Solar Panels

[diceyface]

you're probably very sick of people asking for clear cases by now but i would really like one (for a reason)
i intend to mod it to have solar panels much like this project:
http://www.instructables.com/id/Solar-DS-quotLightquot-Redone-and-Greatly-Impr/
if i could purchase a clear case then i could mount the solar panels within the case (maybe with some hollowing out to do or something) and il never have to recharge the battery from the wall
although i could cut holes in the top of an existing case in order to have the panel sit flush with the surface...
tell me if i should make a separate thread on this or if it's a stupid idea
sorry to thread hijack

 

[Vorporeal]

Re: Pandora Case: final prototype

Mounting the panels inside would be a bad idea. The case would be translucent, but not transparent. You'd probably lose a good deal of charging efficiency/power by mounting them on the inside rather than the outside. Also, there's NO room inside the case for modding. You might be able to throw in a small microchip/PCB, maybe a small flash drive PCB if you're lucky, but there's absolutely no way you'd be able to put solar panels inside unless you hollowed out the top of the case a lot.

 

[lulzfish]

Re: Pandora Case: final prototype

Okay, it's like this:

To get enough power for the Pandora, you're going need WAY bigger panels than will fit on the Pandora.
Plus all the wiring, not to mention that it's either going to be in your pocket or you're going to be using it, covering any possible panels with your hands.

Solar is not practical for mobile stuff at all.

 

[Pleng]

Re: Pandora Case: final prototype

if i could purchase a clear case then i could mount the solar panels within the case (maybe with some hollowing out to do or something) and il never have to recharge the battery from the wall

I highly doubt that you'll be able to find solar panels that will give anywhere near enough power to mean that you'll never need to charge your Pandora from an external source again.

 

[WizardStan]

Re: Pandora Case: final prototype

Not to mention that solar panels can get HOT. The cheap ones are at best 20% efficient (give or take), which means the remaining 80% of the energy is converted to heat. The fact that the OMAP is a cool running processor means jack when you're injecting external heat into the system

 

[diceyface]

Re: Pandora Case: final prototype

The case would be translucent, but not transparent.

that's a very precise assumption

To get enough power for the Pandora, you're going need WAY bigger panels than will fit on the Pandora.

i just intended to trickle charge it (if you don't know what that mean then look it up)
it seems nobody followed the link i provided

Not to mention that solar panels can get HOT. The cheap ones are at best 20% efficient (give or take), which means the remaining 80% of the energy is converted to heat. The fact that the OMAP is a cool running processor means jack when you're injecting external heat into the system

this one really confused me, heating things up doesn't make them less efficient (unless combustion is involved but that's not really relevant)
i dont know where you live but here in England it's never sunny enough to do any form of damage and a solar panel wouldn't get any hotter than a normal matte black object in the sun let alone generate it's own heat like you seem to suggest

 

[JayFoxRox]

Re: Pandora Case: final prototype

I had to work out something about solar panels in school and I can say that you really need bigger panels.
Unless you buy some extremly expensive, super awesome solar panels you have no way of trickle charging your Pandora neither.
And if the tempature of the panels is too high they are about 90% less effective Iirc.
Besides that, like most people mentioned, your solar panels would be in a shadowed region most of the time. They would still charge your battery a slight bit but its again, by far not enough.

 

[WizardStan]

Re: Pandora Case: final prototype

Not to mention that solar panels can get HOT. The cheap ones are at best 20% efficient (give or take), which means the remaining 80% of the energy is converted to heat. The fact that the OMAP is a cool running processor means jack when you're injecting external heat into the system

this one really confused me, heating things up doesn't make them less efficient (unless combustion is involved but that's not really relevant)
i dont know where you live but here in England it's never sunny enough to do any form of damage and a solar panel wouldn't get any hotter than a normal matte black object in the sun let alone generate it's own heat like you seem to suggest

I didn't say it generated heat. The sun beams down (we'll say) 10 watts of power onto your solar panel. A 20% efficient solar panel converts 2 watts into electricity. The remaining 8 watts still exists, and is dissipated in the form of heat*. The heat has come from the inefficiency of the solar panel.
I don't know if I pity you or not, with your overcast English weather. On a typical summer day here in Southern Ontario, matte black objects become hot enough to burn (or at least be really, really uncomfortable to handle) within minutes of being left in the sun. I have seen black plastic warp after it was left in the sun for a few hours. I suppose I should have included a little bit more broad of a statement "any (especially dark) object left in the sun get very very hot", and encouraging that they be left in the sun by adding a solar panel sounds like asking for trouble.
My Pandora is going to stay in the shade, thank you very much.


