John,
I stumbled on this recently, http://sfbay.
Not exactly local for you but a great unit. I used one on an Ericson 23 for a few years.
Mark
--- In electricboats@
>
> Thanks Eric
>
> Thanks for ringing in. I've never dealt with AGM batteries, but have read
> about non-damaging discharge rates of 70 and even 80 percent. I always
> thought wet-cell deep cycle batteries were considerably less dischargable
> than 60 percent before potential damage might occur.
>
> I'm lucky in that I have no need of speed, have a relatively short run to
> open water and a boat that seems to move with little effort. In years past,
> I had a sailboat that totaled almost 2700 pound total displacement and moved
> quite adequately with a MinnKota 42 pound thrust motor and one of those
> little almost flat-pitched propellers. I actually favored this motor to a
> 5-1/2 HP gasoline outboard, which I finally gave away. I used the 42 pounder
> for 11-12 years and was very happy with it . . . even in headwind.
>
> ANYWAY . . . I'm cheap and I admit it openly.
>
> Since batteries are a major consideration of total cost, my initial idea is
> to buy a 70-100 pound thrust trolling motor and match it to a Kipawa
> propeller, which will allow me considerably more money for batteries. I
> will use this system for this year and re-evaluate motor power next year.
> The batteries will already be paid for and my only need(battery-
> be whether or not I want to increase my range or to increase the power to
> accomodate a larger motor.
>
> I'm ridding myself of a 2005 9.9 HP Suzuki that runs okay, but too fast for
> my liking(I like to come into dock real, real slow).
>
> Last year, I lent my 55 pount thrust motor to a guy with a Precision 23 and
> he felt it was very adequate as long as he wasn't in a hurry or facing a
> strong headwind. I feel this motor would've offered him more power with a
> Kipawa propeller.
>
> BTW, very few sailboaters will go out in heady winds of about 15-20 knots
> and I tend to find myself on other's "bigger", boats in heavier winds, while
> my boat sits in dock.
>
> I know that I'm going to be considered "underpowered" by many, so I hope
> that my in-the-dirt experience will serve a good purpose. Especially so,
> since it appears that many of the posters who want to go electric, want to
> go somewhat cheap and seem to be concerned, first about power, then about
> range. I'm really not concerned about either, as long as I no longer have
> to handle gasoline or suffer the embarassment(
> of the tell-tale slick on the water. I'm make sure my Boat USA is caught up
> and fully in force.
>
> I will try to be somewhat conservative explaining my "system", and whether I
> will wind up considering it adequate or not.
>
>
> John Francis
> Pearson 26
> Port Clinton, Ohio
>
>
> On Tue, Apr 27, 2010 at 1:11 PM, Eric <ewdysar@...
>
> > John,
> >
> > While I believe that you're on the right track, however, I think that your
> > guesstimates are somewhat optimistic, skewed towards AGM. I've posted real
> > numbers a couple of times, most recently in post #13890. The delivered
> > energy ratios between battery types are less than 2 to 1, often much less.
> >
> > The rated capacity versus usable has also been discussed in detail many
> > times on this board, you can read specific answers from other people by
> > searching through previous posts. Usually a change in battery type will
> > only yield an additional 10-20% DoD, which calculates to an increase in
> > usable capacity of less than 35%. For most of my calculations I use the
> > following usable percentages: Flooded = 60% DoD, AGM = 70%, LFP = 80%.
> > These numbers are conservative, but should keep the battery banks healthy
> > without decreasing their projected lifespans much.
> >
> > Fair winds,
> > Eric
> > Marina del Rey, CA
> >
> > --- In electricboats@
> > >
> > > I just throwing figures out as I pretty much understand them to be.
> > >
> > > I'm hoping someone who has real numbers will jump in...
> > >
> > > In all fairness, when you buy a flooded deep cell you get about 20-30
> > > percent usage before you begin to potentially damage the battery and I
> > think
> > > that on high load the flooded cell drops faster than an AGM battery.
> > >
> > > When you add the deeper discharge that an AGM battery allows, you've
> > > probably cut the cost of each amp into about a third or less.
> > >
> > > SO, I think that each 3 amps or so(usable power) from a flooded battery,
> > > will equal something like 10 amps from an AGM battery . . . maybe more .
> > . .
> > > maybe less.
> > >
> > > PLUS if you pull a lot of amps out of a flooded cell, the battery will, I
> > > think will actually discharge faster than the ampreage rate and from what
> > I
> > > understand the AGM discharge will be much less.
> > >
> > > Given if this is true, an AGM battery will give you much more usable
> > power
> > > for a little more than a flooded cell battery.
> > >
> > > So to speak a cheaper AGM battery(less amps) might actually out-perform a
> > > more costly flooded cell with much higher amps. AFTER all, it's only the
> > > amps you can really make use of that mean anything.
> > >
> > >
> > > John Francis
> > > Pearson 26
> > > Port Clinton
> > >
> >
> >
> >
> >
> > ------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>
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