[Rhodes22-list] Peukert's Equation

elle watermusic38 at yahoo.com
Sun Jan 28 18:06:11 EST 2007


B.,
If you can't clarify, obfuscate.

Go sail.

elle

--- Bill Effros <bill at effros.com> wrote:

> L.
> 
> (A small woman with a short fuse?)
> 
> Here is an explanation of Peukert's Equation that I
> have not simplified.
> 
> If the mathematical symbols do not come through, go
> to this site:
> 
> http://www.smartgauge.co.uk/peukert.html
> 
> Bill Effros
> 
> *A proper explanation of Peukert's Equation
> (Peukert's Law)*
> 
> Mr Peukert first devised a formula that showed
> numerically how 
> discharging at higher rates actually removes more
> power from the battery 
> than a simple calculation would show it to do. For
> instance discharging 
> at 10 amps does not remove twice as much power as
> discharging at 5 amps. 
> It removes slightly more. Therefore a 100 amp hour
> battery (at the 20hr 
> rating) could provide 5 amps for 20 hours, but it
> could not provide 10 
> amps for 10 hours. The available time would actually
> be slightly less.
> 
> Mr Peukert wrote down a formula for describing how
> much less time would 
> be available. Please note that in the first
> paragraph I say "Mr Peukert 
> first devised a formula for....". This is because he
> is generally 
> regarded as being the man who first discovered the
> phenomenon. This is 
> incorrect. The effect had been known for many years
> beforehand and was 
> first noted by a certain Mr Schroder several years
> before Peukert 
> devised his formula. Mr Peukert simply quantified it
> in a way that had 
> never been done before. However the effect is now
> known as Peukert's 
> effect, the formula for calculating it is known as
> Peukert's equation, 
> and the important number, unique to each battery
> type, that is put into 
> the equation in order to perform the calculation, is
> known as Peukert's 
> exponent. Note that Peukert's exponent changes as
> the battery ages.
> 
> Please note that there are two ways of looking at
> this effect. We could 
> say that discharging at higher currents reduces the
> total available 
> power that can be got out of a battery. So a 100 amp
> hour battery might 
> become say an 80 amp hour battery at higher
> discharge rates. This is 
> technically the correct way of looking at it.
> 
> However it is easier to assume that the total
> available power in the 
> battery remains identical whatever the discharge
> rate. But that 
> discharging at higher rates removes more amp hours.
> This is the method 
> of explanation used throughout this website and on
> the Peukert 
> calculator spreadsheet.
> 
> Note that whichever method is used, the figures and
> effect remain 
> identical in both cases. It's just that we consider
> the second method to 
> be easier to understand and "get your head round".
> 
> Peukert's equation can be found all over place. On
> the internet, in 
> battery data sheets and documents, in battery sales
> literature, in 
> battery monitoring equipment manuals etc. It is
> usually written as I^n T 
> = C
> 
> Where:
> 
> I = the discharge current in amps
> T = the time in hours
> C = the capacity of the battery in amp hours
> n = Peukert's exponent for that particular battery
> type
> 
> The idea is that the time (T) that a certain battery
> can run a certain 
> load for can be calculated by rearranging the
> equation to read T = C/I^n
> 
> Please note that this equation, seen all over the
> place, is wrong. 
> Actually, I'd better rephrase that. The equation is
> not wrong. But the 
> way people attempt to apply it to the battery
> capacity is wrong.
> 
> This equation cannot be used on batteries that are
> specified at (say) 
> the 20 hour rate, or the 10 hour rate or any other
> "hour" rate. It will 
> not work. For an explanation of why and what
> equation you need to use 
> read the rest of this article.
> 
> Alternatively go here
> <http://www.smartgauge.co.uk/peukert3.html> to 
> find a suitable solution without understanding why.
> 
> Even a cursory attempt at using it will show that it
> simply cannot be 
> correct.
> 
> So let's try using this equation and see what we
> get.
> 
> The first problem we come across is that the battery
> capacity does not 
> state any type of rating. Is this the 100 hour rate?
> the 50 hour rate, 
> the 20 hour rate? or some other rate?
> 
> Most people assume it to be the 20 hour rate so we
> shall do the same here.
> 
> Take a battery rated as being 100 Ahr (at the 20
> hour rate - the most 
> usual specification) with a Peukert's exponent of
> 1.3 (a typical figure 
> for a deep cycle wet cell).
> 
> The rating on this battery means it can provide 100
> amp hours in total 
> at the 20 hour discharge rate. That is what the
> rating means. This 
> battery, when new, can provide 5 amps for 20 hours.