* technically some of the light is also reflected, but whether it's 6, 7, or 8 watts out of 10, it's still a lot of wasted energy that becomes heat.

 

[Nation.A.List]

Re: Pandora Case: final prototype

I'm sure somebody sarcasticly remarked somewhere, that the Pandora could also make toast. Well now we all now how. :wacko:

 

[riumplus]

Re: Pandora Case: final prototype

I'm planning to use my Pandora with my Powermonkey eXplorer (https://powertraveller.com/iwantsome/primatepower/powermonkey-explorer/) when I'm out camping or on holiday. Its solar panel isn't that much larger than my PSP when unfolded. From past experience this has been more than enough to keep my phone, GPS, DS and PSP all charged with the amount I usually use them. It only needs to be left out in the sun every other day. I don't play them constantly though. But having an additional external battery I can use to recharge my devices is really handy. Never go anywhere without it sitting in the bottom of my bag, just in case.

Depending on how much you play it and how much sunlight the panel sees, something that size can be more than enough for the Pandora. But I don't even try charging it directly from the panel IMO; you'll need to trickle-store it in another battery designed to charge off that little current. Also means you don't have to sit in the sun all day long while it slowly charges, or leave your valuable Pandora outside.

 

[diceyface]

oh thankyou!
finally someone who doesn't want to tell me it's a stupid idea without really thinking about it
every little bit for the environment (hears everyone scoff and rolls eyes)
if i get the panels i intend to then i should get roughly 240 mA at 6.7V from the panels
all that's left is a little circuitry and a lot of case modding

 

[lulzfish]

So, 1.7 watts?
:/

Solar panels are flashy and all, but unless you're going to be outside all day with your Pandora, I'd just get a dynamo of some sort. You can use it indoors, produces more power, and conveniently fits in a cargo pocket when not being used. Probably. I don't know many dynamos.

Edit: If you're going to help the environment, I would suggest being more practical. Solar panels take a lot of investment and produce very little power unless they're mounted on your roof all day.

 

[WizardStan]

oh thankyou!finally someone who doesn't want to tell me it's a stupid idea without really thinking about it

We have thought about it. It is a stupid idea, for all the reasons explained.
Here's what you do instead: get a pair of 6 volt wheelchair batteries, and wire them to be charged from a solar charger mounted in a fixed position on your roof. For maximum efficiency, you then get a DC-DC transformer to take that 12 volts, ramp it down to 5, and current limit it to 1 amp. Solder on a USB connector and there you have it, a charging station for "free" energy.
For the devices that can't be charged via USB, you get an inverter to output 110 (220) volt and just use the standard charge plug. Not nearly as efficient, but it'd get the job done. What minimal excess there is can be fed back into the grid to offset your hydro bill. We'd be talking in pennies saved, but as you say, every little bit helps.
If done right, I imagine you could even make the solar charger portable enough (leaving the batteries behind) that you could take it on extended trips. Use a 6 foot cable, and you can keep your Pandora safely out of the sun as it charges.

 

[valhalla]

every little bit for the environment (hears everyone scoff and rolls eyes)

small panels that aren't left in the sun all day long are probably going to hurt the environment (for their production and disposement at their life end) more than they helped saving it with the energy produced.

I admit that they are convenient, expecially if you spend quite some time outside, away from electricity, but then an external panel with it's own battery is just more practical.

 

[Dauric]

I gotta agree that a larger portable solar "Recharging Station", or one of those gizmos that turns the kinetic energy of your walking pace to electricity, is your best bet here. Read the comments on that thread you linked to, the guy that posted that "Instructable" says to wait -days- of charging to ensure a noticeable charge before troubleshooting. That's for a DS battery that doesn't have the capacity of the Pandora's, or the same power draw on it. On top of that he's in Texas, a sunny desert territory, and you're in England. 'Trickle Charge' or no, you're hitting the limits of "Diminishing Returns".

I'm all for being efficient, but there's a difference between being really effective and just being trendy.

