Evinrude Alternator Output

Electrical and electronic topics for small boats
alloyboy
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Evinrude Alternator Output

Postby alloyboy » Tue Jan 05, 2016 3:55 pm

The Evinrude website offers the following information: "133 Amps Total Output/ 50 Amps Net Dedicated." [This was later clarified to be in reference to the alternator specifications for an Evinrude E-TEC G2 engine--jimh]

Is this saying 50 amps dedicated to run the motor with 83 amps being available to charge a battery? Or, is it vice versa? I think the former, [but seeks other opinions].

Rbrown
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Re: Evinrude Alternator Output

Postby Rbrown » Tue Jan 05, 2016 8:32 pm

It means that 50 Amperes are dedicated to charging the battery.

jimh
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Re: Evinrude Alternator Output

Postby jimh » Tue Jan 05, 2016 9:48 pm

So far no Evinrude engine has been mentioned. For most of the Evinrude E-TEC first generation engines in the V6 3.3-liter platform, the website says: "Alternator output 133 Amps Total Output / 50 Amps Net Dedicated"

My inference has always been that this means there are 50-Amperes of electrical current output, that is, extra electrical current not used by the engine and available to be used for running other electrical loads in the attached 12-Volt electrical system.

The amount of current that could be absorbed as charging current by an attached battery is really not going to be fixed at 50-Amperes. The charging current going into a battery will be determined by the battery's state of charge, its terminal voltage, its temperature, the internal resistance of the battery, the resistance of the primary power wiring, and the alternator output voltage.

alloyboy
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Re: Evinrude Alternator Output

Postby alloyboy » Wed Jan 06, 2016 9:57 am

Thanks. My question was with respect to the G2 Evinrude 250/300 models. 50-Amperes available to charge a battery, if needed, it is.

Anyone care to guess why the total output of the [alternator] is stated if, from a user's standpoint, it is mostly irrelevant? Or is it relevant?

jimh
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Re: Evinrude Alternator Output

Postby jimh » Wed Jan 06, 2016 11:08 am

I have never given any thought to why Evinrude mentions to total electrical power output of their alternator. Since you raise this unusual question, my only thought is Evinrude mentions the total output of the alternator in order to have a specification that is similar to other manufacturers of outboard engines.

How important is the total electrical power of the alternator of the Evinrude E-TEC G2 engine compared to the available surplus power for other uses in your decision to buy this engine? An electrical load on the engine of 50-Amperes seems like a very high power loading in a small boat.

The Evinrude E-TEC engines use a permanent magnet alternator (PMA). A PMA is the most efficient alternator type. See my article about permanent magnet alternators for some more information.

In Evinrude E-TEC G2 engine the alternator design is a bit different than in the first-generation E-TEC engines. The rectifier and regulator components for the alternator are no longer encapsulate in the engine management module (EMM). They are now housed in their own separate assembly. I consider this design to be an improved design compared to the first-generation E-TEC alternator. Having the alternator rectifier-regulator as a separate assembly allows it to be serviced or replaced separately from the EMM.

alloyboy
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Re: Evinrude Alternator Output

Postby alloyboy » Wed Jan 06, 2016 1:12 pm

jimh wrote:I have never given any thought to why Evinrude mentions to total electrical power output of their alternator. Since you raise this unusual question, my only thought is Evinrude mentions the total output of the alternator in order to have a specification that is similar to other manufacturers of outboard engines.


That is probably a good thought. Most other motors provide the total output of the generator while remaining somewhat silent as to how much is available to the user. Yamaha brags for instance about having a 70 amp output with the Offshore model but what they don't state is that only 55 amperes are available as output from the motor. They use the term "Net Capability" so perhaps I should have correlated that to what BRP was saying.