> 
> However, if we plug these numbers into the usual
> Peukert's equation (the 
> one that we see all over the place) we get:-
> 
> T = C/I^n
> T = 100/5^1.3
> T = 100/8.1
> T = 12.3 hours - yet we *know*, from the
> specification, that it can 
> provide this current for 20 hours!
> 
> Just plugging the battery's actual known capacity
> onto the equation 
> gives us the wrong result.
> 
> Ok, let's do a quick check on this. Let's do exactly
> the same 
> calculation but this time we will use 2 of the same
> battery i.e. 200 amp 
> hours, and the load will be exactly twice as much
> i.e. 10 amps instead 
> of 5 amps. Common sense (and experience and
> calculations) tells us that 
> the run time will be exactly the same as a single
> battery at 5 amps load.
> 
> T = C/I^n
> T = 200/10^1.3
> T = 200/19.9
> T = 10.0 hours - But we all *know* that it should be
> the same as the 
> above example
> 
> Let's just double check on this to make sure we
> haven't missed something.
> 
> The first result above suggests that this battery
> can actually only 
> provide 5 amps for 12.3 hours. That makes it a 5 X
> 12.3 amp hour battery 
> at this discharge rate. That means this equation
> tells us it can provide 
> a total of 61.5 amp hours when discharged at 5 amps.
> 
> So let's plug these new numbers into the equation
> and see where it gets 
> us:-
> 
> T = C/I^n
> T = 61.5/5^1.3
> T = 61.5/8.1
> T = 7.6 hours - So it has now decided something
> completely different.
> 
> Everytime we try to use this equation it makes the
> battery smaller!
> 
> Clearly there is something very wrong with the
> equation.
> 
> Well there is, and there isn't. There is nothing
> wrong with Peukert's 
> equation. It's simply that this is not how it should
> be used. Peukert's 
> equation shows the relationship between varying
> discharge rates. It 
> shows how the run time will be affected by changes
> in the discharge 
> current. It shows how they affect the battery run
> time and it's apparent 
> capacity. But it doesn't do this in relation to a
> specific battery 
> capacity. That is not how he intended it to be used.
> It was to be used 
> to calculate how increasing the charge current by,
> for instance, a 
> factor of 3 would affect the available run time. For
> instance assume a 
> discharge current of 10 amps gave them 40 hours run
> time from a certain 
> battery bank. This would mean that 10^n X 40 hours
> amp hours had been 
> consumed. This gave them their capacity at the 40
> hour rate. The above 
> equation could then be used to calculate the run
> time at say 20 amps. 
> Used that way it works quite well.
> 
> Whilst Peukert's equation is correct, it is not
> written in a way to 
> enable it to be simply applied to a certain battery
> in the way they are 
> usually rated. In order to do this we need to modify
> the equation so 
> that it takes into consideration the way the battery
> capacity is quoted. 
> The modified equation is:-
> 
> T = C/(I/(C/R))^n X (R/C)
> 
> Where:
> 
> I = the discharge current
> T = the time
> C = capacity of the battery
> n = Peukert's exponent for that particular battery
> type
> R = the battery hour rating, i.e. 100 hour rating,
> 20 hour rating, 10 
> hour rating etc.
> 
> What we have done here is modify the equation to
> operate effectively 
> given the battery capacity and hour rating.
> 
> This formula works. However, you must ensure that
> the correct hour 
> rating is inserted. If the battery capacity is
> quoted at a different 
> rate then this equation will give very misleading
> results. 99% of 
> batteries are rated at the 20 hour discharge rate.
> 
> If we now try the same experiment with the corrected
> version of the 
> equation:-
> 
> T = C/(I/(C/R))^n X (R/C)
> 
> We get:-
> 
> T = 100/(5/(100/20))^n X (20/100)
> T = 100/(5/5)^n X (0.2)
> T = 100/1 X (0.2)
> T = 100 X 0.2
> T = 20 hours, which we know to be correct.
> 
> We also know that doubling this discharge current
> should result in a bit 
> less than half the time available. We know that much
> to be certain, due 
> to Peukert's effect. Doubling the discharge current
> to 10 amps should 
> result in a bit less than 10 hours available run
> time.
> 
> So let's now try that calculation to convince us
> that our version of the 
> equation does indeed work correctly.
> 
> T = C/(I/(C/R))^n X (R/C)
> T = 100/(10/(100/20))^n X (20/100)
> T = 100/(10/5)^n X 0.2
> T = 100/(2)^n X 0.2
> T = 100/2.46 X 0.2
> T = 40.6 X 0.2 = 8.1 hours
> 
> Now that's more like it.
> 
> It is a mystery to us how magazine articles have
> been written using the 
> incorrect application of the equation. Also, the
> internet is full of 
> websites showing their author's expertise on all
> matter's Peukert, yet 
> quoting this incorrect usage of the equation.
