Solar Charger I Found


HackModford

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What do you think? This would come in handy in the inevitable economic breakdown right?
 
"1000mAh Li-ion battery"
That is: it's internal battery is 1/4 of the Pandora's one.
That means you will get 12.5 hours instead of 10 (probably will end up being 11.5 instead of 9.5).
So:
-provided you have 8 hours of sun to charge completely the internal battery,
-provided you actually have a place where to put the charger,
you will probably get 2 (or less) "free energy" hours of pandora use per-day.

But you could actually glue it to the Pandora so this might become a nice idea :D
 
HackModford said:
What do you think? This would come in handy in the inevitable economic breakdown right?



In theory, yes. In practice, no.

Pretty much every review I've seen of that device says it might work if you're in the Sahara, but otherwise the light just isn't bright enough to get a decent charge.
 
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We did look in to putting a solar 'coat' on the Pandora... for about 20 minutes.

Essentially it would take about a week to get a decent charge and would thicken the unit out a lot more.

OK if you don't plan to use it much :)
 
Then your best bet is too just build your own right? I'm more interested in "charging" than running of a battery...
 
I've got something similar, when I take my phone on a long boat cruise or camping I charge it with something like this, used to do a mighty fine job of charging my PSP too.
 
HackModford said:
Then your best bet is too just build your own right? I'm more interested in "charging" than running of a battery...
It's nothing particularly specific to that device - basically solar panels are hideously inefficient - only a tiny fraction of the light energy that hits them gets turned into electricity. You could give a Pandora a good charge with the sort of large roof mountable panels that cost thousands, but any panel small enough to carry around (or just carry!) isn't going to produce enough current to charge at any sensible speed (as Craig said, a good week or so to get a decent charge)
 
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how well would this work in sunny ireland :(
dont bother replying i already know the answer
 
Based upon the photos, looks to be about 8 sq. inches of solar panel.
If its a real good panel, it will get approx. 12% efficiency in clear noon sunlight.

Clear noon sunlight is approx. 100 W/sq. ft.
8 in. sq. = 8/144 = 0.06 sq. ft.

100W X 0.12 X 0.06 = 0.7 W

If you have four hours of real good sunlight, and place it in it, you'll get:
0.7W X 4 hours = 2.1 Watt hours.

For a 1100mAh battery at 5.5V, you need:

1100mAh / 5.5V = 200 watts for one hour (or equivalent) to fully charge it.
In the real world, you'd use a Li ion charger for five or six hours at 50 watts load to charge it.
If you use usb, then at the 500mA normal USB limit, it would take 2.1 hours at balls to the wall
maximum usb load to fully charge a fully discharged 1100mAh battery.
Again, in reality, it would take four or five hours to top up a 70% discharged battery with usb.

At 2.1 Watt hours in one day, you'd need 100 days to fully charge the battery in this solar charger.

The product is bullshit.
You need more solar panel area to get enough energy to charge a battery like this.

If you want to fully charge an 1100mAh battery in one average day of real good sunlight, you'd need a panel 100 times bigger.
Or, 800 square inches, roughly Seven square feet.
Something like this:
http://www.siliconsolar.com/shop/solarimag...rger-15W_D5.jpg
 
j.pickens said:
Based upon the photos, looks to be about 8 sq. inches of solar panel.

...snip...

You need more solar panel area to get enough energy to charge a battery like this.
Thanks - I'm far too tired to work out the maths myself :)

All I can say is I've never been satisfied with any solar panel I've ever bought - small ones are only any use to powering things like pocket calculators that really don't need a huge amount of power in the first place!
 
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HackModford said:
What do you think? This would come in handy in the inevitable economic breakdown right?


Walmart sells a solar powered auto cooler that uses pretty good quality glass solar panel to turn a pretty strong fan and it's $17 and creates more power than this $50 thing. You can also pick up a trickle charger at pepboys for 69.99 that puts out about 17 watts in full sun. It's bigger but size matters. If you charge it up during the day, you can run it at night for free. Just use a cigarette lighter adapter and you can charge your pandora in a few hours. If you really look around and are willing to put some thought into it, you can find some good ideas.
Of course, if you are worried about an economic breakdown (which I am), the Pandora is going to be the least of your concerns.

