasingly less efficiently the higher the current demand is upon them, more loses in both motor and alternator {due to colliding field edge cancellations, stray Eddie current oscillations, heating of the metal coil cores internal electrical flow resistance, and air-gap magnetic flux variably wasted by radiating away not fully utilized for magnets to induce current in pickup coils or to counter magnetics from electrified coils as they move closer or rather away from each other and thee is always a bit of an air gap between rotating parts which dilutes the flux field} and loss to energy as mechanical fiction slowing down everything connected to the the drive shaft in resistive rotation loss due to metal to metal contact drag and heating in bearings, motive force lost inefficiently to mechanical vibration, any light grab from barely touching imperfectly functioning disk breaking system alignment or calibration (pads skating on rotors which breaks are not technically engaged but the driver), tire to road traction loss to.road gripping and tire heating, and any acting wind drag upon the car creating additional resistance counter to any force exerted in the drive train to propel the car though force backfeed and additional friction put to tires by increased counterforce, etc.)
Now as for charging the 12V battery instead of the mains by using a DC DC converter, it does remove the negative feedback loop because any increased drain on the 12V battery will not cause additional drain upon that battery because its charge is not used to charge itself thus not requiring higher usage from this battery to cover higher charging needed under higher usage an avoids all the mechanical and electric to mechanical and back conversion penalties additionally incurred if it was charged using an alternator. The DC DC converter penalty only involves one loss through transformer inefficiency and some electronic heat and much less wire resistance heating loss and no mechanical friction losses. You will loose far less power charging 12V directly electrically from the drive batteries.
You will always loose some energy moving power from any system to any another, including directly from drive batteries to 12V battery (for example) through the resistance losses of the wiring and internal inefficiencies of converting chemically stored electricity to raw electrical energy from the main batteries (heat loss) and the opposite converting electrical energy back to chemically stored charge (heat loss) in the 12V battery and the step-down voltage and regulator and charge electronics (heat losses, and step-down voltage transformer magnetic field loss inefficiencies moving power through the air or metal core from one coil to another). Those losses are much less though than if you tried to pull the addition of charging power from a mechanically connected alternator on the drive train. True the alternator would avoid small penalties of a DCDC converter (which are only like 95% efficient at best) but it adds much large additional electronics heat losses and mechanical heat losses due to the linked resistive friction of tires, superficial imperfections and friction between the bearings and their housings, mechanical drive transmission inefficiency (if one is used) and all additional vibrational and rotational friction and heat losses to U joints/differentials and mechanical matings of the motor to the drivetrain and drive line to wheels, wheel hubs if even slightly imperfect (off center or slight difference in angle of rotation between mated couplings), imperfectly balanced or align tires causing more rotational resistance due to lost traction, tire heating and vibration losses, etc etc.. you get the picture. The more junk connected, the more you are going to lose no matter what so the less stuff is connected in a system, the less your losses will be. And any kind of feedback loops should be avoided because the will always become negative feedback loops because you never gain energy to inefficiency and complexities added, you only lose….
It seems as if you install alternators inside all four wheels and allow the alternators to spin feely whilst your foot is on the gas and provide what is it 3 amps per alternator so 12 amps (from the battery not the motor) when your foot is not on the “gas” then wouldn’t the rolling weight of a 2000 pound vehicle be enough for 4 120amp alternators to keep the batteries topped off indefinitely 🤔 or maybe I just have too much common sense to be taken seriously.
Seems to me that recharging the battery is certainly something that CAN be done and probably achieved already. There is no monetization in a car that can recharge itself. The oil/energy industry is literally the backbone of the global economy. I think we we could never expect a manufacturer to offer that, however, we could hack it ourselves!
You could just use ac motors instead. If you invert the power to ac to power ac motors and wire in an electric generator (switch out the gears and lube for a near frictionless turn) and for every rotation the motor makes the generator will make 5 and you can use that energy to charge the battery. AC is way more efficient and easier to convert.
That’s still just a mechanical process of converting high voltage battery power to lower voltage 12V power for the accessory battery. Belts, gears, and any other mechanical connection is still going to be less efficient than simply using electronics (DC/DC Converter) to perform the same task.
You won’t see ANY commercially built electric vehicles that use an alternator or generator for charing the 12V system.
AC motor are great, and offer almost zero maintenance and regenerative braking, but they don’t give any special advantage to generators or alternators.
Can anyone please answer me..
What if we transform the wheel motion of ev to charge the battery by means of alternator?
What if we consider wheel motion in ev as ic engine for alternator to regenerate the electricity for charging battery?
Can it be done?