> 
> The calculations are self contradictory when trying
> to use it and simply 
> do not work.
> 
> The only rational explanation we can think of is
> that people see the 
> formula, assume it to be correct, never actually try
> to use it, and 
> therefore never realise that it's actually wrong.
> This even seems to be 
> the case with magazine articles, battery monitor
> owners manuals and 
> several internet sites. It seems they haven't
> actually checked their 
> results against reality and just assume the
> calculated figures are 
> correct. But they do so enjoy showing their
> expertise and quoting the 
> equation, even though they clearly don't understand
> it. No other 
> explanation seems feasable.
> 
> One last point about the use of Peukert's equation.
> You may occasionally 
> see the equation written as T = Ca/I^n or in some
> other order but with 
> an extra figure in there somewhere (the "a" in this
> example). This extra 
> figure is usually specified as being an empirically
> derived factor, 
> usually with no explanation as to what it is for. We
> will call this 
> equation the fudged equation.
> 
> It is actually an attempt to modify the formula so
> that it works given a 
> certain battery capacity and hour rating. However
> the figure has to be 
> arrived at by trial and error by trying a
> calculation, and adjusting 
> this figure until the 20 hour calculation comes out
> correct. It's not 
> very elegant involving a lot of guesswork.
> Especially as the required 
> figure can actually be calculated from the given
> data!
> 
> The corrected version of the equation that we used
> above was kept in 
> that fashion because it is easy to work with for the
> examples above. 
> However, anyone with even a basic understanding of
> simple sums will 
> instantly spot that the equation can be rewritten
> either as T = 
> C(C/R)^n-1 /I^n or as T=R(C/R)^n /I^n (they are
> mathematically the 
> same). I consider this to be slightly more elegant
> but slightly more 
> complicated to work with for manual calculations.
> It's exactly the same 
> as the one worked through in the above examples but
> rearranged.
> 
> And those of you who are still awake will have
> spotted that the 
> (C/R)^n-1 the first of these two equations replaces
> the "a" in the 
> fudged equation. As I said, it seems odd to add an
> empirically derived 
> figure when it can be calculated from the given
> data.
> 
> Finally, you may also, on certain websites or in
> certain articles, see 
> it written as T = C/(Ia)^n . Where "a" is, again, an
> empirically derived 
> figure. This is a similar attempt to the fudged
> equation mentioned 
> above, and again, the empirically derived figure is
> guessed at until the 
> 20 hour calculation comes out correct. However in
> this case, the 
> emprically derived figure is in the wrong place in
> the equation and the 
> other results will be highly inaccurate.
> 
> Now, you've just seen how much less run time than 10
> hours is actually 
> available when a 100 amp hour battery is discharged
> at 10 amps. About 
> 17% less than a quick "amps X time" calculation
> would show. At higher 
> discharge rates the effect becomes very large
> indeed.
> 
> An often neglected aspect of Peukert's effect is
> that discharging at 
> lower rates will increase the run time quite
> substantially. For 
> instance, in our example of a 100 amp hour battery
> (at the 20 hour 
> rate), with a Peukert's exponent of 1.3, discharging
> the battery at 5 
> amps gives us 20 hours run time (so 100 amp hours
> are actually 
> available). Discharging at 2 amps gives us 66 hours
> run time. But wait, 
> that's 2 amps for 66 hours, that means the battery
> has provided 132 amp 
> hours. This is correct. At lower discharge rates,
> Peukert's effect means 
> the battery has a higher capacity. This is why it is
> so important to 
> check the rating on battery specifications. Rating
> this same battery at 
> the 100 hour discharge rate (instead of the more
> usual 20 hour rate) 
> would result in a higher amp hours "number" to stamp
> on the side of the 
> battery, thus making the battery *look* bigger than
> it really is. The 
> true capacity is exactly the same.
> 
> Discharging this same battery at 0.5 amps would give
> a total run time of 
> just under 400 hours. That means a total of 200 amp
> hours were provided 
> by the battery.
> 
> *Important note*
> 
> As described above, as the current approaches very
> low levels the total 
> available amp hours seems to increase beyond the
> capacity of the 
> battery. This is quite correct and the effect will
> be seen graphically 
> later in this article. However, balanced against
> this is the self 
> discharge of the battery which goes some way to
> cancelling this effect 
> at very low discharge currents. The final effect is
> that, at very low 
> discharge rates, the apparent total amp hours
> available from the battery 
> is never quite as high as a calculation based purely
> on Peukert's effect 
> would indicate. Some people incorrectly come to the
> conclusion that 
> Peukert's Equation does not operate correctly at
> very low discharge 
> rates. This is not the case. Peukert's Equation
> *does* work correctly at 
> *all* discharge rates. It just seems like it doesn't
> unless the battery 
> internal self drain is taken into consideration.
