[Rhodes22-list] Solar panel inquiry

Thu Jul 19 22:59:57 EDT 2012

Charles,
Me again.  PBR.   Everything JJT said is true but I will stick to the
easy way of checking open circuit voltage to see if solar panel is
dead or alive.  Solar cells/panels can act like constant current
devices at a range of voltages and will produce very little power if
your battery is fully charged and the load is small.  So you would
need to check the amps in good sun with a significant load, like a
light or two on.  In this case you should get a good idea of the power
your panel is capable of producing...like he said.  Meanwhile, I
measured current on my boat - my instrument panel with 3 illuminated
rocker switches and powering my depth indicator and knot meter only
drew 0.2 amps.  So my previous assertion that a good charged battery
should handle that for days or weeks is reasonable.  However, with my
running lights in the mix, it took 2.0 amps, so this could easily kill
a perfect battery in a couple of days (say 80 amp-hour battery / 2
amps = 40 hours (with 100% efficiency, which never happens).  My bilge
pump takes 2.5 amps, I thought I would mention that since I checked
it.

So keep us posted.  If your battery has a shorted cell or is just done
for, that could be it.  If your panel(s) have been bad for a long time
that could be the problem.  Or, if you left any standard (non LED)
light bulb on, you might not have a problem at all.....except
forgetfulness.

If you reply, tell us how many panels you have and how physically
large which might help me guess the wattage.  My panel produces only 5
watts on a good sunny day so stands no chance of keeping up with a
single galley light bulb (12 watts=1 amp) or running lights.  But I
believe some Rhodes have 2 15 watt panels.  ( but those will cook your
battery prematurely if you don't have a charge controller - I don't
have any experience with that, my wisdom comes only from the list -
which seems to be very wise)

-PBR

On Mon, Jul 16, 2012 at 8:15 PM, Charles Nieman
<blue66corvette at hotmail.com> wrote:
> Where were you when I was fighting electrical engineering in college. This is the GREATEST explanation I have ever heard (and I have heard bunches). With this knowledge I could have been an electrical engineer instead of an architect ......... naw ....... Architect is better ......... HUGE AND MANY THANKS
>
> Charles
>
> On Jul 16, 2012, at 8:30 PM, jimtracyjohnston at centurytel.net wrote:
>
>> Charles,
>> In simple terms an electrical energy has two basic units, voltage and
>> amperage. Voltage is force or pressure on the electron to move in a
>> conductor, think of water pressure PSI. The amperage is the quanitiy of
>> electrons that are moving in a conductor. A squirt gun can have a great
>> deal of pressure (volts) as it squirts water, however, there is very
>> little volume or gallons per minute. The amperage is the quanity of
>> electrons that are moved i.e. gallons per minute. You need BOTH for a
>> useful electrical circuit. A test of your solor panel might indicate
>> the presence of voltage, however, if there is no amperage or quanity of
>> electrons being produced by the solor panel it can not refill your
>> battery. What would fill your bath tub first, a squirt gun with 100 PSI
>> (volts) and one pint/min. or a garden hose with 30 PSI max. but 5
>> gallon/min.? You can test a battery for voltage and get a reading,
>> however, it is "dead". Note the rating on batteries amp hours. You will
>> need to test for both voltage and amperage. Connect your solor panel to
>> any load (one wire to each end of a resistor) You measure the voltage
>> by putting a volt meter at each end of the resistor this is parallel.
>> Parellel means the electrons has a choice of going thru the resistor or
>> volt meter. Now to measure the amperage you must take one wire off the
>> load (resistor)  and put an ampmeter between the wire from the solor
>> panel and the load (resistor). This called in series and the electrons
>> have no choice, it must go thru the ampmeter and load to complete the
>> circuit. Even if there is voltage present the battery might not be
>> getting any electrons. Normally a power source will be rated watts.
>> This is the volts times the amps. Even if you have 12 volts but no amps
>> this means NO power. 12 volts times zero amps equals zero power. Good
>> Luck
>>
>> Quoting PBR <pbryanriley at gmail.com>:
>>> Charles,
>>> There are some previous posts about batteries, panels, and charge
>>> controllers.  A charged battery should be able to run your instrument
>>> panel only for days easily especially with solar panel(s).  So
>>> something is amiss.  Check your water levels.  Do you have a charge
>>> controller?  If not, that may have contributed to earlier battery
>>> degradation.  Four years is not bad, but with your light use I would
>>> expect them to last longer.  To test you solar panels you can check
>>> open circuit voltage with a voltmeter.  Disconnect the panels or
>>> disconnect you battery with everything else off.  In good sun your
>>> panels voltage shout produce an open circuit voltage significantly
>>> higher than battery voltage, say 15-20 volts.
>>> -PBR
>>>
>>>
>>> On Sat, Jul 14, 2012 at 1:48 PM, Charles Nieman
>>> <blue66corvette at hotmail.com> wrote:
>>>> So I left the instrument panel on when I left the boat a few days
>>> ago and came
>>> back to dead battery!! The penalty for being stupid.
>>>>
>>>> Hooked up a trickle charger to the battery and am now recharged.
>>>>
>>>> The question is, what is the best way to verify if my solar panels
>>> are still
>>> operational (I think they are original equipment and few things last
>>> forever)?
>>>>
>>>> And how much charge would one expect to get from fully operational solar
>>> chargers?
>>>>
>>>> The batteries are dated 2008, how many years could one expect these
>>> to last?
>>> (boat does not have electric motor hoist or electric start on outboard;
>>> batteries only power lights, AM/ FM radio, and compass/depth
>>> gauge/knot meter).
>>>>
>>>> Thanks in advance
>>>>
>>>> Charles Nieman
>>>> 98R22
>>>> DayDream
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>>
>>
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