The electric motor in a modern EV already does EXACTLY THIS!
It’s called regenerative braking. When slowing down, the AC motor converts the energy of the car movement into electricity to charge the battery.
seems to me a combination of technologies can work. we can’t make perpetual energy but we can at least extend the range of an ev. Solar bonnets, solar roofs and air turbine at the front of the car (inside the bumper of course) and alternators inside the wheel, can extend the e.v range. Say from 300 to 320 miles. That 20 mile increase will increase the odds of finding a charger.
I understand that electrical to electrical energy will not work due to power demand being greater than output, but what about rotational to electrical energy? They use regenerative braking so why not belt driven at every axle during acceleration?
Regenerative braking SLOWS the car down.
It converts the kinetic energy (movement of the car) to charging the battery.
Battery charge goes up, but speed goes down.
It’s all about exchange.
Trying to charge the car from the wheels while accelerating would be the equivalent of hitting the gas and the brakes at the same time. It just ends up getting you nowhere fast.
Solar would work, as it is bringing in energy from external to the system (sun shining on solar panels.)
Other things, like alternators on the wheels, are just trying to rob the vehicle of the energy needed to push it down the road. Likewise, wind turbines make it HARDER to push a car down the road. (Wind turbines while PARKED would work, although impractical..)
make the wheels the alternators
Why have an accessory battery, why not use the DC-DC converter to directly feed the accessories?
You still need power to turn on the system in the first place. A battery is handy stored power for doing that.
12V battery is also useful for things like having the radio on when the car is off.
Lastly, if there is an issue with the DC/DC converter, the battery would still carry things through, whereas without one, everything would simply shut down. (I had that happen once on my DIY electric motorcycle when I ran it with ONLY a DC/DC and NO 12V battery.)
From my experience…. It will only be possible when there are two sets of battery packs… The alternator(s) will be charging the idle battery pack…. Note:batteries when charging has lesser internal resistance, that won’t have much effect on the back EMF of the alternator, but if the alternator is to get in the way of the driving pack,the resistance will be much for the alternator……building a long lasting range of ev is not impossible….Elon Musks is aware of what am saying
I’m wanting to hybridize an old 1990 Ford stripped-chassis ambulance. I want to keep the whole rear-wheel-driven 7.3L diesel oil burner, but add two forklift motors — One to each of the two front wheels.
I’m down with the laws of thermodynamics, don’t believe in Santa, unicorns, or anything approaching “over-unity.” But I did imagine that I’d be keeping the alternator for use while the diesel was running, with any generated surplus going to the EV cell battery bank. But now, having read this article, I’m wondering if it wouldn’t be better to switch the alternator to an old-school, pre-alternator generator. I wouldn’t think I’d be suffering from the inefficiencies of generators, because I’m likely to always have cells with room to take any of the surplus power, right? And for clarity, The vehicle would either two large banks, or three. If two: one of several deep-cycle marine 12V in parallel, one ~300v EV bank. If three: (2) 900CCA lead-acid 12v start batteries (2 @ 750CCA is factory spec), several deep-cycle for RV functionality, same EV bank.
Anyway, I love your project, your readily sharing of information, and your thoughts on this conversion, if you have any. Thanks!
You certainly could use the power from a diesel engine to charge an EV battery pack while driving on the diesel. For example, you could drive in town on just electric only (with the engine off) and then on the freeway, run on the engine and slowly recharge the EV battery pack. Of course, the trade off will be that you will get worse fuel economy while creating the extra energy for charging the battery.
I’m assuming that the ambulance is NOT already four-wheel-drive. It is not easy to simply “add a forklift motor” to a front wheel. You need great reduction and a drive-shaft.
Another alternative way to do it would be to put a lower-speed, high-torque electric motor IN the driveshaft with the power of the engine mechanically passed through the motor.
It’s 100% possible. But these companies cannot produce products the government can’t personally tax. Sure put them out and see how fast driving tax or more tolls becomes their cash grab.
An electric car was made that will run forever with a constant charge,will never be seen by the public.Electricty was created to charge the public for it,s use,and so will the electric car.
An electric car was made that will run forever with a constant charge,will never be seen by the public.Electricty was created to charge the public for it,s use,and so will the electric car. How in hell did we go to the moon and back and not be able to make a system that requires no way to make additional energy to run a car. I don,t believe that for one minute. It,s all about money and always will be.