> 
> By way of example, Discharging the 100 amp hour
> battery at 0.5 amps (as 
> shown above) results in a run time of just under 400
> hours. That is 16 
> days and during that time a typical deep cycle wet
> cell battery could 
> well have self discharged by around 15 to 20 amp
> hours or so thus making 
> it *look* like Peukert's Equation did not operate
> correctly..
> 
> Now, whilst these figures are interesting, and quite
> illuminating to the 
> uninitiated, actually calculating them is incredibly
> boring. To sit 
> there with a calculator, running through the
> equation with different 
> figures is tedious to say the least. So........
> 
> Being the lovely people that we are.......
> 
> We have written you a simple Peukert calculator in
> Microsoft Excel 
> format and put it on this website. This will enable
> you to play to your 
> heart's desire. This calculator uses the exact same
> equation shown above 
> but rearranged to a more elegant format. You can
> download it by right 
> clicking here
> <http://www.smartgauge.co.uk/calcs/peukert.xls> and 
> selecting "save target as" or use the link on the
> left hand side.
> 
> This calculator will allow you to enter the battery
> capacity, the 
> capacity rating (i.e. 20 hour rating, 100 hour
> rating etc) and Peukert's 
> exponent for the battery type. It will then
> calculate a range of 
> discharge currents from very low up to a discharge
> equivalent to the 
> battery capacity. It then displays what is termed
> the "peukert corrected 
> amps" (which is the equivalent discharge rate such a
> load will remove 
> from that particular battery) for each discharge
> current and the 
> available run time, again for each discharge current
> (note that the time 
> is shown in hours as a decimal not in hours and
> minutes). Finally it 
> shows the total amp hours available from the battery
> at each discharge 
> rate.
> 
> There is also a window to allow the user to enter
> any discharge current 
> and it will calculate all the same values for that
> particular current.
> 
> Finally, there is a graph on the page which shows
> the discharge current 
> along the bottom, and the total available amp hours
> up the left hand side.
> 
> Typical Peukert exponents vary widely between
> different manufacturers 
> but an average figure for a true deep cycle battery
> is about 1.3. For 
> AGMs about 1.10 and for hybrids about 1.15. Have a
> play. You will be 
> surprised at just how much difference a heavy
> discharge rate makes to 
> the available run time. And perhaps also surprised
> at just how many amp 
> hours are available from a battery when the
> discharge rate is very low.
> 
> There is a much more detailed explanation of
> Peukert's Equation here 
> <http://www.smartgauge.co.uk/peukert_depth.html>
> along with a 
> mathematical explanation and proof of how any why
> our modifed equation 
> works correctly for a given battery capacity
> specification. This 
> equation is then developed further to produce one
> that will allow 
> Peukert's exponent to be calculated from a battery
> data sheet when this 
> information is not available. The maths is somewhat
> involved.
> 
> 
> 
> 
> Web site and all contents Copyright SmartGauge
> Electronics 2005, 2006, 
> 2007. All rights reserved.
> Page last updated 13/01/2007
> 
> 
> 
> elle wrote:
> > Bill,
> >
> > You are right, I have not used the R-22...but I am
> > familiar with solar panels & have had to calculate
> > drain on the  three other boats we have owned that
> > also had their own unique configurations of
> batteries,
> > chargers, toys, etc etc.
> >
> > I'm not interested in  !Quien es mas macho!...just
> > stick to the conversation & don't feel you have to
> > beat everyone down. We know you're smart...some
> others
> > on the list might be sorta smart, too....
> >
> > Why not publish your 'findings' as to each toy you
> > have aboard and its consumption. That's easy enugh
> to
> > do if you can read a meter. And it is not a
> function
> > of which type of battery you are currently using.
> >
> > Now THAT'S news we can use!
> >
> > BTW Bill..the name is elle. 
> >
> >
> >
> > BTW..Joe..after doing some research, it appears
> that
> > our hard solar panels may actually output more
> than
> > posted previously...the hard ones output more than
> the
> > flexible ones.
> >
> >
> > elle
> >
> >
> >
> >
> > --- Bill Effros <bill at effros.com> wrote:
> >
> >   
> >> L.
> >>
> >> I am not making those assumptions, you are 
> making
> >> those inferences.
> >>
> >> I have owned an R-22 for 10 years.  Every day I
> have
> >> been on board--well 
> >> over 500--I have noted the electrical
> consumption. 
> >> I have hooked up 
> >> single batteries and dual batteries.  I have used
> >> flooded, gel, and 
> >> AGM.  I have used motors with and without
> >> alternators.  I have used 
> >> solar panels, and I have covered them.  I know
> what
> >> I am talking about 
> >> from experience.
