Solar Charging in A Stormy/Cloudy Day ?

Back in 1996, we had that crazy El Nino storm that whipped thru here in Northern Calif. My mom, dad, brother and I live in the outskirts of town, when the power goes out, NO power for FOUR days. I went to Fortuna which is about 5 to 8 miles away from us. I bought at C.Crane Radio a solar charger which charges up Ni-Cad batteries and bought a CC Trek Light that has 2 LED lights that don't take much power. C.Crane does mail order, but i don't live too far from the place! ALL The stores ran out of batteries, But C.Crane told me to get a charger and if we get lucky, some sun may SHINE thru the clouds. Maybe a short break in the weather. We had a moment in the day time when the clouds weren't so DARK GRAY and i put the charger to the windows moving it around with the AA batteries inside. My dad told me to leave the AA's in all day so they'll get a full charge. That did the trick. When night time came around I turned the flashlight on. One has to twist the lens cap to turn it on. It wasn't bright, but just enough to see where one is going. My dad was amazed at how this solar charging these "AA"'s saved the day. After the storm was over I bought Alkaline batteries and noticed at nite time that the beam is much BRIGHTER than the Ni-Cad batteries.

If anyone ever had a similar experience like I had, please let's hear from you. Also, I posted info and got different responses from those who used "shake lights" ( with the magnets inside) and from what I read that some guys like Pydpiper and what Paulr posted, I'm not too sure if that's the type of light one wants to spend up to $40.00 of hard earn money on. Do the shake lights really have lithium batteries inside? I wrote to Applied Innovative Technology (AIT) and they said the lights have "capacitors" inside. I like to hear from others about how their so called emergency lights worked for them on a real emergency. Anyone ever had to used SOLAR power to charge batteries for a nite time or anytime emergency use?? Robt..

I'd like to believe that AIT has stuck to proper design and used capacitors. There are some shonky copycat manufacturers who used CR2032 cells to make it light, but naturally, it can't recharge.

The original inventors of the Nightstar Shakelight did use capacitors and their product, IMHO, is well worth the money you spend. Not very bright, but built like a brick dunny. Water tight, sealed magnetic switch, repelling magnets instead of rubber bumpers. A brighter solution is the new cranklights that look like a bullet train. You can select between 1 and 3 LEDs and they each run at full brightness, so it is heaps brighter than the shakelight. But it isn't built quite as tough for your SHTF emergencies, but still good enough to handle most situations.

If you're planning to use solar cells for recharging in overcast weather, I suggest building in a little booster circuit, or getting quite a few more solar cells and connecting them in series, possibly together with a voltage shunt or voltage regulator. I found a design some time ago for the booster circuit, which I'm happy to share. I just need to dig it out.

The basic premise for what I wrote above is this:
Solar cells have the following characteristics. Each photovoltaic junction produces 0.5V, but only if the minimum level of illumination is met. The greater the surface area, the higher the current. Once past the minimum level of illumination, any extra intensity results in higher output current.

To recharge a cell, you need a certain voltage. Approx. 1.5V for NiCd and NiMh cells. If you don't meet this, it doesn't matter how much current you have available, your cell is never going to charge. Of course you do need at least 10mA to recharge (to at least exceed the self-discharge rate of NiMh), but that is not as important as the voltage.

Most solar recharger manufacturers build to minimum requirements, partly to protect your cells from overcharging, but mostly to maximise profits. Minimum requirements means just enough voltage in full sun to meet charging requirements.

On an overcast day, you'd be lucky to get past the minimum level of illumination, which means you never get enough voltage to actually begin charging. To get past that point, you can either boost whatever power you have to reach the correct voltage, or string together enough cells in series so that you get the required voltage even under overcast skies. In both cases, more surface area means more power. In the second case, you have to protect yourself in case the sun comes out and the solar cells deliver full voltage and fry your cells.