 

[Kag]

http://www.dealextreme.com/details.dx/sku.11936
Why not try something like this, it provides 5v not sure about the amp rating (Going by normal USB i would guess 500mA)

But still works when you charge 3.7v cellphone batteries.
Pandora's Batteries are 3.7v so it should work.

 

[Polossatik]

I looked into this a while ago, see
http://www.gp32x.de/board/index.php?ac ... 62&t=45904

Might be of interest.

Once i got the Pandore i'll have a other look at "solar power"...

 

[DAP]

Re: Pandora Case: final prototype

Not to mention that solar panels can get HOT. The cheap ones are at best 20% efficient (give or take), which means the remaining 80% of the energy is converted to heat. The fact that the OMAP is a cool running processor means jack when you're injecting external heat into the system

this one really confused me, heating things up doesn't make them less efficient (unless combustion is involved but that's not really relevant)
i dont know where you live but here in England it's never sunny enough to do any form of damage and a solar panel wouldn't get any hotter than a normal matte black object in the sun let alone generate it's own heat like you seem to suggest

I didn't say it generated heat. The sun beams down (we'll say) 10 watts of power onto your solar panel. A 20% efficient solar panel converts 2 watts into electricity. The remaining 8 watts still exists, and is dissipated in the form of heat*. The heat has come from the inefficiency of the solar panel.
I don't know if I pity you or not, with your overcast English weather. On a typical summer day here in Southern Ontario, matte black objects become hot enough to burn (or at least be really, really uncomfortable to handle) within minutes of being left in the sun. I have seen black plastic warp after it was left in the sun for a few hours. I suppose I should have included a little bit more broad of a statement "any (especially dark) object left in the sun get very very hot", and encouraging that they be left in the sun by adding a solar panel sounds like asking for trouble.
My Pandora is going to stay in the shade, thank you very much.


* technically some of the light is also reflected, but whether it's 6, 7, or 8 watts out of 10, it's still a lot of wasted energy that becomes heat.

So, if you leave your pandora in the sun, 20% of the light that hits it gets converted to electricity if you have solar panels on it, and 80% gets converted into heat. If you don't have solar panels on it, 100% of the light that hits the pandora gets turned into heat.

Solar panels for the pandora are completely impractical, but excessive heat is a poor argument against them since they actually reduce the heat the Pandora would suffer in the sun. This of course assumes you don't leave the Pandora in the sun intentionally attempting to charge it (waste of time since the solar cells would not generate enough energy to do anything significant).

 

[WizardStan]

Re: Pandora Case: final prototype

So, if you leave your pandora in the sun, 20% of the light that hits it gets converted to electricity if you have solar panels on it, and 80% gets converted into heat. If you don't have solar panels on it, 100% of the light that hits the pandora gets turned into heat.

Solar panels for the pandora are completely impractical, but excessive heat is a poor argument against them since they actually reduce the heat the Pandora would suffer in the sun. This of course assumes you don't leave the Pandora in the sun intentionally attempting to charge it (waste of time since the solar cells would not generate enough energy to do anything significant).

Reread the argument, specifically the second last sentence which says "encouraging that they be left in the sun by adding a solar panel sounds like asking for trouble."
I may not have been as clear in the first point, but I felt my second point still holds quite true.

 

[Dauric]

Re: Pandora Case: final prototype

Solar panels for the pandora are completely impractical, but excessive heat is a poor argument against them since they actually reduce the heat the Pandora would suffer in the sun. This of course assumes you don't leave the Pandora in the sun intentionally attempting to charge it (waste of time since the solar cells would not generate enough energy to do anything significant).

Heat accumulation is a perfectly valid argument. With solar panels you would require direct sunlight to get a useful amount of charge. Without solar panels there's no reason to put a Pandora in direct sunlight, and every reason to avoid sun exposure in the first place.

I may not have been as clear in the first point, but I felt my second point still holds quite true.

Stan's math may be fuzzy, but the principle is sound (last I heard 20% efficiency was a generous number, but that was some time ago). On top of that the Pandora will have a black case, sun exposure to any non-panel surface (ie: the sides, and the edges of the top that are not covered by panels) will convert (nearly) 100% of light to heat as well as absorb environmental heat energy, only dissipating that energy once the Pandora has been brought in to shade again. So even once you've removed your Pandora from the sunlight you're still cooking it's innards until the black plastic dumps all that heat (or rather equalizes that energy with the ambient temperature), as well as the heat still contained in the electronics, in to the Pandora's surroundings.