> >>
> >> You have not yet used your boat.  You are using
> >> tables and graphs that 
> >> are wrong for the boats for which they are
> >> written--and are even more 
> >> wrong for R-22s with Solar Panels.
> >>
> >> I have purchased additional Folding Solar Panels
> >> which I now use to 
> >> recharge all the appliance batteries on board.  I
> >> recharge all radios, 
> >> flashlights, cd players, etc -- including my VHF
> >> radio using solar 
> >> power.  I run a laptop off my batteries.  I run
> my
> >> cell phone off the 
> >> house batteries.
> >>
> >> My boat has never needed to be recharged from
> house
> >> current.  It is on a 
> >> mooring all summer and in a boatyard all winter. 
> I
> >> never remove the 
> >> batteries from the boat even though I live near
> NYC.
> >>  I could not do 
> >> that without the solar charger, since the motor
> does
> >> not run all 
> >> winter.  My boat batteries have never even come
> >> close to being fully 
> >> discharged.
> >>
> >> I accidentally shorted one of my batteries one
> year.
> >>  It did not short 
> >> out the other, even though the 2 batteries were
> >> connected in parallel.  
> >> When I realized what had happened, I disconnected
> >> the bad battery and 
> >> just used a single battery for the rest of the
> >> summer.  I never got 
> >> close to discharging the one, not as good as it
> used
> >> to be, battery.
> >>
> >> I am in the process of changing over all of my
> >> lights to LEDs.  I 
> >> suspect that I could leave the LEDs on 24/7 and
> that
> >> my batteries would 
> >> never run down with the solar cells on them.  But
> I
> >> haven't tested that 
> >> theory yet.
> >>
> >> Bill Effros
> >>
> >> elle wrote:
> >>     
> >>> Bill, 
> >>>
> >>> You are making two assumptions:
> >>> . that the R-22's have LED's rather than the
> >>>       
> >> installed
> >>     
> >>> incandescent lights; and 
> >>> 2) that the engine battery is 2a) the only
> >>>       
> >> battery,
> >>     
> >>> and 2b) that it is b=connected to the house
> >>>       
> >> lights.
> >>     
> >>> NOT!
> >>>
> >>> Each may be very different from what i
> described.
> >>>       
> >> I
> >>     
> >>> based my comments on my own configuration.
> >>>
> >>> Your mileage may vary.
> >>>
> >>> elle
> >>>
> >>>
> >>>
> >>> --- Bill Effros <bill at effros.com> wrote:
> >>>
> >>>   
> >>>       
> >>>> Hadz,
> >>>>
> >>>> Power consumption meters will do all the
> >>>> calculations for you.  While 
> >>>> they are expensive, they answer a lot of
> >>>>         
> >> questions,
> >>     
> >>>> and bring peace of 
> >>>> mind.  They will ultimately save you a lot of
> >>>>         
> >> money.
> >>     
> >>>> Solar panels actually do bring a lot to the
> >>>>         
> >> party. 
> >>     
> >>>> The consumption 
> >>>> figures L. and Art are using--which you will
> see
> >>>> widely used 
> >>>> elsewhere--are incorrect in real life.
> >>>>
> >>>> The starter motors on large boats draw far more
> >>>> electricity out of 
> >>>> batteries than an equivalent number of LEDs
> left
> >>>> burning for the same 
> >>>> calculated number of Amp-Hours.
> >>>>
> >>>> On our boats, motors with starters will put
> more
> >>>> electricity back into 
> >>>> the battery than they consume.  Solar cells are
> >>>>         
> >> all
> >>     
> >>>> that are required to 
> >>>> put electricity back into the batteries for
> >>>>         
> >> lights,
> >>     
> >>>> stereos,  and other 
> >>>> incidental uses.  When you are cruising you
> will
> >>>> inevitably wind up 
> >>>> using your motor a lot.  This will provide
> plenty
> >>>>         
> >> of
> >>     
> >>>> electricity for 
> >>>> auto-pilots and lights.  Should the battery
> fail,
> >>>> all you need to do is 
> >>>> pull the cord on our little motors to start
> >>>> them--you can't do that with 
> >>>> big boats which is why they factor in so much
> for
> >>>> idiots--the running 
> >>>> motor will provide the electricity you need for
> >>>> lights/autopilot/and 
> >>>> bringing the batteries back up to fully charged
> >>>> levels.
> >>>>
> >>>> One battery is all you really need on our boats
> >>>> almost all of the time.  
> >>>> 2 batteries are over-kill.  Top them off with
> >>>>         
> >> solar
> >>     
> >>>> panels most of the 
> >>>> time.  Get an electric starting motor.  Your
> >>>> batteries should never run 
> >>>> down if they are constantly topped off by solar
> >>>> panels.  Properly 
> >>>> maintained batteries that are never fully
> >>>>         
> >> discharged
> >>     
> >>>> will last for more 
> >>>> than 6 years.