Hello i'm new to the forums here and can't add much other than that I need a solar recharging system for an led lighting system for my kitchen at the carslisle car shows. As far as the nightstar shakelight goes as a long term use as an emergency light goes I have been using and selling them for several years they fill a specific niche and are not the most powerfull but are the best shake light I have used and that taking into consideration that most people do not check there alkaline or other rechargebale batt powered flashlights, Leading to repair issues I have changed to shake lights for all my emergency lights although I am a Flashaholic I do belive there is a light for every use and no one light can possibly fit all use's. thanks phil

Say SteelWolf, the guys at Applied Innovative Technology, are they the "original inventors"? If yes, do i purchase from them if i decide to get a shake light? I read messages at this candlepowerforum what others say. I wouldn't use a shake light to fix things around the home or for fixing my car, but it would be a life saver just for when we have a power outtage and i need to SEE where the heck i'm going so i don't fall over anything or to cook by. That's all it would use it for.. I wrote to AIT and asked if there's capacitors AND 2 lithium button cells and i didn't get any responses from them yet.

Robt I have several of the full size clear barrell shakelites on hand I know that the specs on the light call for it to have a capacitor there are no batteries in this unit. Just a capacitor if you would like the specs on this light just pm me with what you need. Yes ait is the oem to the best of my knowledge there only mistake seems to be they shipped production off-shore hence all the knock-offs.

phil funk/ liteguy10
I'm not SteelWolf so maybe you should wait for his reply thanks.

I'm pretty confident there's no 2032 cells in the AIT light. That said, those lights are cute toys but aren't very sensible as emergency lights if you have the slightest bit of preparedness. If you're the least bit of concern about such things, your first priority should be setting aside 5 gallons of water per person in your household, and rotating it at least once a year. People in Louisana right now are still dealing with dehydration and starvation, infection, illness, etc. Flashlights are a long way from their most urgent priorities.

If you're going to store and rotate water and other supplies, you can certainly put aside a couple spare flashlight batteries (lithium for extended shelf life, or alkaline and yearly rotation with your water). As I've mentioned a couple other times, relying on a shake light to avoid the need for batteries makes about as much sense as getting a wind-up wristwatch for the same purpose. Some people buy wind-up watches because they're watch buffs, and that's a good reason. People just wanting to know what time it is these days all use battery powered watches.

Get yourself a UK 2AAA eLED or Gerber Infinity Ultra or PT Attitude even one of the original CMG Infinities ( www.batterystation.com/cpf.htm still has a few of those left) and you'll have
20+ hours of light per battery change, and these lights are all $15 or less. Or get a PT Aurora for $25 or so and have a variable brightness handsfree light. Or get a bag of TWENTY Countycomm coin cell lights for $20.00 and have plenty of lights to give out to your family and neighbors.

Re solar charging: see
http://www.camerareview.com/templates/sunny16.cfm
It shows camera exposure settings going from f/16 on a sunny day to f/5.6 in heavy overcast. That's a 3 stop difference, which means 8x as much light in sunny weather as overcast. I'd increase it by at least 2 more stops for an actual storm.

Bottom line is that a solar charger can be useful for a very extended outage. Usually, emergency response will be much faster than solar chargers will become useful in. It's slow in the current Hurricane Katrina situation for what I think are unusual political reasons.

Alkaline batteries are cheaper to stock in extras for outages than dealing with solar cells and shake lights. A single led at spec takes about 20ma and alkaline AAs have close to 3000ma so a 3AA single LED light could last up to 150 hours off a set of batteries... you can buy about 30 AA alkalines on sale for around $10 if not more. This is perhaps the price of a shakelight or solar cell setup if not cheaper with no waiting or hassle (exersize).

I would agree on getting a light with a single LED and stocking up on batteries would be the easiest thing to do. Personally I like the PAL, not running at full it will last 100 hours easy and is brighter then either of the shake lights I own even at that level.

Having said that I do use NiMH in 90% of my lights and recharge then via solar. My solar setup is 4 KC120 (480w) panels and 8 Trojan T125's set up for 900amps at 12v. Then I use MAHA 401's or vanson for C and D cells. I can charge anytime day or night from the battery bank. The worst day in the last year during a storm was 24 amps or 275 watts, my best day was 231 amps or just over 3000w, so with heavy clouds I lost 90% of the power.

900amps? I never heard of arcwelding with solar cells.

It looks like AIT are the original inventors of the shakelight. So yes, I would trust the product. I bought mine quite a few years ago, probably the original Shakelight they had up for sale. But I don't have it with me, so I can't check.