I do see the math behind energy in and out. But I would argue that if the frame itself was designed with alternators to house the axles independently then the rotation of the axles would freely be making the extra power needed for regeneration under load. Simple mathematics and some current transducers should suffice for the main computer to determine heat loss and then switch to another set of fresh batteries. If you constantly maintain a thermal load at the current circuit load then you should be able to maintain battery integrity while providing performance. Without my own tests I can not confirm whether the loss would be to much for the amount of energy to recover. Either way then a hybrid would simply be more efficient for the meantime under the current topic and electric cars are a mute point. I believe however there is a way under motion to harness extra power. I would need some prototypes and time to test some theories before I could confirm.
No I’m sorry, but you are wrong and I’m going to prove it, as everybody else mentioned above, there are gains to using an alternator, think of an electric motor starting from a stopped position under load, it will draw tremendous amounts of current to get up to rated speed then current will stabilize and balance out. Now think of a motor with no load attached. Less work requires less current. If the motors already operating a load, then you attach a device able to produce power with minimal resistance, it’s no different from running a non loaded motor. Now if it is electrical interference that we are worried about. Then configure the vehicle with 2 batteries and a control routine to load one while the other is charging (a tap changer if you will). Also if your already using ac motors, then a 9 lead dual voltage motor can be used as an alternator alike. When wired for high voltage and under load you can run a smaller load on the low voltage windings. There are definitely ways to keep these things running like gasoline engines, it just takes an industrial electrician and a couple ideas and we can get it done. I’m on the job lol
I believe it’s possible to have a number of Dynamo’s (alternators) generating electricity from the rotation of the car wheels (axles) i.e independent from the motor. I once had a bicycle with a Dynamo that powered lights through the rotation of the real wheel.
You don’t need a rocket science degree to know that this is possible.
I’m sure the Admin is paid a lump sum to deceive us all.
I see you @John B. Hite September 11, 2020 at 4:40 pm
I understand that electrical to electrical energy will not work due to power demand being greater than output, but what about rotational to electrical energy? They use regenerative braking so why not belt driven at every axle during acceleration?
If the wheels are spinning INDEPENDENTLY of the motor, then YES you CAN generate energy that way.
However, for the wheels to spin independent of the motor, you either need to be going down hill or slowing to a stop!
Bicycles that had a dynamo on them to power a light were not powered by the rotation of the wheel, they were powered by the bicyclist PEDALING the bike. Pedaling the bike with the light on is MORE work than pedaling with it off.
The Admin is NOT paid a lump sum to deceive anyone. No idea who would be paying anyways!
The reason regenerative braking works is that it converts the motion of driving the car forward into charging the battery. The car slows down because the power is going into charging the battery. Trying to charge the car by driving forward while regenerative braking would essentially be like trying to drive a gas car with the parking brake on. Nothing good would come of it.
The following YouTube links explain the whole theory, it’s just a matter of scaling up the technology for a car or anything that rotates:
https://youtu.be/WhrE0BnM1qU
https://youtu.be/M0DKjnAeIq8
https://youtu.be/OhjA4K3rT_w
https://youtu.be/8qv5PxIYY1c
Dynamos work fine for powering a bike light. The energy comes from the bicyclists legs.
But if you were trying to use a battery to power a light, it’s much more efficient to just do it directly than to use a battery to spin a motor to spin a generator to make electricity for a light.
This is the same reason that electric cars don’t have alternators.
The engine turns into an alternator when deceleration. It should be called regenerative deceleration to make it less confusing. With using the wording regenerative braking it makes it seem like the brakes are create the energy to go back into the car. Also is magnetic braking possible? If you have coils over the rotors that create a magnetic field around the rotors would it slow down? Could it be modulated using a break which tells a junction box how much volts to send through the coil depending on how much force is being applied to the brake?
I’m tired of people saying an alternator setup wouldn’t really work. You put four 250 amp alternators in a Tesla, one on each drive axle or drive axle running through each or if the rpms wouldn’t be enough, put a pulley on each with a better ratio for maximum output at lower speeds. If you can run a house off car batteries with an inverter, you can keep a battery powered car charged while it drives. Stop making excuses and build it! There are magnetic generators being built that run infinitely on their own once you start them and I’ve also seen a modified alternator run an electric motor that supplied the alternator with power to keep it running but it had to be manually started at first. Another thing, alternators put out alternating current before they put ouyout direct current so something could even be done with that. Too many excuses and not enough trying. We are Ameri-cans not Ameri-cants!
Magnetic braking IS possible and is actually used in a number of industries. For example, I know that there are some elevators which essentially use an electric generator, with the output just run to a heavy heating element as a load. That creates the electro-magnetic resistance which then slows the elevator descent.