Now I am curious as to why you say "A PMA is the most efficient alternator type." What I call a PMG (Permanent Magnet Generator) is typically making all of the power of which it is capable of making at a given engine RPM. Power that is not desired/needed can be wasted in the form of heat. Is this not the type that the G2 PMG uses? I would have thought that a belt driven alternator would be more efficient in that it is only making the power needed, based on what the electrical loads happen to be at any given time.

jimh
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Re: Evinrude Alternator Output

Postby jimh » Wed Jan 06, 2016 2:36 pm

The PMA is driven from the flywheel directly, so no losses in pulleys and belts. There is no exciting current needed so it works without need to have a battery. Did you read my article? It explains all of this. The more modern automotive alternators are using PMA techniques. Wind-driven alternators are almost always a PMA. Efficiency is important in those applications.

alloyboy
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Re: Evinrude Alternator Output

Postby alloyboy » Wed Jan 06, 2016 5:12 pm

jimh wrote:The PMA is driven from the flywheel directly, so no losses in pulleys and belts. There is no exciting current needed so it works without need to have a battery. Did you read my article? It explains all of this. The more modern automotive alternators are using PMA techniques. Wind-driven alternators are almost always a PMA. Efficiency is important in those applications.


Link to the article please? Can't find it.

jimh
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Re: Evinrude Alternator Output

Postby jimh » Wed Jan 06, 2016 5:55 pm

I mentioned the PMA article in my earlier reply:

See my article about permanent magnet alternators for some more information.


The forum uses hypertext. Hypertext elements are distinguished by the change in color (blue) and the underling of the text. Clicking on hypertext will take you to the linked resource. In the above, the words "permanent magnet alternators" are hypertext and are linked to the article mentioned by the sentence.

jimh
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Re: Evinrude Alternator Output

Postby jimh » Wed Jan 06, 2016 6:14 pm

The permanent magnet alternator (PMA) in the Evinrude E-TEC uses a rather intriguing circuit to improve the alternator output current at low and high engine speeds. The alternator has three coil windings. At lower engine speeds the three windings are connected in series so their combined voltage output is high and the alternator can produce useful electrical power at low engine speeds. When engine speeds increase, the three coils are switched electronically into a parallel arrangement, as each coil is now producing sufficient voltage. This trebles the current output. When alternator rotation speed is very high, another effect, saturation of the coils, causes the output voltage to decrease, so the three coils are switched back to a series configuration to sustain better output voltage. This switching is all done with solid-state devices and a very crafty circuit design.

The primary voltage of the E-TEC power generation by its alternator is 55-Volts. The 55-Volt bus runs most of the engine high-current consumption devices. The 55-Volt bus is then regulated down to 12-Volts to provide power for the engine 12-Volt devices and to provide power to external 12-Volt loads. The voltage conversion is accomplished with pulse-width modulation techniques and is very efficient, so not much energy is lost in the conversion. The 12-Volt output is also voltage regulated. Since it derives from the 55-Volt bus, the conversion to 12-Volts is easily able to accommodate a wide range of input voltages while maintaining a regulated output.

jimh
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Re: Evinrude Alternator Output

Postby jimh » Wed Jan 06, 2016 6:43 pm

Non-permanent-magnet alternators rely on a exciting current to be supplied by a storage battery. To develop sufficient output at low engine speeds the alternator is usually turned by a belt and pulley arrangement so its rotation speed is several times greater than the engine speed. In automotive use a transmission usually changes the gearing for the engine as vehicle speed increases, so that at normal driving speeds the engine crankshaft rotation speed is down to a fast idle, about 1,800-RPM. In marine engines, there is no gearing, so at cruising speeds the engine is running at a crankshaft speed of perhaps 4,000-RPM. Since the alternator is geared-up in its rotation speed, the alternator is then turning at extremely high speeds, perhaps 10,000-RPM. This high speed puts added wear on the bearings and other moving components. Of course, in a conventional alternator there is a moving coil winding, and there must be brushes to carry the current. The brushes also have to work at these very high rotational speeds in vehicle-type alternators that have been adapted marine engines.

The belt and pulley arrangement also imposes side loading on the engine crankshaft bearings and the alternator input shaft bearings. This also increases wear.