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Mechman High-Output Alternator - All Amp'd Up

Posted in How To on April 17, 2004
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The buildup of a four-wheel adventure vehicle will probably include the installation of trail and performance accessories such as a recovery winch, high intensity lights, a 1,000 watt stereo system, a compressor, some more lights, and a portable freezer fridge. We have one important suggestion for you, though: Don't forget to upgrade your charging system. If you plan on adding these amp guzzling accessories, it's a good idea to bolt in a high-output alternator.

Mechman in Hesperia, California, builds some of the most powerful and dependable alternators available. The alternators are so dependable, you can find them on tough off-road machines, competition vehicles, emergency fleet vehicles, and top-secret military spy planes. The ProPower alternators are available with 145- to 225-amp outputs. The voltage output of an alternator is controlled by the voltage regulator, and usually stays between a constant 13-1/2 to 14-1/2 volts. With more than 15 volts, there is a risk of damage to the vehicle's electrical system; less than 13-1/2 volts, and things may stop working or being charged. These problems usually occur when the alternator's regulator fails. Amperage output, however, can greatly vary, and the more amperage, the more power. Amperage is the volume of electrons in the current flow, which is measured in units known as amperes or amps.

So, imagine a situation where you're winching at night with your lights on. Is your battery being charged? The amperage output of your factory Jeep alternator (through the years) is anywhere from 37-78 amps; the GM is 42-150 amps; the Toyota is 40-110 amps; and the Ford is 40-135 amps. These are SAE amperage ratings, which are tested cold (when the vehicle is first fired up), and the amperage output of an alternator always drops when the alternator is running at operating temperatures (hot rated).

Although a high-output alternator is installed on a vehicle, it should not cause concern. The regulator and the load placed on the alternator determines the amperage output of the alternator. If you place a 10-amp load on an alternator, that's all it will put out. If you place a 100-amp load on an alternator, then that's what it will put out. The regulator will not allow the alternator to cause a problem in the electrical system.

Mechman's alternators are always hot rated and test in at 145-225 amps, depending on vehicle make and customer preference. The amperage output for our project Toyota alternator tested at 175 hot-rated amps and 215 cold amps. This is twice the 60-amp rating (cold) of the '85 Toyota factory alternator and should give us more than enough power out on the trail to use our electrically draining accessories and charge the battery.

Our Mechman high-output alternator tested at 175 amps (hot). This is a major increase in amperage compared with the factory Toyota alternator, which has a rating of 60 amps (cold). Our Mechman high-output alternator tested at 175 amps (hot). This is a major increase in amperage compared with the factory Toyota alternator, which has a rating of 60 amps (cold).
These are the major components of the alternator. The following images explain what each high-quality component's function is. These are the major components of the alternator. The following images explain what each high-quality component's function is.
Alternators are basically three-phase AC devices; the rectifier (shown) changes the AC to a more usable DC output. It has to handle the full output of the alternator and therefore must be manufactured using extremely high quality components. Note the large phosphor bronze stud. Alternators are basically three-phase AC devices; the rectifier (shown) changes the AC to a more usable DC output. It has to handle the full output of the alternator and therefore must be manufactured using extremely high quality components. Note the large phosphor bronze stud.
When the rotor turns, it induces a magnetic field into the stator (shown). This field produces a three-phase AC output that is connected to the rectifier. The stator/rotor clearance must be held to tight tolerance in order to obtain the most output from the alternator. It must also be large enough with enough copper wire to give good output from idle and should be able to give maximum output around 2,000 engine rpm. When the rotor turns, it induces a magnetic field into the stator (shown). This field produces a three-phase AC output that is connected to the rectifier. The stator/rotor clearance must be held to tight tolerance in order to obtain the most output from the alternator. It must also be large enough with enough copper wire to give good output from idle and should be able to give maximum output around 2,000 engine rpm.
The drive end housing is made from aluminum and supports most of the alternator. A new alternator should be fabricated using new housings of high quality material. The drive end housing is made from aluminum and supports most of the alternator. A new alternator should be fabricated using new housings of high quality material.
The front or drive end bearing takes most of the side load imposed by the "V" or serpentine belt. The rear or slip ring end bearing provides for rear support and is designed to move in the rear housing to compensate for movements caused by temperature variations. Note the clutch rings on the end bearing. The bearings especially have to be of extremely high quality as the alternator rotor can spin to very high rpms when the engine revs up. The front or drive end bearing takes most of the side load imposed by the "V" or serpentine belt. The rear or slip ring end bearing provides for rear support and is designed to move in the rear housing to compensate for movements caused by temperature variations. Note the clutch rings on the end bearing. The bearings especially have to be of extremely high quality as the alternator rotor can spin to very high rpms when the engine revs up.
Power is applied to the rotor coil from the voltage regulator through the brushes to the slip rings. The rotor produces a magnetic field that is induced into the stator, which in turn provides the output through the bridge rectifier. The regulator controls the output of the alternator by varying the rotor energy. Power is applied to the rotor coil from the voltage regulator through the brushes to the slip rings. The rotor produces a magnetic field that is induced into the stator, which in turn provides the output through the bridge rectifier. The regulator controls the output of the alternator by varying the rotor energy.
The voltage regulator varies the energy going to the regulator according to the needs of the vehicle. It senses the voltage and sends the proper signal to the alternator rotor approximately 300 times per second, which instantly regulates the alternator. The voltage regulator varies the energy going to the regulator according to the needs of the vehicle. It senses the voltage and sends the proper signal to the alternator rotor approximately 300 times per second, which instantly regulates the alternator.
This is the comparison between the ProPower (left) alternator and the Toyota alternator (right). The ProPower is designed after a Ford-style alternator housing, which is larger in size. This housing usually has more ventilation for better heat dissipation, providing for a longer life. Mechman points out that the life of the alternators should be 200,000 miles plus, and the company has units that last well beyond that. This is the comparison between the ProPower (left) alternator and the Toyota alternator (right). The ProPower is designed after a Ford-style alternator housing, which is larger in size. This housing usually has more ventilation for better heat dissipation, providing for a longer life. Mechman points out that the life of the alternators should be 200,000 miles plus, and the company has units that last well beyond that.
Even with the larger housing, the new alternator easily fits into the tight engine compartment of our project Toyota. Mechman has the bracketry available to fit just about any vehicle. Even with the larger housing, the new alternator easily fits into the tight engine compartment of our project Toyota. Mechman has the bracketry available to fit just about any vehicle.

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