I had no idea they had improved the product so much. I'm almost tempted to get a new one.

But it is true what the others have said. Flashlights and radios don't really consume so much power that stocking spare cells for them would be much of an issue. However, that wasn't really what started the topic.

Solar power is one aspect of disaster preparation to consider and it would be good to have a system that is capable of recharging your batteries even if the amount and intensity of sunshine is less than ideal. This means that the minimum voltage to start recharging must be met, no matter how much or how little actual currrent is available.

Say Steel Wolf, you stated "copycat manufacturers who used Cr2032 cells to make it light, but naturally it can't recharge". But what about their shakelights NOW?! I tryed contacting them again and no response, yet.

Paulr, Do you have or had a shake light from AIT? If so, ever take it apart to see if there's cells inside or just a capacitor? eh? If there's just a capacitor, I wonder how much "electricity they hold" and just how many minutes do those shake lights last (??). I went to Brock's LED flashlight page and clicked on http://www.palights.com/ Their flashlights are interesting. I wonder if there's rechargeable 9 volt batteries? If there is, i bet it'll take another $40.00 outta my pocket and wallet. I just recently bought at Radio Shack one of those 15 MINUTE CHARGER s that uses either the I-C3's or one can use regular Ni-Cad's or those Metal Hydride batteries. One can't recharge all THREE different batteries at the same time. Won't work that way. Says so in the instructions. I take a lot of pictures with my digital camera or use Krill Lamps for night lites when the power goes out..Robt

Lynx Arc, Solar Laser!

Say guys, i watched a science documentary about the history of solar power. Towards the end of the show, they discuss the possibility of solar powered laser weapons in the future. A scientist modified one of those "search lights" the stores use at their grand openings at night and one can see the parallel beam several miles away. (I myself as a kid in Southern Calif, lived near the Buena Park Mall and could see the beams at night thru the pollution). Anyway, the scientist has a YAG laser head at the focus point and with a fiber optic "tube" points the tube at a sheet of 1/2 inch steel 100 feet away and melted a hole right thru it in a split second! That was incredibly powerful... Robt

Robt said:

Say Steel Wolf, you stated "copycat manufacturers who used Cr2032 cells to make it light, but naturally it can't recharge". But what about their shakelights NOW?! I tryed contacting them again and no response, yet.

Click to expand...

Sorry, I don't understand the question. What about WHOSE shakelights now? As I mentioned before, there are a couple of copy shakelight manufacturers who seem to have done a proper job of it and used supercaps. There are a few who seem to have used CR2032s. This is still happening now. AIT appears to be the original inventors and makers of the shakelight. I trust their products anytime. And IMHO the runtimes for the new generation of shakelights listed on their website can be trusted as fairly accurate, within maybe 10% due to manufacturing tolerances. IIRC, the original Nightstar Shakelight I had was touted as running for 10min after 30sec of shaking. I remember testing it out and finding that while it did stay lit for over 10min, the brightness had dropped to 50% after about 5min. There is no regulation. It is just the supercap connected to the LED. No fancy regulation electronics in between. Not that there is a need to.

RobT said:

I wonder if there's rechargeable 9 volt batteries?

Click to expand...

There are rechargeable 9V batteries. The regular stuff you find in most shops will come up to 7.2V (6 x 1.2V), maybe 8.4V hot off the charger. There are a couple in electronics hobby shops which seem to have an extra cell or something because they are rated 8.4V nominal. I'm going to have to get one to try.

9V batteries can't be quick-charged like IC3 cells because they have several cells inside joined in series. It increases the likelihood of blowing up the pack if you try to pump too much current through it too quickly.

...or use Krill Lamps for night lites when the power goes out.

Click to expand...

Yep, I really love the Krill lamps too. Nice soft glow. I think, though, that LEDs, in the correct setup, are more energy efficient. Just stick them in a short acrylic rod with a roughened surface for that glow.

I do use 9v rechargeable's in all 7 of my pal's. I charge them once a month.

