Perhaps a 48 volt switchmode DC power unit would be best to get the efficiency . Another approach might be to run the motor via a rectifier/thyristor controller from the generator.
Chris S
--- In electricboats@yahoogroups.com, Mike <biankablog@...> wrote:
>
> Thinking about Steve's idea of a rectified 48 volts via the Honda generator. I'd have to dust off some old college textbooks but, it should be doable. Though I would probably use a full wave rectifier circuit with good filtering. Controllers can be pretty picky about what the DC voltage feeding into them looks like. Of course it would need to be properly fused. I'd also have to take a look at the efficiency too. There is probably a good reason why most power supplies today are switching power supplies as opposed to the transformer and diode rectifier circuits of the past. Though the transformer diode circuitry eliminates a lot of components and possible failure issues. For example accidently dropping a fuse onto a deenergized circuit board and shorting some componet of a Zivan battery charger causing it to be sent back for repair. Guess how I know?
> Â
> Capt. Mike
> http://biankablog.blogspot.com
> Â
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> Â
> --- On Mon, 9/27/10, Steve Dolan <sdolan@...> wrote:
>
>
> From: Steve Dolan <sdolan@...>
> Subject: RE: [Electric Boats] Re: motoring with a battery charger (Rectified?)
> To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
> Date: Monday, September 27, 2010, 6:57 PM
>
>
> Â
>
>
>
> Eric,
> That's why I suggested the rectified Honda 2000 as a platform.
> Output is 120V
> Rectify it to 48V and charge the batteries and run the Drive Motors.
> Unplug it from the rectifier and plug it into the charger for the batteries ONLY on the hook.
> Run the drills and other 120V stuff all you want right off the generator.
> You really don't need a specific 48V generator and the rectifier could be used for different voltage systems, the only thing that would change would be the Rectifier output based on an individual's needs.
>
> I have a 144v system set up this way. 240v/AC genset with a rectifier to 144v/DC to charge my batteries and power my motors. Then a Charger for shore charging. I just thought if it would work on a larger system why not a Honda based system and eliminate multiple chargers.
>
> Again just thinking.....
>
> Steve in Solomons, MD
>
> I can see where you're going with this, and it merits discussion. The main problem is a distinct lack of portable 48V generators on the market. The diesel generator alternatives are not much different in size, complexity and weight than the typical auxilliary diesel that would be installed in a 27'-32' sailboat, so they don't seem like effective choices for electric conversions of this size boat.
>
> The small Honda and Yamaha inverter generators are pretty cool devices, they have throttle feedback to adjust the fuel consumption under lighter loads, they're quiet and they produce fairly clean 115V AC. Of course, these features come at a price, they each run about $1000 for the 2kW models, a little less for the 1kW versions. The 2kW models are rated for 1600W continuous output, which could theoretically get you above 30A for a 48V system. Brian's report of 27A using an Elcon charger isn't too far from that target.
>
> I don't know how easy it would be to "highjack" the output of the inverter generators and run it at 48V nominal DC without removing the features that justified the extra cost. Adding circuitry on the finished output side of the wiring is effectively what plugging in an external charger is doing.
>
> I would guess that one could also find a less sophisticated small generator and re-wire it to 48V DC and cut half the upfront cost of the generator from the experiment.
>
> That said, for many of us, using an off-the-shelf generator and charger solution looks great. Both the charger and generator should come with a warranty and can be serviced by professional repair centers if needed. As Mike and Myles have stated before, the modularity of these solutions allows for upgrades without considerable re-engineering or reinvestments.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, Steve Dolan <sdolan@> wrote:
> >
> > I'm not sure if this is possible or even cheaper under the conditions you're all talking about but here is a question and maybe a suggestion.
> >
> > What about rectifying the voltage off the Generator to what ever you need. For the batteries and the motor(s). Let's say both the bank and the motors need 48V. The Genset would provide I believe (the Honda 2000?) around 24A? Sent to a common buss bar the batteries would be charged with anything the motor wasn't asked to use. The charger would be off line under this condition and as long as you didn't exceed the batteries maintenance charge input you could run it all day. On shore power the genset would be off. You could even wire the Genset to bypass the rectifier (a switch) to provide 120V.
> > I'm just throwing out a suggestion or an idea and not sure of the numbers I have used but I would guess this would have to be simpler and have less voltage drop since it's only 1 piece of equipment and more or less a direct connection to the motors and batteries from the genset.
> >
> > Am I way off on this??
> >
> > Steve in Solomons MD
> >
>
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