[Rhodes22-list] Peukert's Equation
Bill Effros
bill at effros.com
Mon Jan 29 13:53:42 EST 2007
Mike,
The equation sort of works for all batteries.
I say "sort of" only because when you try to plug it in in real life
situations you can't find a constant.
But the underlying principle is so important to small boat owners who
lug around far more battery power than they will ever need because they
don't understand that amp/hours vary with draw, and that the devices we
use on our little boats have minuscule draw compared to the draw assumed
in the ratings provided by battery manufacturers.
I'm not an engineer, so, of course, I had never heard of either Peukert
or his law before getting my boat.
I got my gauge for piece of mind. For some reason, relying on "idiot
factors" doesn't work for me. I like to know where I stand. At first I
thought the gauge was wrong. But I never ran out of juice, and my
batteries held a higher charge than I thought was possible. So I got a
meter to confirm the readings on the gauge--and, Damn! if they weren't
exactly the same.
So I read the manual which explained about Peukert, and why everything I
had always thought I knew was wrong.
With regard to L., out of deference to Ed I don't speak French on this
list. Also, my father always insisted that I never refer to a woman as
"she".
Bill Effros
Michael D. Weisner wrote:
> Bill,
>
> Thank you for a great source of info!!! The SmartGauge technical articles
> are gems (at least the few that I was able to read while at work)! Can this
> info be applied across the board to all battery types? I thought that
> Peukert studied high capacity NiCd cells and yet we are talking about Pb
> cells. Are there different fudge factors for other chemistries?
>
> BTW, isn't "elle" short enough already? Must you insist on "L"? (Sorry,
> elle, I couldn't resist.)
>
> Mike
> s/v Shanghai'd Summer ('81)
>
> From: "Bill Effros" <bill at effros.com> Sunday, January 28, 2007 7:16 PM
>
>> 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
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
> ____________________________________________________________________________
> ________
>
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>>> 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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