There’s also something known as “plug braking”, which is where polarity is reversed inside an electric motor to oppose the mechanical force. Very common on machines like forklifts. Of course, the energy has to go somewhere, so typically, it is converted to heat and dissapated in the motor.
It’s also completely possible to use reversing magnetic fields to INTENTIONALLY cause heat. That’s basically how induction heaters work.
The important thing to always remember is that energy is never created or destroyed – it just changes from one form to another. In the case of regenerative braking, kinetic energy (movement) is exchanged for electrical energy (charging the battery).
There’s no such thing as a free lunch! But cleverly making use of this, we can do some pretty cool things!
In the example of the house with an inverter, you could make AC power from the inverter and batteries, but you would NOT also be able to power a battery charger from it to CHARGE those same batteries. You can’t get out of a system more than you put in to it. And there are always losses (usually heat) when converting from one form of energy to another. So, even if you DID use batteries to run a charger (whether an AC battery charger or alternators on the wheels of an electric car) to then charge those batteries, you would always end up with LESS energy than you did before.
Climatologists agree that if we haven’t managed to keep the mean global temperature from increasing more than 1.5 degrees Celsius by 2050 the Earth is in big trouble. There are approximately 1.3 billion internal combustion vehicles on the road right now worldwide. These vehicles spew about 25% of the total carbon emissions into the atmosphere each year. Self charging electric vehicles could basically eliminate this 25% of fossil fuel emissions. This technology is not complicated. Your bloggers have come up with many logical ways this could be done. I have a few ideas also, including attaching an extra wheel to the frame to spin a 110/220 volt belt driven alternator or tow a little trailer with an alternator driven by a wheel; attach a small wind turbine somewhere on the vehicle. Primitive but the point is simply to spin a 110/220 volt alternator to recharge the vehicle’s drive batteries while the vehicle is in motion. This is not perpetual motion, not regenerative braking, not a power drain. It’s a separate circuit entirely, no different than plugging the EV in at home. This is so obvious, I have no doubt that this has been considered by the tall foreheads in the EV industry and I also have no doubt that Tesla and others have been warned by greedy energy providers. “You can have the EV market but hands off fossil fuels!”. It’s a disgrace, that in this day and age of catastrophic global warming this has not been implemented and I would like to challenge EV manufacturers and engineers everywhere to step up the the plate and do the right thing.
The big difference is that when you charge an EV at home, the energy is coming from somewhere else – typically a power plant on the other end of some electric lines. If you are trying to charge a car by having a wheel making an alternator spin, it’s like driving with a parking brake on. Energy has to come from somewhere.
It simply can NOT come from the car and then somehow make MORE energy than it is draining.
Ben N. ; The energy is not coming from the car. Picture a belt driven 110 volt alternator mounted in the storage well of an EV. The belt is connected to a pulley which is attached to a wheel mounted under the vehicle. The pulleys are sized to spin the alternator at about 3600 rpm at an average speed of 60 mph. The car’s charging cord is plugged into the alternator–just like in your garage at home or at a charging station. I know there are minor issues with this particular scenario but nothing that couldn’t be overcome by engineers. The point is it is certainly possible to continuously charge an EV’s drive battery pack while the vehicle is in motion.
So where is the energy coming from?
Alternators do NOT make energy for free. They convert mechanical rotary motion energy into electrical energy. In a gas car, if an alternator is running, your engine has to work harder and burn more fuel.
If an alternator was mechanically connected to a wheel, it would provide more resistance, and that wheel would slow down. To avoid slowing down, the car would need to use MORE energy than it would without the alternator connected.
If the output of an alternator mounted to the wheel was fed to the charger of an electric car, you COULD feed power to the car’s propulsion battery, but you would also need to use even more power to push the car down the road.
The result would be a net discharge of the battery rather than a charge.
Hydrogen fuel is the answered my American friends no need for self charging and cleaner energy toboot
Hi there Admin,
(College Guy, Lit Major, No knowledge of cars, just curious about the theory of all this, and in want of conversation. )
So the energy made by the wheels spinning is not as powerful as the energy spinning the wheels. That energy cannot be recreated in the action, no matter how complex the contraption.
Fossil fuels seem like a quickest energy solution, with wind/gas/hydro all being slower, acre after acre of equipment running around the clock to produce the same amount of energy. They forget, or do not know, that the creation of oil has been a millennia long process of living, gaining energy, dying, and compressing, for eons. There is no comparison.
All that these people are concerned with is spinning their wheels. I hope one day someone cracks the code for perpetual energy, it certainly wont be one of these people.
Now for my little theory question. A friend of mine talks my ear off about some salt and glass battery made by John B. Goodenough. Sounds nifty. Any grit to this?