With 2 full charged nicds, which in a simple charging circuit should be limited to about 1.35V, would be 2.7V. Most white LEDs need about 3.15V for about 18ma. Most need about 2.9V to glow much at all. It won't need a resistor. It will need one of Claude's boost circuits.
Say with 24 LEDs at 18ma... In a simple circuit (3.6V), 24 x 18 = 432ma. 4H run time is 1728ma. 1.5H insolation means 1152ma of panel. 3.6V + 0.7V + .3 for losses = 4.6V, meaning 10 cells though 8 may be OK. With 10 cells thats 6.7W.
In a 12V system it needs 144ma, x4 = 576mah, 1.5H insolation is 384ma of PV, 36 cells, 6.5W. Notice the wire can be a LOT smaller. And the system can have a diode loss, and still have 3V of additional losses.
The 12V system can use 2 VW PVs and have power to spare. ($30~50?)
The yard light toys make about 15ma Isc on the ones I played with. IF they made enough to charge 3 cells, it would take 116, but they don't, so it would take 232. At $3 each, it's either $348 or $696.
My wife isn't keen on "A" PV, I won't ask about 232 mini PVs.
AAs won't cut it here either. We can go 3 days and not get up to charging voltage.
This is an example of costs for an average person to have a fully functional system.
I have well into double digits of 5W class PVs, 5 figures of white LEDs, a dozen new SLAs, and "a lot" of AA and bigger nicds here. My cost would be a fraction to put up a real system. G-[ Parent ]
Leds work quite well with 2 nicad batteries, tell the makers of yard lights that their calculators all need new batteries and their leds need 2.9 volts instead of 2.7, see what they say.
About a square foot or less of pv and a few batteries should do the trick for a desk lamp, wholey moley.[ Parent ]
Mostly "he" is "me".
I (and he, and me) am talking about a real life replacement of a grid fed 5W rated CFL. It needs to come on when the switch is clicked. Good marketing and crappy products is why solar has a bad rep.
Some barely glowing yellow novelty ain't gonna cut it. I watch every night as the neighbors yellow LED yard lights click off with the sun setting (not a typo. They come on a little before sunset. Then go off around sunset), and I know white LEDs will not be as good.
Show me a white LED that works quite well on 2 nicds. Show me a white LED data sheet that shows a white LED with rated MCDs at 2.7V. Show me a boost regulator that is more reliable than a 1/4W resistor.
Headhunters call me about LED design jobs, but I will not relocate. Or work 9-5, if I don't want to on that day. But I decline. I have serious obligations here. And I almost like sorting resistors/TO-92s/TO-220s into tiny bags for someone excited about a new windmill in who-knows-what-corner-of-the-world.
Major brand names offer to put my name on their package. I get the stuff you talk about in skid quantities. The boxes have my name printed on every one.
I have stuff made to MY specs in China, Taiwan, Hong Kong, Korea, etc. I don't have them put a different sticker on some Wally-World crap.
Do you remember, long ago, when you were selling those re-stickered Chinese inverters just like the inverters at Wally-World, but probably seconds (without your knowledge)? Do you remember when someone asked about large quantities of 12V 175W and 400W inverters, but you said there wasn't a market or profit or something like that? Yup. That was me.
Anyway. If you have the data sheets for those $3 yard lights with 2 nicds, a PV, and some kind of white LED that runs directly from 2.7V, 10 hours full brightness with yard light quality AAs, and no regulator, please post a link.
G- (sorry TomW, Kurt, Woof, but you must have seen it comming) [ Parent ]
Anyhoo...
Taking this from another angle: when efforts are being made to put together solar lighting solutions for 3rd-world off-grid villages where the extra expense is far more than just an annoyance, how do/can they keep prices for the completed unit a little lower?
For example, how much of this could be integrated? Could the solar controller and CFL ballast be put on one board and share any parts?
Rgds
Damon[ Parent ]
With your knowledge why are you asking for help here again?
As far as the inverters are concerned, there is no market for a person like me to buy 175 watt inverters, pay the sea freight and try to sell them when you can buy them at walmart for next to nothing...I can't compete with that, nor would it make good business sense to try.
The inverters I was selling were top notch, brand new and unstickered in plain white boxes, I was trying to help this community and pass on the savings...with my knowledge of inverters and connections in China which are both very good.
Tell me where you can buy a 5000 watt inverter, with volt and amp meters and wireless remote for under 300.00? Don't get me started on dirt cheap magnets either.
Many people bought those inverters and magnets, do you see any posts about me selling junk or offering bad service? Attitudes like yours is what killed the project, I can get anything at any quantity out of China, I was just trying to help people on this board, there was no grand scheme in place to make large profits.[ Parent ]
You can surely buy all that separately for 25 dollars or more, sorry just my limited experience again...maybe its better to build a mill and put up a bank of 12 volt batts to run a led desk lamp...sorry I got involved and I apologize for any animals that have been harmed as a result of my stupidity. [ Parent ]
