best solar charger right now? march 14″

[Bob Gross]

The problem with that last one is that you don't know how much replenishable power is coming from the solar panel, and how much is coming from the internal battery. Those solar charger marketing guys don't miss a trick.

–B.G.–

[michael levi]

It says it can charge a device while charging itself in the sunlight. But yes upon looking more into it its made to charge by plugging into a wall? What is the point of the solar panel then? I dont know. ill keep looking.

I want something small and light that can charge itself, and that has a built in battery with decent juice. Or else I would always need to have my device plugged into the solar panel if it didnt have a battery itself.

hmm, all I need is a 8 ounce solar charger, it would be nice if it had a built in battery. I dont know what I want honestly, I didnt realize how many configurations there can be. If anyone knows what I need/ good setup let me know please!

[Nick Gatel]

Solar for Backpacking?

[Glenn S]

That little battery you linked to has a solar panel, sure, but run the numbers on it.

It's a 7200 mAh battery. The panel puts out 180 mAh MAX. So even in direct sun, running at peak efficiency, it would take 40 hours to charge up that battery. At 10 hours of high-noon desert sun, that's 4 days.

The reason you can't find quite what you're looking for is the same reason we can't either. It doesn't exist yet.

For 8 ounces, you can have either a decent panel, or a 7000 mAh battery, but you won't get both. Wish it wasn't so, but that's where it stands as of today.

On the upside, if you're going to spend 8 oz on a 7 amp battery, one with a little solar booster is the way to do it.

[Bob Gross]

If you have a solar panel set up in Nick's backyard where sunlight is highly reliable, you might put up a solar panel without any intermediate battery, and just charge your devices directly. However, if you are in more normal places where there is some sun and some shade and some clouds, then often you can't get a high enough current coming out of the bare solar panel to charge your devices. In that normal case, putting the intermediate battery in there will help your charging operation continue. But, if you don't ever know how much power your solar panel is capable of, or if you can't separate that power from the battery itself, then you are just spinning your wheels.

If the solar panel specs say that it will produce 5 watts or 10 watts, then that is a hard number that means something. You will still need to get some direct sun to produce that wattage, but that is a good target to shoot for. For a backpacker-size panel, something like 5 watts or 10 watts is what you might be looking for.

On the other hand, if you cut your overall electrical usage down, you might be able to complete your trips with just one spare battery carried, or something like that. But if you don't even know what your overall electrical usage is, you are still just spinning your wheels. Statements like, "it's to run an XYZ smartphone" are absolutely silly.

–B.G.–

[Nick Gatel]

Michael,

You said, "I am really not wanting to spend hours teaching myself about these and reading reviews."

and

"…all I need is a 8 ounce solar charger, it would be nice if it had a built in battery. I dont know what I want honestly, I didnt realize how many configurations there can be. If anyone knows what I need/ good setup let me know please!"

It doesn't work this way. First you MUST determine how much energy you use each day. Even if two people have the exact same phone and/or devices, they energy use will vary because they are not going to use them the same.

Then you need to estimate how much power you need to put back each day. It can be less than you use, depending upon how long your are out.

Then you need to guesstimate how much energy you can realistically generate each day, which varies by where you are, what the weather is, what the time of year it is, your orientation to the sun, will you stop for maximum sun exposure, etc., etc., etc.

No one can answer these questions for you.

I have a trailer that we camp in for up to 2 weeks at a time. It is solar powered. I have to have a strategy to cover sunny days or two weeks of overcast skies. Too little sun for too long means I have reduce my consumption. Sunny days in July means I can do anything I want to include running a microwave, toaster, blender, and a 32" Television with a DVD to watch a movie. But I know how many amps have been consumed and how many amps have been put back in.

You are going to need to make an effort in this search.

[michael levi]

Nick, I will be using about %75 of a 3,200mAh battery per day. This is a Smasung Galaxy mega 6.3. Hope this helps, thank you!

[michael levi]

http://www.amazon.com/Opteka-BP-SC6000-Capacity-Charging-EcoPanel/dp/B00CHQI57A/ref=sr_1_6?s=wireless&ie=UTF8&qid=1394775713&sr=1-6&keywords=solar+charger+usb

The one above is a 6000mah battery with a solar panel. $29.99

I imagine it will take a while to charge, but once charged it holds a lot of power. Is this what I want? Not sure.