Chris

j.pickens said:
Based upon the photos, looks to be about 8 sq. inches of solar panel.
If its a real good panel, it will get approx. 12% efficiency in clear noon sunlight.

Clear noon sunlight is approx. 100 W/sq. ft.
8 in. sq. = 8/144 = 0.06 sq. ft.

100W X 0.12 X 0.06 = 0.7 W

If you have four hours of real good sunlight, and place it in it, you'll get:
0.7W X 4 hours = 2.1 Watt hours.

For a 1100mAh battery at 5.5V, you need:

1100mAh / 5.5V = 200 watts for one hour (or equivalent) to fully charge it.
In the real world, you'd use a Li ion charger for five or six hours at 50 watts load to charge it.
If you use usb, then at the 500mA normal USB limit, it would take 2.1 hours at balls to the wall
maximum usb load to fully charge a fully discharged 1100mAh battery.
Again, in reality, it would take four or five hours to top up a 70% discharged battery with usb.

At 2.1 Watt hours in one day, you'd need 100 days to fully charge the battery in this solar charger.

The product is bullshit.
You need more solar panel area to get enough energy to charge a battery like this.

If you want to fully charge an 1100mAh battery in one average day of real good sunlight, you'd need a panel 100 times bigger.
Or, 800 square inches, roughly Seven square feet.
Something like this:
http://www.siliconsolar.com/shop/solarimag...rger-15W_D5.jpg


Your math is faulty. You do not need 200 watts to charge a 5.5v 1100mah battery. That is 6.05 watt hours. Given the inefficiency of batteries as they get closer and closer to 100% charged, you might need 10watt hours to charge it.

Chris

Butterman said:
j.pickens said:
If you want to fully charge an 1100mAh battery in one average day of real good sunlight, you'd need a panel 100 times bigger.
Or, 800 square inches, roughly Seven square feet.
Something like this:
http://www.siliconsolar.com/shop/solarimag...rger-15W_D5.jpg



Well, mine was about 1 sq ft when folded out, it was quite expensive too. :D

a 7 square ft solar panel should have NO PROBLEM charging a pandora battery. I've seen 50 watt solar panels about that size. Photovoltaics is not terribly efficient, but it's not that bad. Small solar panels ON MARS are creating 700+ watts in a fairly short Martial sol, receiving 1/2 the sunlight.

Chris
 
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Forget about solar. Use those kinetic mechanisms that are in watches. I would guess that if you put enough of those, you might have enough energy for minimal things.

I no, I no, too heavy too expensive, and probably not gonna work. But a man can dream can't he? :p
 
christo930 said:
Your math is faulty. You do not need 200 watts to charge a 5.5v 1100mah battery. That is 6.05 watt hours. Given the inefficiency of batteries as they get closer and closer to 100% charged, you might need 10watt hours to charge it.
Oops, the mA to A conversion screwed me up.
But even so, my Wh calculation was correct.
So, instead of 100 days to charge it up, it would be more like 5 days, using your 10 Wh value.
Still, a steaming pile of false hope in that solar battery "charger".
 
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5 days huh, seems craig's estimation that it would take a week to power the sucker, was pretty spot on. Which is like 1.5 hours of use each day on average.
 
I also looked into this a time ago in this thread.

Might have some usefull info.

Once my bank balance is back to normal (damn holliday's :) ) i'll order some panels ...
 
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I've been using the Solio: http://www.solio.com/charger/

It takes about 2 days of decent sun to charge. Once charged, it can charge up my iPod almost 2 full charges. So for the iPod, it's not bad at all.

I'm not getting any unrealistic expectations about it charging the pandora. I'll just have to wait until it arrives before I can experiment.
 
If you were to being living somewhere hot and could make do with one of these, I wouldn't want my pandora sat in roasting hot weather in direct sunlight.

Unless i was on a small boat, I can't imagine there is many people that can't get to a wall socket or USB port every couple of days. And given that we've got the best part of 10 hours (maybe more) battery life, i don't think it's a viable options.
 
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