Hi Aaron,
I see that you first posted a link to Zena products in Sept 2010 (post #15531). I would have figured that you would have moved further along by now.
This concept was first brought up in this group back in 2004, here's a brief excerpt of a response from Matt (post #2943) "These look like modified automotive alternators. They use a PWM control to adjust the welding current and call it "high frequency DC" wich is kind of a false statement. The output from a speed controller like a curtis is similar. It is DC but it is just switched on and off really fast at a high freq...."
Myles commented on the same concept in Oct 2006 (post #6072). Here's that post. "Watch out for snake oil. High electrical output power is only one factor to consider in engineering a solution to the problem to generating electricity from an IC enging. Equally or more important is efficiency. Otherwise, why bother? Most alternators are not very efficient (roughly 50%) and unless you provide cooling or spin them fast, they will get hot. You will pay hundreds for an efficient one (e.g. a Bosch), which still won't hit the efficiency of a quality permanent magnet DC motor used as a generator. For low speed applications, don't even consider an alternator. Note that at your high output alternator site ( http://www.zena.net/htdocs/alternators/mar_alt.shtml#Top ) they mention the word efficiency only once. Efficiency is not what they are selling and I couldn't find mention of it except to point out that inverters can be 95% efficient. DC Permanent Magnet brush motors like those made by Leeson, PMG, LEMCO and others offer the ability to generate high currents at relatively high efficiency----figure on 80%+. If low speed generation is important, forget the alternator if you need even 30amps...you won't even be able to keep it cool and you'll be losing 50% inheat---e.g. 360watts of heat to get 360watts into the battery.
-MT"
Even though a number of people in this group have discussed how they would make this work over the last eight years, nobody has reported that they actually built one and that it worked. However, nobody has reported that they built one and it didn't work....
Of course, there's a first time for everything. Since you've figured out a fairly inexpensive configuration, I think that you should give it a try. If it works, you will have made a huge leap forward for electric boaters around the world.
My impression is that your proposed system will be inefficient, noisy and hot. I would love to be proved wrong.
Good luck.
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "akenai" <akenai@...> wrote:
>
> I was looking at a 10 hp air cooled diesel motor that I could use to power a Zena brand generator. Thinking lower cost than anything else I have been able to find in water coold packages. I think the Zena DC unit would be better than an AC and converting back to dc for charging batteries.
> Anyone care give pros and cons ?
>
>
> http://www.zena.net/htdocs/alternators/Build_a_Genset.shtml#Top
>
> http://www.ebay.com/itm/New-Apollo-10HP-Single-cylinder-air-cooled-diesel-engine-/120826011983?pt=LH_DefaultDomain_0&hash=item1c21caa14f
>
> Aaron
>
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