> >>>>
> >>>> Bill Effros
> >>>>
> >>>> Joseph Hadzima wrote:
> >>>>     
> >>>>         
> >>>>> Thanks elle & Art!
> >>>>>
> >>>>> I had assumed the pannel utilitiy was related
> >>>>>           
> >> both
> >>     
> >>>>>       
> >>>>>           
> >>>> to
> >>>>     
> >>>>         
> >>>>> consumpson, and latitude; and since you're
> also
> >>>>>       
> >>>>>           
> >>>> just above
> >>>>     
> >>>>         
> >>>>> the 37th latitude, I appreciate your
> >>>>>           
> >> calculations.
> >>     
> >>>>>       
> >>>>>           
> >>>>  
> >>>>     
> >>>>         
> >>>>> --- "Arthur H. Czerwonky"
> >>>>>       
> >>>>>           
> >>>> <czerwonky at earthlink.net> wrote:
> >>>>     
> >>>>         
> >>>>>   
> >>>>>       
> >>>>>           
> >>>>>> Elle,
> >>>>>>
> >>>>>> Excellent perspective on the panels.  They
> >>>>>>             
> >> don't
> >>     
> >>>>>>         
> >>>>>>             
> >>>> bring
> >>>>     
> >>>>         
> >>>>>> much to the party.  I bought one of the LED
> >>>>>>         
> >>>>>>             
> >>>> utility
> >>>>     
> >>>>         
> >>>>>> lights from Boaters World at the Annapolis -
> >>>>>>             
> >> not
> >>     
> >>>>>>         
> >>>>>>             
> >>>> bad at
> >>>>     
> >>>>         
> >>>>>> all, and low power consumption.  I bought LED
> >>>>>>         
> >>>>>>             
> >>>> Xmas lights
> >>>>     
> >>>>         
> >>>>>> before the holidays, for next year's boat
> >>>>>>             
> >> parade
> >>     
> >>>>>>         
> >>>>>>             
> >>>> in
> >>>>     
> >>>>         
> >>>>>> Savannah possibly.  Five strings powered thru
> a
> >>>>>>         
> >>>>>>             
> >>>> 70 watt
> >>>>     
> >>>>         
> >>>>>> inverter (the lights were a/c because the DC
> >>>>>>             
> >> were
> >>     
> >>>>>>         
> >>>>>>             
> >>>> sold
> >>>>     
> >>>>         
> >>>>>> out) were no problem at all, plenty for 80'
> of
> >>>>>>         
> >>>>>>             
> >>>> big LED
> >>>>     
> >>>>         
> >>>>>> bulbs.  The mfg will not comment on amp draw,
> >>>>>>             
> >> but
> >>     
> >>>>>>         
> >>>>>>             
> >>>> it must
> >>>>     
> >>>>         
> >>>>>> be minescule.
> >>>>>>
> >>>>>> I really think the stability questions about
> >>>>>>             
> >> the
> >>     
> >>>>>>         
> >>>>>>             
> >>>> Rhodes
> >>>>     
> >>>>         
> >>>>>> have been  overdone, therefore of concern to
> >>>>>>             
> >> you,
> >>     
> >>>>>>         
> >>>>>>             
> >>>> Hadz,
> >>>>     
> >>>>         
> >>>>>> and others.  Each of us skipper has our own
> >>>>>>         
> >>>>>>             
> >>>> comfort
> >>>>     
> >>>>         
> >>>>>> boundaries, and this remarkable craft has the
> >>>>>>         
> >>>>>>             
> >>>> ability to
> >>>>     
> >>>>         
> >>>>>> adjust accordingly.  If you find the boat
> >>>>>>         
> >>>>>>             
> >>>> sensitive to
> >>>>     
> >>>>         
> >>>>>> particular winds, it is so simple to trim
> >>>>>>             
> >> either
> >>     
> >>>>>>         
> >>>>>>             
> >>>> main or
> >>>>     
> >>>>         
> >>>>>> genny.  Bill likes to stay level on the water
> >>>>>>             
> >> in
> >>     
> >>>>>>         
> >>>>>>             
> >>>> the LI
> >>>>     
> >>>>         
> >>>>>> area, even with the ability to steer with
> >>>>>>             
> >> weight
> >>     
> >>>>>> distribution.  Match that...
> >>>>>>
> >>>>>> I really don't think there is a boat to
> compare
> >>>>>>         
> >>>>>>             
> >>>> with
> >>>>     
> >>>>         
> >>>>>> our's in any catagory except maybe
> competitive
> >>>>>>         
> >>>>>>             
> >>>> racing
> >>>>     
> >>>>         
> >>>>>> with IMF.  
