[Rhodes22-list] Solar Panels

[Slim]

Bud,

On a typical night sail, the nav lights are on for 3-5 hours and occasional
use of cabin lights.  We mostly use candles for light when at anchor and we
use a kerosene lantern for the anchor light.  We might go out at night once
in a week or up to three times a week.

Listening to myself, this is sounding like pretty minimal need.

Slim

On 6/13/06 6:46 AM, "budconnor at earthlink.net" <budconnor at earthlink.net>
wrote:

> Slim,
> the next question is ... how many hours per week do you leave each device
> turned on.
> Though it is beginning to look like your solar charging needs are going to be
> minimal.
> 
> -Bud
> 
> -----Original Message-----
>> From: Slim <salm at mn.rr.com>
>> Sent: Jun 13, 2006 4:28 AM
>> To: Rhodes22-list <rhodes22-list at rhodes22.org>
>> Subject: Re: [Rhodes22-list] Solar Panels
>> 
>> Dave,
>> 
>> Thanks a million for the basic overview.  That's just what I was looking
>> for.  With that explanation, now I can run my tests and at least do some
>> diagnosis.  
>> 
>> I do not have a generator on the outboard nor do I have electric start or a
>> stereo system.  The batts just run the lights, the VHF radio and the
>> cigarette lighter to charge the cell phones.
>> 
>> Slim
>> 
>> On 6/13/06 12:13 AM, "DCLewis1 at aol.com" <DCLewis1 at aol.com> wrote:
>> 
>>> 
>>> Slim, 
>>> 
>>> A little knowledge is a dangerous thing, and I¹m proof of that.   I¹m
>>> confident the guys on the board will have a good answer for you, but until
>>> they 
>>> respond let me take a wild crack at some of your questions.
>>> 
>>> If your boat is like mine, it¹s plumbed for 12 volts DC. You¹ve got 2  batts
>>> aboard. The main power switch adjacent to the V-berth lets you chose which
>>> battery to use to power your boat, or you can set the switch to BOTH and
>>> they
>>> will both power the boat together. If the batts were in series your
>>> electrical
>>> systems would be running of 12 volts when only 1 batt was being used, but 24
>>> volts when they both were being used - not likely.  Conclusion: when run
>>> together your batts are in parallel.
>>> 
>>> Your solar panels are supposed to trickle charge your batts. One may go  to
>>> one batt, the other to the other, so that when your main power switch is OFF
>>> each batt still gets a trickle. You can check this out on a sunny day.
>>> Disconnect the leads to your batts and using a voltmeter measure the voltage
>>> across 
>>> the loose disconnected leads, you should measure 12 volts, coming down  from
>>> the solar panels. Cover one panel, if the voltage goes away on one set of
>>> loose terminal leads, that¹s the panel that¹s supporting that batt, but also
>>> check the terminals from the other batt. If you cover one solar cell and
>>> both
>>> batts still show 12 volts (or if the voltage disappears on both sets of
>>> leads)
>>> they are wired in parallel from the solar panel¹s perspective. I haven¹t
>>> done
>>> this, but it should work.
>>> 
>>> Bigger (area) solar panels generally mean more power, or amps, but the
>>> output voltage is fixed. Generally, in my experience, they are sized for 12
>>> volts, 
>>> because they are usually used to trickle charge a lead acid auto batt.  But
>>> you should probably check, because the minute you don¹t you will find that
>>> what you¹ve bought is designed for some other voltage.
>>> 
>>> If the panel is designed to work with a lead acid auto batt, it¹s  output
>>> voltage is about 12 volts. The other 2 characteristics are power (watts)
>>> and
>>> current (amps). This is DC (Direct Current), so Power = Volts x Amps, you¹ve
>>> set 
>>> the volts, if you set the power you¹ve automatically set the amps and vice
>>> versa.  So if you know the Watts you know the Amps and vice versa, if you
>>> know 
>>> the design working voltage (12V).
>>> 
>>> How big a panel is ³enough²?  Solar panels are generally  trickle chargers,
>>> not prime power sources. Your batts handle the big surges -  and they also
>>> carry all the load at night. If you¹ve got a generator on your OB,  you may
>>> not 
>>> even need the panels, unless you go a long time without running your  OB. If
>>> you don¹t have a generator, you may need the trickle charge the solar  panel
>>> provides. How big a trickle charge? You can assess your typical usage and
>>> the
>>> size of batts and come up with an estimate, that should then be rounded up
>>> significantly, but for your purposes a good start might be the realization
>>> that  
>>> what you had worked, and the holes are pre-drilled, i.e. you might consider
>>> getting what you had because it worked.
>>> 
>>> If you want to ignore the pre-drilled aspect of your project and get a  new
>>> and different solar panel, you might measure the area of the panel and get a
>>> panel that is about that size. We all work with the same sun, the same
>>> silicon
>>> solar cells (approximately), and the systems are designed to work into 12
>>> volts  (be sure that's the case). Getting the same area solar panel should
>>> give 
>>> you  roughly the same current generating capacity as your old solar panel -
>>> within  bounds - unless the cells are markedly more or less efficient.
>>> 
>>> Or you might consider scaling down and not replacing the panel.
>>> Particularly
>>> if you've got a generator on your OB, that might suffice to charge  your
>>> batts.  I assume (but don't know) that a lot of the people on the  board do
>>> very 
>>> well with 1 panel.  Your usage profile may not be much  different than
>>> theirs.
>>> 
>>> I don¹t know if this helps.
>>> 
>>> Dave
>>> 
>>> __________________________________________________
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>> 
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> 
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