It is currently Mon Sep 15, 2014 3:04 am

All times are UTC - 8 hours




Post new topic Reply to topic  [ 43 posts ]  Go to page Previous  1, 2
Author Message
 Post subject:
PostPosted: Fri Jun 08, 2007 4:44 pm 
Offline

Joined: Fri Jan 20, 2006 10:12 am
Posts: 545
Location: UK
Looks ok to me, but two potential improvements:

1) The panel's internal diode: I don't know what they normally come with, but if it's not a Schottky diode then you could improve effeciency slightly be replacing it with one.

2) A switching regulator between the panel and the battery would allow you to extract energy at lower light levels and also improve efficiency at high light levels. They do not have to be particularly complicated; you can probably find plenty of DIY designs out there.

_________________
https://mrevil.asvachin.eu/


Top
 Profile  
 
 Post subject:
PostPosted: Fri Jun 08, 2007 5:28 pm 
Offline
*Lifetime Patron*

Joined: Sat Jan 18, 2003 2:19 pm
Posts: 5316
Location: St Louis (county) Missouri USA
Well with this particular panel, the diode is completely internal. You can't even see it. I have no clue how you could tell what kind of diode it is, short of taking the thing apart.

As to the switching regular.....just what sort of improvement could I expect? Would it be worth the trouble/expense?

FWIW.....I found the perfect ac/dc small power supply for this setup(Harbor Freight). It's 18W, and contains a circuitry that prevents a battery from over-charging. If I ran this charger for eight hours at night, then let the solar panel run during the day, I could use the computer for about four hours every day......without discharging the battery. Of course these are paper calculations, and may not reflect real usage.......which remains to be seen.

_________________
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill disciplined, despotic, and useless. Liberalism is the philosophy of sniveling brats." - P.J. O'Rourke


Top
 Profile  
 
 Post subject:
PostPosted: Fri Jun 08, 2007 6:54 pm 
Offline

Joined: Fri Jan 20, 2006 10:12 am
Posts: 545
Location: UK
I thought this would be a pretty common DIY project, but I couldn't find much via Google. Maybe I'm searching for the wrong thing. Anyway, I did find one page with a variety of solar-related stuff, including a "Maximum Power Point Tracker" (no schematics though :() which is more complicated than what I was thinking of, but it says "MPPT can increase the power output of a PV system by about 20%".

Less complicated than that would be the simple regulator, specifically a buck/boost regulator, which is capable both of stepping up a low voltage and stepping down a high voltage to whatever the battery needs. You can get ICs that do all the complex stuff, needing only a handful of external components that could be assembled on stripboard. You can probably buy complete regulators specifically for charging batteries too, although that would undoubtedly be more expensive and less fun.

_________________
https://mrevil.asvachin.eu/


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jun 09, 2007 8:38 am 
Offline
*Lifetime Patron*

Joined: Sat Jan 18, 2003 2:19 pm
Posts: 5316
Location: St Louis (county) Missouri USA
Well since this is a cheap DIY project, that has yet to be tried out in a real usage setup, I'm going to try it before any more complicated add-ons. I got the little charger hooked up and working. It cost $16 from Harbor Freight. It was designed as a 1.5A trickle charger, and meant to be permanently attached to your car battery. Fits nice on the side of the battery box. How it will be used along with the solar charger.......I'll find out.

Image

Oh.....concerning possible over-charging of the battery. The solar panel only puts out 5W, but is unregulated, so it charges all the time when the sun is out. This small current will not overcharge a car battery....perfectly ok. A larger solar panel (Harbor Freight has a 45W model for $200), would need some sort of regulation, or it might overcharge. The little 1.5A ac charger in the photo does have a built-in regulation circuit, so it won't overcharge, even if left on all the time. I have to figure how much extra charge time is needed, because no doubt I'll be using this setup more than the solar panel can handle......

_________________
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill disciplined, despotic, and useless. Liberalism is the philosophy of sniveling brats." - P.J. O'Rourke


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jun 12, 2007 4:00 pm 
Offline

Joined: Sun Apr 29, 2007 1:20 am
Posts: 87
If you can do without the power of the P4, a mini-itx board will consume around 1/4th the amount of electricity.

If you need something more powerful, a Turion based system would work well. P4's are pretty energy inefficient.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jun 12, 2007 5:43 pm 
Offline
*Lifetime Patron*

Joined: Sat Jan 18, 2003 2:19 pm
Posts: 5316
Location: St Louis (county) Missouri USA
What you want to run off this sort of setup is completely your own choice. My other 12V computer uses the M-200 200W version of the PICO. It uses a P4-2.8 and could easily use this partial solar setup. A less powerful computer would draw less current from the battery.....and no doubt would give more run time off the battery, whatever 12v battery you would use.

On paper the solar panel by itself would pump maybe 50W back into the battery every day. My P4-2.4 uses about 50W per hour. That's how I arrived at the one hour run-time per day off the panel. Use a less powerful computer and you'll get more time per day off the panel. How this will work for me, remains to be seen. I still have some decisions to be made about where to set the battery.....and a few wires to run. But it is working on partial solar power....right now.

FWIW....the 12V battery system you see, is my back-up power supply when the AC goes down. (frequently around here) Hooked up to the solar panel should keep it fully charged all the time. Till now I just charged the battery every few months. The thing has helped me out of a number of power failures. In a pinch it could even start a car with a dead battery. :)

_________________
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill disciplined, despotic, and useless. Liberalism is the philosophy of sniveling brats." - P.J. O'Rourke


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jun 12, 2007 11:34 pm 
Offline

Joined: Thu Aug 17, 2006 7:14 am
Posts: 103
Location: Västerås, Sweden
Get your units straight, what do you mean by 50 W per hour? Do you mean it uses 50 W? 50 Wh per day? Watt is a power unit, Watt multiplied with time is energy. Watt (:)) do you mean?