> >>>>>>
> >>>>>> I can't wait to read your first postings
> after
> >>>>>>         
> >>>>>>             
> >>>> you
> >>>>     
> >>>>         
> >>>>>> receive yours.  We will hear the Oh's! and
> Ah's
> >>>>>>         
> >>>>>>             
> >>>> in
> >>>>     
> >>>>         
> >>>>>> Atlanta, at Hartwell, and at Edenton without
> >>>>>>         
> >>>>>>             
> >>>> fail!  I can
> >>>>     
> >>>>         
> >>>>>> bet you're ready to get underway.  If you are
> a
> >>>>>>         
> >>>>>>             
> >>>> little
> >>>>     
> >>>>         
> >>>>>> short to see the bow, nary a problem because
> >>>>>>             
> >> you
> >>     
> >>>>>>         
> >>>>>>             
> >>>> will
> >>>>     
> >>>>         
> >>>>>> just levitate.
> >>>>>>
> >>>>>> Many cheers,
> >>>>>> Art
> >>>>>>
> >>>>>> -----Original Message-----
> >>>>>>     
> >>>>>>         
> >>>>>>             
> >>>>>>> From: elle <watermusic38 at yahoo.com>
> >>>>>>> Sent: Jan 27, 2007 12:41 PM
> >>>>>>> To: The Rhodes 22 mail list
> >>>>>>>           
> >>>>>>>               
> >>>> <rhodes22-list at rhodes22.org>
> >>>>     
> >>>>         
> >>>>>>> Subject: Re: [Rhodes22-list] speaking of
> solar
> >>>>>>>           
> >>>>>>>               
> >>>> panels
> >>>>     
> >>>>         
> >>>>>>> Hadz,
> >>>>>>>   
> >>>>>>>  Whether the solar panels can keep the
> >>>>>>>               
> >> batteries
> >>     
> >>>>>>>       
> >>>>>>>           
> >>>>>>>               
> >>>>>> charged is a function of the no. of  amp
> hours
> >>>>>>         
> >>>>>>             
> >>>> used by
> >>>>     
> >>>>         
> >>>>>> the goodies below.
> >>>>>>     
> >>>>>>         
> >>>>>>             
> >>>>>>>   
> >>>>>>>  I don't have my estimated numbers with me
> >>>>>>>               
> >> (I'm
> >>     
> >>>>>>>           
> >>>>>>>               
> >>>> at the
> >>>>     
> >>>>         
> >>>>>>>       
> >>>>>>>           
> >>>>>>>               
> >>>>>> marina working...!) but, for example, if you
> >>>>>>             
> >> have
> >>     
> >>>>>>         
> >>>>>>             
> >>>> 5
> >>>>     
> >>>>         
> >>>>>> interior lights below and if each interior
> >>>>>>             
> >> light 
> >>     
> >>>>>>         
> >>>>>>             
> >>>> pulls
> >>>>     
> >>>>         
> >>>>>> 1.5 amps/hr , you are using 7.5 amps per hour
> >>>>>>         
> >>>>>>             
> >>>> using all
> >>>>     
> >>>>         
> >>>>>> lights. Or you could use 1 light for 7.5
> hours.
> >>>>>>         
> >>>>>>             
> >>>> The solar
> >>>>     
> >>>>         
> >>>>>> panels may provide approx. 1-2 amp hrs/day
> each
> >>>>>>         
> >>>>>>             
> >>>> in this
> >>>>     
> >>>>         
> >>>>>> latitude (maybe a bit more when the days are
> >>>>>>         
> >>>>>>             
> >>>> longer &
> >>>>     
> >>>>         
> >>>>>> fewer when the days become shorter)...so
> >>>>>>         
> >>>>>>             
> >>>> estimating
> >>>>     
> >>>>         
> >>>>>> usage, and the knowing the % you can draw
> your
> >>>>>>         
> >>>>>>             
> >>>> batteries
> >>>>     
> >>>>         
> >>>>>> down, I'd say don't count on the solar panels
> >>>>>>         
> >>>>>>             
> >>>> doing more
> >>>>     
> >>>>         
> >>>>>> than to top 'em off.
> >>>>>>     
> >>>>>>         
> >>>>>>             
> >>>>>>>   
> >>>>>>>  When I did some estimates the other day, I
> >>>>>>>           
> >>>>>>>               
> >>>> figured I
> >>>>     
> >>>>         
> >>>>>>>       
> >>>>>>>           
> >>>>>>>               
> >>>>>> could stay out 2-3 days (if sunny), bieng
> >>>>>>         
> >>>>>>             
> >>>> conservative in
> >>>>     
> >>>>         
> >>>>>> use, and have to go in to recharge from shore
> >>>>>>         
> >>>>>>             
> >>>> power on
> >>>>     
> >>>>         
> >>>>>> the 3rd day...more or less.