I forgot about another great little light that actually works. The free-light http://www.tadgear.com/x-treme gear/flashlights main/free_light_2.htm. It is a little larger then the Photon and has a small solar panel on it. While I haven't pulled it apart I have run it dead, left it in the window and it works again. I ran it dead (until it starts to blink) three times, probably not a good idea I wanted to know if it was really rechargeable. The newer version even has different light levels. Great for the kids, that is if they won't try to eat it

Re: Here the website Steel Wolf..

You asked WHOSE shakelights now? The website is:

http://www.generationgear.com/products/shakelight_comparison.html

The firm is located in BC Canada. Check out the website and tell me what YOU think Steel Wolf. I'm in NO rush for new types of flashlights. I get as much info as i can on these website forums and CPF is one of the best I ever been to for info. Brock, I've checked out the websites you mentioned. I might need to get a 9Volt charger if i get a PALIGHT from the firm.. Robert..

Re: Here the website Steel Wolf..

Robt, I've played with the AIT shakelights but wouldn't buy one except for amusement purposes. They are well made but I'm just not concerned about being stuck without a light due to lack of batteries. I am confident that they do what they say, however, and they don't have batteries inside, unlike some of the fake ones. They put out a reasonable amount of light for a minute or two after a few seconds of shaking. Then just shake again.

I just wouldn't waste money on these things though. They are toys, regardless of the emergency preparedness marketing nonsense. For $40 you can buy a heck of a lot of batteries. My friend who has the shake light that I played with calls it a "wank light" because of the hand motion involved in charging it up. That is a good description.

Yes, there are 9v rechargeables. Some of them have six cells inside (7.2v) and the better ones have seven cells (8.4v). The specs should say that.

If you want a very tough, long-running emergency light, try a Tek Tite Trek Lithium, $25 or so from batterystation. It's direct drive using a 3.6 volt lithium primary computer memory battery and will run for 200+ hours without dimming much (see review at the LED museum). By the time you use a wank light that many hours, your arm will have fallen off.

More sensibly, take a look around your house and count how many useable AA cells you can put your hands on, even not counting your stash of new ones. Let's see, there's a couple in the Walkman, one in the quartz clock on the wall, a couple in the cordless computer mouse, a couple in the radio, you get the idea. If you have a 1-led AA powered light like a CMG Infinity ($10 at Batterystation) you can run it for a heck of a long time just on batteries that you can scrounge.

Finally, if you're thinking about long term outages, don't forget your vehicle (mentioned before, I think). Why worry about how many days it takes to charge your AA NiMH cells with a solar charger, when you can charge from your car's cigarette lighter socket in 15 minutes?

Re: Here the website Steel Wolf..

Sorry RobT. I don't have any experience with the Generation Gear lights. And for these types of lights especially, experience is all you can count on. There are just so many variables.

The number of windings and the strength of the magnet determine how much power you can harness from each shake. The rectifier impacts on power loss. Most supercaps I've seen don't charge well on the rapidly changing current, so a smaller electrolytic cap is needed to smooth out the incoming power. The capacitative size and quality of these caps can vary by quite a bit, even within the same brand and manufacturing batch. The caps determine how much power you are able to store and how much power can be delivered to the LED. Finally, the quality and rank of the LED determines how efficiently your available power is converted to light, hence, how long you get usable light.

All I can say from experience is that 1F will just about power an average LED for 5min of "usable" light, useable being about the brightness you get driving an average LED with 10mA to 15mA. After about 5min, it really is too dim to be much use.

Therefore, if they are claiming 60min, they are going to need about 12F. That is, physically, quite a large capacitor. I'm not sure I see a mass big enough to be such a capacitor, but I could be wrong. Also, they represent it as being brighter than the Nightstar Shakelight 2. That is very bright for a shakelight and could indicate an even higher power requirement than what I noted above. (BTW, you could do a load of calculations to find it out, but I'm not ready to go in all that at this hour. )

However, as paulr noted, shakelights aren't really all that bright. In the first minute or 2 after shaking, my shakelight barely stood up to the original CMG Infinity. So they are fairly dim.

The only place I keep a shakelight is in my car. While I do have normal lights that use batteries, the incredible heat of summer here means that even lithiums don't survive long. So I keep a shakelight just to be prepared.