How to Turn a Car Alternator into a Generator

Updated On: April 24, 2021

If you have a dead old car lying around in your garage, consider turning its alternator into a generator and produce backup energy. Since it’s collecting dust anyway, a valid choice would be to utilize its parts for something more useful, given the car doesn’t contain some other form of value.

Not all car alternators can be used as a generator. There are exceptions as alternators with a regulator are the ones that can take the responsibility of a generator. Alternators hide rather intriguing secrets. A typical alternator can convert energy from the internal combustion of an engine to electricity, which can be utilized to run other devices like electric motors. With the magnetic component that is supplied with the help of an electromagnet, devices like these usually take the form of three-phase alternators.

Car Alternator Into Generator

They come with a regulator and a rectifier pack, which helps convert AC voltage to 12V. The initial AC voltage is supposedly much higher and is converted to 12v for the electrical systems of a vehicle, like a car having three connections to the stator coils that appear to be usually wired to a delta configuration.

They are also connected to a set of brushes that are in pairs, helping supply coils through a set of rings for the rotor. Their capacity is high, and more importantly, they are commonly available in the market and second-hand markets while being surprisingly cheap, costing around 20$.

Scanning for vehicle alternator conversions will uncover an assortment of pages, how to dos, and aides and guides, a significant number that can be incredibly befuddling and over-complex.

To be specific, some suggestions do exist concerning the three stator and their connections, with exhortation like taking off each of the winding and utilizing rather difficult wiring designs. In light of the experience that we have of changing a significant number of alternators, this seems quite fuzzy. All the different models that have been changed have had a similar all set delta setup that required no reworking by any stretch of the imagination. Maybe it’s an ideal opportunity to give an original alternator conversion method and detonate any enduring myths while we’re grinding away. You will find three categories of alternators in the market. They include

  • External Voltage Regulator Type Alternator
  • Single Wire Connection type with Internal Regulator
  • Internal Regulator type with external Control Switch

External Voltage Regulator Type Alternator

This type of alternator does not contain a regulator inside. One must first connect it externally for it to function correctly. It controls the alternator’s field intensity, which in turn controls the output voltage and the current of the alternator. There are some disadvantages to using this type of alternator. It has to do with its connection. It’s more complicated as the regulator needs to be added separately, and its setup must be done correctly. This type of alternator costs less than the others listed in this article. Much like the models that have regulators inside, it requires a switch to turn it on and off. If not, the regulator part and alternator can discharge batteries even when it’s not supposed to be charging them.

Single wire connection type with the regulator

Single wire connection type alternators include internal regulators. They start producing power when their RPM of the input shaft reaches a minimum required speed. Times when it drops below the needed or preset speed, the supply stops. It does not require any switch, which is a significant advantage being able to isolate the alternator from the source(battery) to stop the alternator from taking power and draining the battery when it’s sitting idle. However, it comes with its own disadvantages. Single wire connection type alternators will start chagrining the battery as soon as the minimum RPM is reached, which will place a load on the engine. Sometimes a throttle is required through the range of minimum RPM, which ensures the motor does not bog down. This alternator also costs more but has an easy and simple connection method.

Internal type regulator with a control switch

This is another valid option that you can choose from. Alternators like these have internal voltage regulators requiring a switch that helps it turn on or off. The switch is external. The alternator can be switched off while the motor is still running, which is an advantage of internal regulator types that have external control switches. The power output stops as soon as the shutdown switch is pressed.

We realized that single wire configurations were not the best option for the application. We started up with the possibility of a modest brush-less engine because of the statements we made above. We decided to use an alternator from Ford Focus. So then, how can one approach to try and convert it? You will find that on the rear part of a decent alternator is generally a plastic residue. It’s a cover to protect against dust and harm, connected by a lot of screws and bolts. These gadgets are intended to be revamped so (maybe shockingly for a cutting-edge car part) they are typically simple for anyone to disassemble. Now, if you go ahead and remove the protective cover, you will discover regulators and brushes that are frequently found to be incorporated into a single unit. For the most part, given a Focus alternator is in use. In the case of the controller and brushes, a separate assembly of the rectifier is seen. 