[michael levi]

http://www.amazon.com/Poweradd-trade-Apollo2-10000mAh-Dual-Port/dp/B00FXWGRHU/ref=sr_1_17?s=wireless&ie=UTF8&qid=1394776322&sr=1-17&keywords=solar+charger+usb

This one ^ is 10000mah and $45, seems super compact and 9oz, seems good?

I doubt the solar panel works fast, but with a battery that big I wont be relying on the panel as much right?

[Bob Gross]

Here is a good rule of thumb for solar panels:

You can get about 10 watts of output from about one square foot of panel. Some are better than this, and some are worse. If you are looking at a product that doesn't produce 5 or 10 watts, you are probably looking in the wrong direction.

One guy calculated that he needed a 5 watt solar panel to meet his device power needs. Then he did the JMT and complained afterward that the panel didn't work worth a damn.

The problem was that he had it hanging off the back of his backpack, so it was facing north most of the time while he was headed south. If he had planned on taking several zero days with the panel facing south, he would have gotten completely different results.

–B.G.–

[Glenn S]

"I imagine it will take a while to charge"

No need to imagine, it's rated at a maximum 250mAh charge rate from the panel. A 6000 mAh battery would take 6000/250 = 24. So 24 hours of full sunlight to charge it.

"but with a battery that big I wont be relying on the panel as much right?"

Again, no need to guess at this stuff, it's all pretty straight forward. You said you would be using 75% of your 3200 mAh battery per day, that's 2400 mAh, or about 25% of 10000. So it would be good for four 75% charges.

You'll never get optimum solar charging rates, and you'll never get precise battery drains, but good ballpark figures are really just that simple, once you know what your requirements are, like others have stated.

Just be sure when doing battery and panel comparisons, that you're using the same voltage specs, in this case 5 to 6 volts. It's a pretty standard range for the type of application you're looking into.

[Glenn S]

Just to chime in and emphasize what others keep saying, too many people think that solar panels work from some sort of wizardry, or elvish magic. They think as long as the sun's up, there's free power flowing through the wires at maximum rated capacity. There's this belief that's it's as regular as a wall socket. Nothing is further from the truth.

A solar panel in the shade makes about as much power as a wind generator on a calm day. It just doesn't happen. Oh sure, it may make an itty bitty tiny miniscule amount just from ambient light, but unless it's in DIRECT sunlight, any of these little panels just don't do much of anything.

So all the ratings and specifications in the world don't mean squat, unless you factor in all the variables involved. Solar is unreliable at best, which is where batteries come in. The battery is the buffer, to keep the juice flowing. Whenever constructing any kind of solar system, big or small, you have to build from both ends, increase production and reduce consumption. It's a balancing act, and the battery is just the middle man.

[michael levi]

Lots of great info. thanks for the replies.

I think im going to get this apollo2 10kmAh battery pack with solar. If it will charge my phone 4x I should have plenty of time to keep it charged within 4 days with the 250 or 200 solar charge time. Very compact and good juice.

It also has a flashlight and a carabiner and looks like it belongs outdoors. Seems legit. 9.4 ounces. I like it…

http://www.amazon.com/Poweradd-trade-Apollo2-10000mAh-Dual-Port/dp/B00FXWGRHU/ref=pd_sim_sbs_e_2?ie=UTF8&refRID=0REKCGZN4BH8AFJFMTWY

[Glenn S]

I looked into this battery panel charger thingy a bit more. I've not looked into these types of devices before, so I don't know if they're all this way or not, but as I was mentioning about making sure the volts are the same to get reliable information…

It appears to use a pretty common 3.7 volt type of lithium battery. So that makes the 10k mAh rating a bit misleading, since it actually takes about 5.5 volts to charge a USB device.

What that means in the math, is that the 10000 mAh, multiplied by the voltage of 3.7, gives you a total wattage of 37000. Divide the total wattage by the OUTPUT voltage of the USB's 5.5 used by its microcircuitry, and you only get about 6800 usable mAh's.

In short, Amps X Volts = Watts.

So with the magic of marketing, a 10,000 mAh battery, is really only usable for 6,800 mAh's for a USB device.

I know that sounds rather convoluted, but bottom line, is that it's REALLY only about a 6800 mAh battery for your phone.

One of the reviewers on Amazon was complaining about it not being true to spec, which is what made me suspicious and look a little deeper.