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jun 13, 2007 2:18 am 
Offline
*Lifetime Patron*

Joined: Sat Jan 18, 2003 2:19 pm
Posts: 5316
Location: St Louis (county) Missouri USA
I suppose you want to see 50Wh.....something like that? My P4 actually registers a 46 on the Kill-A-Watt meter when running off AC. Off the battery it's something less, because the 12V ac/dc power supply is no longer in the system. The solar panel says 5W on the box.....that also means 5Wh. Sorry for the confusion.... :?

_________________
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill disciplined, despotic, and useless. Liberalism is the philosophy of sniveling brats." - P.J. O'Rourke


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jun 18, 2007 7:01 am 
Offline
*Lifetime Patron*

Joined: Sat Jan 18, 2003 2:19 pm
Posts: 5316
Location: St Louis (county) Missouri USA
Few more mods.....I'm now able to run a monitor (KDS Rad5) off the 12V battery, along with the computer. This was possible because this monitor uses a 12V wall wart to power the thing. I just found the proper connector (from Radio Shack) and spliced a longer harness directly to the battery. So now I have separate harnesses going to the battery. This monitor is rated at 3A (36W), so it adds quite a bit of draw to the system.

Overall, this system draws about 82W at an idle. I haven't checked battery life yet, and I may buy a new deep-discharge (marine) battery before I go much further.......

_________________
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill disciplined, despotic, and useless. Liberalism is the philosophy of sniveling brats." - P.J. O'Rourke


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jun 18, 2007 8:29 am 
Offline
*Lifetime Patron*

Joined: Fri Sep 26, 2003 6:28 pm
Posts: 408
Location: CT, USA
Bluefront wrote:
The solar panel says 5W on the box.....that also means 5Wh. Sorry for the confusion.... :?


i just have to be a pedant here... the box is correct. panels are always rated at the power they can generate. your panel puts out a max of 5W of POWER (probably under ideal, direct noon summer conditions). if you run it for an hour in perfect conditions, it has generated 5Wh (watt-hours) of ENERGY. similarly, your PC uses roughly 50W of power. running it for an hour requires 50 Wh of energy.

anyway, interesting project, though obviously not practical for frequent, extended use. but for what you want it seems to be good and it looks like fun to play around with. if you do end up buying a new battery, you may want to check out some DIY solar sites for battery recommendations. almost any battery will work in the short term, but you need to pick the right kind if you want good, long-term performance. lots of people use golf cart batteries. the best batteries are usually fork-lift ones, but they are wicked expensive.

_________________
main: athlon II 240e + Dark Knight, MSI 785GM-E65, Dell RM112, 4GB G-Skill, HVR-2250, 256GB Samsung 830 & 3TB WD Red, CM Elite 341
laptop: IBM Thinkpad X60s, LV CoreDuo 1.66, Samsung 840 120GB


Top
 Profile  
 
 Post subject:
PostPosted: Thu Jun 21, 2007 5:34 pm 
Offline
*Lifetime Patron*

Joined: Sat Jan 18, 2003 2:19 pm
Posts: 5316
Location: St Louis (county) Missouri USA
Well I haven't bought a new battery yet.....looking into it though. Problem is I don't want a battery so heavy I can barely carry it around. It's heavy enough right now, and it's a small battery. :lol:

I did locate a digital amp meter thats fairly accurate. I tested it against a known draw (an automotive headlamp) and it was right on. With the computer and the monitor running off the battery, the draw is 5A (60w)....less than what I figured. When I run CPUBurn, the draw jumps to 9A (108W). Not too bad.....I thought the monitor would draw more.

_________________
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill disciplined, despotic, and useless. Liberalism is the philosophy of sniveling brats." - P.J. O'Rourke


Top
 Profile  
 
 Post subject:
PostPosted: Fri Jun 22, 2007 7:26 am 
Offline

Joined: Thu May 31, 2007 1:58 am
Posts: 3
Suitable deep-discharge gel-based lead-acid batteries are usually sold as 'Solar' batteries. e.g. the Sonnenschein Dryfit solar. The 60 Ah version weighs 19 kg.
If that's too heavy you might have to resort to NiMh batteries, which weigh around 60 Wh/kg or Li-ion batteries at over 100 Wh/kg, but that would be more expensive than just buying a notebook computer and charge it using your solar panel.


Top
 Profile  
 
 Post subject:
PostPosted: Sat Jun 23, 2007 2:46 pm 
Offline
*Lifetime Patron*

Joined: Sat Jan 18, 2003 2:19 pm
Posts: 5316
Location: St Louis (county) Missouri USA
Well from a cost view-point, and being the practical person I am, I just might buy a marine battery that also fits in my car. I can get one for about $60. I could buy three of these for the price of some of those fancier batteries with a "solar" label on them.

I did manage to upgrade the video. I found an Insigina 15" LCD/TV at Best Buy. It works off 12V, and uses the same size plug as the PICO. Nice setup.....comes with an HD tuner, and multiple inputs including a VGA. Also has speakers, a remote, and a nice stand. It seems to draw about 20W....and runs ok off the battery. When the AC goes down, this will work much better than the little battery TV I was using....

If you go to the link and read the specs.....there is absolutely no mention of the 12V input, the possibility of running off a solar panel, or of how much current it draws. We've got a long way to go if this "green" thing is ever going to mean anything.

_________________
"At the core of liberalism is the spoiled child - miserable, as all spoiled children are, unsatisfied, demanding, ill disciplined, despotic, and useless. Liberalism is the philosophy of sniveling brats." - P.J. O'Rourke


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 43 posts ]  Go to page Previous  1, 2

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group