[Rhodes22-list] Solar Panels

[budconnor at earthlink.net]

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
>> 
>> __________________________________________________
>> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>
>__________________________________________________
>Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list