[Elecraft] Solar Panels on sale !!

[Sandy W5TVW]

I'd watch the voltage on the gel cell batteries!  They can be "floated" at  13.4-13.6
volts continuously or 1.47 volts for about a day.  Much over this and the life goes
to hell.

What is the expected life of the amorphous solar cell arrays, anybody know?

73,
Sandy W5TVW
----- Original Message ----- 
From: "Daniel Reynolds" <aa0ni at yahoo.com>
To: <elecraft at mailman.qth.net>
Sent: Tuesday, May 25, 2004 5:30 PM
Subject: Re: [Elecraft] Solar Panels on sale !!


| --- "Dave G." <dmg at bossig.com> wrote:
| > FWIW,
| > Harbor Freight has a 5W 12V Solar Panel on sale for #39.99 !!
| >
| > Usual disclaimers applpy !! Just got a Flyer in the mail  :-\
|
| I just picked one of these panels (#41144) up on Saturday from a local Harbor
| Freight. The panel is an amorphous design. I originally saw it listed on their
| website for $35.
|
| These figures are not precise, but I remember in bright sunlight the following
| measurements I took Saturday afternoon (about local noon).
|
| Open Circuit Voltage ~ 20 V
| Short Circuit Current ~ 2 A
|
| These values seemed high compared to another report I found online. One report
| I've read online suggests it effectively produces 3-4 Watts. I'm going to run
| my own tests sometime this week to find out how well mine works. Today it is
| cloudy, so I can't run a more refined test with power resistors.
|
| I currently have it tied to a 7AH gel cell to charge during the day. It sits in
| the back window of my car with the gel cell in the shade. I have no charge
| controller, so I plan on checking the voltage each day to make sure I don't
| overcharge it too much.
|
| The panel is nearly identical in size (18x12) to the side profile of the silver
| colored aluminum tool cases folks have been buying from Lowes, Home Depot, etc.
| Harbor Freight has the same tool cases (not just silver, but also in black
| panel with silver frame). Because of the size of the panel, it won't fit inside
| the tool case. It might be mountable to the side (it seems to be covered on the
| front with glass to protect the panel - the back of the panel might be more
| susceptible to damage), but I think that would not be as useful as having a
| panel free to float around the picnic table pavilion on Field Day (or in my
| back window where my K2 case definately WON'T fit). Maybe someone will figure
| out a way to temporarily mount the panel to the case for travel.
|
| I was able to generate enough power from the panel on Sunday afternoon (around
| 4-5 o'clock, with some haze in the sky) to power the K2 on receive (around 250
| mA). When a cloud came over, the radio would die. When the sun returned, it
| came back on. The voltage floated around quite a bit, but didn't seem to get
| too high (not more than 15 V that I could read on the K2... probably because
| the K2 was gobbling up 250 mA out of the manufacturer's stated 350 mA). When
| the 7 AH battery was added to the circuit (KBT2 disengaged), the voltage
| stabilized considerably (around 12.2-12.3 - I think the 7AH battery was low).
|
| Only caveat I've read so far about amorphous solar panels is that they wear out
| faster than single crystal cells.
|
| For the initial layout ($40 + tax), I'm not going to complain. It seems to
| perfectly compliment my K2 and the 7AH gel cell I recently acquired for Field
| Day.
|
| 72,
| Daniel / AA0NI
| Oklahoma City
|
| _______________________________________________
| Elecraft mailing list
| Post to: Elecraft at mailman.qth.net
| http://mailman.qth.net/mailman/listinfo/elecraft
| You must be a subscriber to post.
| Elecraft web page: http://www.elecraft.com
|
|