Perhaps somebody else can verify these findings, but that's how it looks to me.

[michael levi]

Interesting observation Glenn. I wonder if all of these from various brands agree like that. Meaning they are all misleading.

Still, if it has 6800mAh then that might be enough for my application. It seems like this should work, the next jump is a bigger 23000mAh and $115 +.

I feel like I will be able to take advantage of the small solar panel on the Apollo 2 with the plentiful sunlight on the islands. Only one way to find out is to test it, I'll probably buy one sunday!

[James Marco]

Well, solar chargers are of interest, but only as more permanent pieces of hardware. With todays technology, they do not pay for hiking. In most cases, a 4 pack of lithium AA bateries will last as long for less weight. If you were hiking with plenty of sun on most days, you *might* keep up the charge on a phone. Otherwise, you need an external battery as you mention. If you carry the weight of a battery, why deal with a solar charger and electrical circuitry? For two to three weeks out, just have a check-in time. Turn it off the rest of the time.

In the ADK's we don't have much service, 'cept near a town. My phone doesn't work for a week or two at a time. ONLY near towns (within a few miles) does it work. I turn it on to use the camera, of course, but that's about it. I let my wife know, and she doesn't get worried, unless I don't contact her for a full week. I used to use a pay phone, but these went away a few years back and I was forced to get a cell phone.

[Koen Derks]

Finally! Yes you can't compare mAh's from a 3.7 volt battery with a different voltage. It's not totally to blame us from forgetting our high school classes, 'the powerbank market' is just totally vague.
Some more information about calculating the energy needs for your backpacking trips: http://www.multipoweredproducts.com.au/pages/How-to-calculate-your-solar-power-needs-whilst-travelling%3F.html
Example:
1 powerbank of 5200 mAh. Lithium batterypacks mostly have an internal voltage of 3.7V (It's not written on the pack itself and apparently different from the output voltage) So 5.2 Ah x 3.7V = 19.24Wh.
How many times can I charge my 7.6V 1130 mAh camera battery?
1.130 Ah x 7.6V = 8.59 Wh. 19.24Wh/8.59Wh = 2.2 times….. almost! Charging batteries isn't efficient. The heat from charging batteries = energy loss. So keep an efficiency of 75%(?) in mind. And not all manufacturers are honest in their specifications…..

I'm currently exploring the market if a solarpanel is something for a coming trip in the mountains. Charging spare batteries(no powerpacks) in cabins or wherever every few days is still the lightest way to go. A massive batterypack/powerbank which you charge once in 2 weeks is about the same weight as the solarpanel+battery you would need for the same amount of energy use. Do you stay once in 2 weeks in a cabin with electricity? Go for a powerpack. Do you hike a lot in the sun and like the autonomy? Go for the solar panel.

[Glenn S]

This thread is what inspired me to try a little project. It's a cheap $31 Coleman (Sunforce) solar panel that's similar to a Nomad 7. I stripped it down to minimum weight and showed the results over in this thread.

[Jennifer Mitol]

"Do you stay once in 2 weeks in a cabin with electricity? Go for a powerpack. Do you hike a lot in the sun and like the autonomy? Go for the solar panel."

Koen, that's the absolute best summation/advice re the SOTM I've seen. Thanks for putting it so succinctly….and helping what I assume are a whole bunch of us who honestly still believe electricity is magic (and TV, too for that matter…how does that video get to my little box??!!!)

I'm a relatively smart person, but I'm just flummoxed about these battery/solar packs. Thanks to all of you for your patience in continuing to explain the same things over and over to us…each time a little more seems to sink in!

And no, I'm not being sarcastic…and yes, I'm one of those electricity-is-magic! people, too.

[Adam S.R.]

The exact weight of the Suntactics sCharger-5 has been changed since it has metal grommets in the corners:

8.3oz
235g

Adam
Suntactics Customer Relations

[michael levi]

The solar charger I bought at the beggining of this thread was, how should I put this. Insufficient and it died for 2-3 days on the trail before I was near a power supply/ outlet. Granted, I did not have it in direct sunlight that much but I lazilly attempted. It can be a lot of work moving it in the sun when dealing with shadows, angles, and rain.

It worked good as a battery pack that charged my huge phone up 2+ full times. I looked at the solar as a bonus feature, however slow, it did work. Good "just in case", which we all HAVE or WILL be there someday.

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