> >>>>>>     
> >>>>>>         
> >>>>>>             
> >>>>>>>   
> >>>>>>>  elle
> >>>>>>>   
> >>>>>>>  
> >>>>>>> Joseph Hadzima <josef508 at yahoo.com> wrote:
> >>>>>>>  
> >>>>>>> I was under the impression that solar panels
> >>>>>>>           
> >>>>>>>               
> >>>> worked best
> >>>>     
> >>>>         
> >>>>>>> when they are set 90 degrees to the Sun.
> With
> >>>>>>>           
> >>>>>>>               
> >>>> the panels
> >>>>     
> >>>>         
> >>>>>>> statically mounted on the Rhodes, are they
> >>>>>>>           
> >>>>>>>               
> >>>> sufficient at
> >>>>     
> >>>>         
> >>>>>>> keeping the batteries charged during a
> typical
> >>>>>>>           
> >>>>>>>               
> >>>> weekend
> >>>>     
> >>>>         
> >>>>>>> cruise, or are they more for: charging when
> >>>>>>>               
> >> you
> >>     
> >>>>>>>           
> >>>>>>>               
> >>>> leave
> >>>>     
> >>>>         
> >>>>>>>       
> >>>>>>>           
> >>>>>>>               
> >>>>>> your
> >>>>>>     
> >>>>>>         
> >>>>>>             
> >>>>>>> boat tied at a mooring / slip during the
> week
> >>>>>>>           
> >>>>>>>               
> >>>> and sail
> >>>>     
> >>>>         
> >>>>>>>       
> >>>>>>>           
> >>>>>>>               
> >>>>>> on
> >>>>>>     
> >>>>>>         
> >>>>>>             
> >>>>>>> the weekend?
> >>>>>>>
> >>>>>>> I assume the latitude where you sail may
> >>>>>>>               
> >> affect
> >>     
> >>>>>>>           
> >>>>>>>               
> >>>> the
> >>>>     
> >>>>         
> >>>>>>> efficiency.
> >>>>>>>
> >>>>>>>       
> >>>>>>>           
> >>>>>>>               
> >>>>> HADZ (a.k.a. joe)
> >>>>>
> >>>>> "That's what a ship is, you know. It's not
> just
> >>>>>           
> >> a
> >>     
> >>>>>       
> >>>>>           
> >>>> keel and hull and a deck and sails. That's what
> a
> >>>> ship needs. But what a ship is... is freedom." 
> >>>>     
> >>>>         
> >>>>> -- Captain Jack Sparrow
> >>>>>
> >>>>>           
> >>
> __________________________________________________
> >>     
> >>>>> Use Rhodes22-list at rhodes22.org, Help?
> >>>>>       
> >>>>>           
> >>>> www.rhodes22.org/list
> >>>>     
> >>>>         
> >>>>>   
> >>>>>       
> >>>>>           
> >>
> __________________________________________________
> >>     
> >>>> Use Rhodes22-list at rhodes22.org, Help?
> >>>> www.rhodes22.org/list
> >>>>
> >>>>     
> >>>>         
> >>>
> >>>  
> >>>
> >>>       
> >
>
____________________________________________________________________________________
> >   
> >>> The fish are biting. 
> >>> Get more visitors on your site using Yahoo!
> Search
> >>>       
> >> Marketing.
> >>     
> >
>
http://searchmarketing.yahoo.com/arp/sponsoredsearch_v2.php
> >   
> >>>
> __________________________________________________
> >>> Use Rhodes22-list at rhodes22.org, Help?
> >>>       
> >> www.rhodes22.org/list
> >>     
> >>>   
> >>>       
> >>
> __________________________________________________
> >> Use Rhodes22-list at rhodes22.org, Help?
> >> www.rhodes22.org/list
> >>
> >>     
> >
> >
> >
> >  
> >
>
____________________________________________________________________________________
> > Looking for earth-friendly autos? 
> > Browse Top Cars by "Green Rating" at Yahoo! Autos'
> Green Center.
> > http://autos.yahoo.com/green_center/
> > __________________________________________________
> > Use Rhodes22-list at rhodes22.org, Help?
> www.rhodes22.org/list
> >
> >   
> __________________________________________________
> Use Rhodes22-list at rhodes22.org, Help?
> www.rhodes22.org/list
> 



 
____________________________________________________________________________________
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in the Yahoo! Answers Food & Drink Q&A.
http://answers.yahoo.com/dir/?link=list&sid=396545367


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