There is frequently a bountiful amount of silicone sealant that should be removed; however, any nuts or screws that protect the controller can be undone pretty easily. Be very wary not to harm the brushes; you will be able to lift them clearly in a single piece. When you reach this point in the process, you can remove the rectifier unit. It’s better to utilize a side cutter because it’s much more convenient when you are about to take it out instead of attempting to evacuate it in one piece. You will soon recognize the three groups of thick copper wires originating from the enameled stator loops, separate the rectifier wires from them. In certain alternators, they’re fastened, but some other designs have them irritatingly welded in place. As you are reaching the end of this procedure, you should find yourself left with an exposed alternator at your hand having three sets of stator wires, an exposed shaft with two slip rings, and remaining parts of the rectifier, and the brush pack. Next, you need to remove the regulator’s circuitry, and you also need to preserve the shape of the assembly of the said regulator while you are at it.

Locate and preserve the connections of the brush where they associate with the regulator. Again, you will find a generous amount of silicone potting compound, and you need to get rid of it. You will see the regulator exposing itself eventually as you hack your way through the silicone. Typically, there is a hybrid circuitry on a ceramic/metal substrate. They have connections originating from molded plastics that surround them. You will be readily familiar with the pair of links that are meant for the brushes. Approach with care and unsolder them while you push out the circuit regulator.

At last, you should have an exposed alternator, a brush pack that doesn’t have a regulator circuit, and the dust cover. You need to solder three large gauge wires that are suitable to the three sets of stator wires. Cover them up, use heat-shrink. Use the solder to attach a pair of lighter wires to the brushes. The rectifier pack does not need any more modification or reassembling procedure. As such is the case, you may need to make a spacer. It will be used for a replacement to support the brush pack’s sides. You can make holes later in the cover for all the wires. At this point, you are pretty much done converting your alternator.

A brushless DC motor is just an AC motor with some electronics that convert DC to AC. The advantage over DC brushed motors is its efficiency, reliability, and convenience. One of the motivating factors for transforming automotive alternators into motors that produce electricity is that there is a whole range of brushless controllers for engines that can be owned for a low price. It will come in the form of ESC (electronic speed controllers). ESCs are generally used in some Chinese electric tricycles and bicycles.

They utilize a battery supply that is DC and produces three-phase AC energy that can power a delta-connected engine or motor. They work considerably well with alternators that are converted into electric motors. ESC typically has two modes. One of the modes is targeted for motors equipped with hall effect feedback sensors, and the second mode is for the ones that lack such sensors.

The alternator that we worked with did not have that sensor mind you. You will need a link that you accomplish by using a wire. Look at the instruction manual of your controller, and it should help you out. If you have a controller that has enough energy-supplying capabilities, you will find it reliable.

Alternatively, you can also make a minor modification to produce electricity from an alternator of your car by hooking it to a lawnmower motor. It will generate enough power to run small appliances, lights, and charge batteries.

Things you will need-

Car alternator, Alternator belt, 2-inch plywood sheet (4×6 feet), 1/4inch 8lag bolts, Power converter AC/DC, Power drill, Horizontal shaft lawnmower. Carbide bit ¼-inch, 4-inch steel pulley.

First, you will have to mount the alternator of your car to a ½ inch plywood sheet with ¼ inch steel lag bolts. Then you place the horizontal shaft of the lawnmower on the top of the same plywood. Go ahead and arrange the motor to mount it with a marker and remove the motor. Next, weld a 4-inch steel pulley to the lawnmower motor shaft, utilize ARC welder and the 3filler bar. If you are inexperienced with this matter, seek professional help after you have to place the lawnmower’s motor to the plywood again. Then, your car alternator belt has to be fitted around the alternator pulley and the pulley of the motor shaft. Until the belt is tight, slide the lawnmower to the side.  

Drill holes for mounting the lawnmower motor to the plywood with a 1/4-inch bit. Use 1/4-inch lag bolts to secure the motor to the plywood. Connect an AC/DC power converter to the alternator terminals. Hook up your battery or appliance to the AC/DC power converter. Power on the lawnmower motor to produce an electric current. Adjust the pulley’s size on the lawnmower motor shaft to create the proper speed for producing electricity with your particular combination of alternator and lawnmower engine. Belt size will vary depending on how far apart your alternator and engine shaft are positioned. This concludes the alternator conversion guide.

About Steven Smith

For the last 20 years, I have been working as a professional contractor in many construction projects. From my childhood, I love to work with different kinds of power tools. In my spare time, I love to do a different kind of DIY project. It gives me a kind of inner satisfaction.

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