T-Pain Is On A Boat: Re: [Electric Boats] Re: Planning Cal 2-27 conversion, advice needed

Friday, November 16, 2012

Re: [Electric Boats] Re: Planning Cal 2-27 conversion, advice needed

Yes.

Running at wot (wide open throttle) will require a generator and power converters rated appropriately. WFCO makes 35amp units that have a foldback voltage feature. You pull more than the rated capacity, and their output voltage will decrease proportional the the load, until the converter shuts down.

If you're running a Honda "2kw" genny, it can maintain a continuous output of 1.8kw (reference from memory) continuously. This means you can run your system at PARTIAL throttle only, basically drawing 1.8kw max. Buy a set of 95a WFCO converters, and a much larger genny, or two paralleled smaller ones, and you'll be able to run more power.

Be careful, however. Running any system at 100% capacity is a fool's errand. Build headroom into your design, and plan on over-spec'ing your components. I use Kelly controllers turned down to 60%, for example, to build a more stable product. Yes, you can pull 35a out of a unit rated as such, but why push the limits. You don't shift your car at redline, so why treat your boat motor system any differently?

Sailboats can motor at low speed very efficiently. if you plan on extended motoring, get a generator at least 20% larger than required by the power converters. Size the converters at least 20% over your motor load.

Be Well,

Arby

On Nov 15, 2012, at 11:05 PM, "kotyara73" <krollokot@gmail.com> wrote:

Wouldn't 35amps x 4 overload the Honda? if the batteries are drawing all they can, that wouldn't leave much room for the motor. Or am I misunderstanding all this?

--- In electricboats@yahoogroups.com, Arby Bernt <arbybernt@...> wrote:
>
> Go with the WFCO units. Each unit tends a single battery, 35a continuous output with three stage charging. Dozens installed, not a single failure (except one installed in reverse polarity, don't go there...)
>
> Be Well,
> Arby
>
> On Nov 15, 2012, at 8:28 PM, "kotyara73" <krollokot@...> wrote:
>
> > One thing that I never really gave much thought to is the battery charger. But now, having read the recent discussions on the topic, I started doing some more research on it and now I more confused than ever. So, I'd like some help choosing the right unit. Battery bank will likely be 4x100-150Ah AGMs feeding ME907/Sevcon kit. Here're the requirements (or at least draft requirements :)
> >
> > 1. Has to be able to work with the Honda genny. I gather that means drawing between 13.5 and 14 amps from it, which should result in ~25amp on DC side.
> >
> > 2. Has to be able to supply that power to the motor when the batteries are low. Otherwise, what's the point of a backup genny?
> >
> > 3. 4-bank 12v charger so as not to worry about battery imbalance? Not too sure about this one, but it seems reasonable.
> >
> > 4. Has to be robust enough to be left plugged in for a couple of weeks and keep the batteries happy. There won't be any other load at this time.
> >
> > 5. Solid state rather than transformer, for efficiency.
> >
> > 6. Not too expensive. I'm figuring $500 tops, but obviously the lower the better.
> >
> > Here're the options that I've gleaned from discussions in this group:
> >
> > 1. Elcon. Sounds like the right unit (except for being serial), but it's $750...
> >
> > 2. QuickCharge. Transformer, doesn't sound very robust.
> >
> > 3. DualPro. Issues with motor load while charging.
> >
> > 4. Zhivan. Not sure what to think of this one.
> >
> > 5. ProMariner. Saw it mentioned once. Sounds good, but I can't figure out their specs. When they say it's 4-bank 60Amps 12/24/36/48, what exactly do the amps refer to? They don't list their input amp draw either.
> >
> > 6. 4xWFCO converters. Arby's special :) Seems like a good solution, but single unit would be nicer. They also sell main boards, would it be difficult to put four of them in a single enclosure?
> >
> > So, as I said, I'm confused. What say you? What would be the best option?
> >
> >
>