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lash

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Posts: 11
Reply with quote  #1 
Hey,

I use an laptop that takes 20V/3.5-4.5A (battery says 11V/4.4-5.3A). Is there a consumer grade and portable solar panel I could get that (in sunlight) could enable me to run the laptop on it while working without running out of power?

I presume I would need some battery inbetween for stability. Could I use the laptop battery, or would I need some other special device?

Thanks.

Rick H Parker

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Reply with quote  #2 
There are a couple of options for powering directly off a solar panel but, lets get your needs clearly defined first .. It would help if you tell your situation.

How much portability do you need?
Are you going to use it only when the sun is shining or would you want power after the sun has set?



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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
lash

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Posts: 11
Reply with quote  #3 
It should be something that could be brought leisurly to the beach, on a bicycle trip etc.

Ideally it would also have the capacity to keep the laptop battery charged so that the battery capacity could be spent after sunset. But first and foremost I'm curious about what alternatives are out there at all.
stmbtwle

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Reply with quote  #4 
You'll need a battery but the one in the laptop should be fine. Really what you'll be doing is charging that battery, just as you do when using an AC adapter.

The hard part is getting the proper voltage. If your battery is 11v then that will run your laptop, the 20v is probably for charging. A "12v" panel can put out up to 22v, but usually is more like 17, which would probably be enough to run your laptop and charge the battery.

What do you consider "portable"? Depending on your laptop you may need 60-100 watts, and solar panels that size while portable will NOT fit in a backpack. You could get SEVERAL smaller panels and wire them together, and stack them when not in use. Companies such as Harbor Freight have folding kits that may work, if they have the watts.

Considering the cost of laptops, I'd consult with the manufacturer to be safe.

A more portable setup would be a battery and a 12v adapter. You could charge the battery later from solar, your car, or from line power.

Rick may have a better idea.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
lash

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Posts: 11
Reply with quote  #5 
Quote:
What do you consider "portable"?


Portable would be something that fits in the same not-too-giant backpack I would bring my beach gear in, for example?

Quote:
Depending on your laptop you may need 60-100 watts


Yes, my power supply says 20V, 90W

Quote:
A more portable setup would be a battery and a 12v adapter.


Does that mean that I could theoretically run my laptop with a 12v adapter if I didn't have a battery in it?
Rick H Parker

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Reply with quote  #6 
Looking like a folding solar array is the best fit.
Check you laptop specs and see what the tolerance is on the 20VDC.

I am not recommending this one at this time but, it the general idea.
Don't jump the gun, the 80W claim is a accounting trick.








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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
stmbtwle

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Reply with quote  #7 
Random thoughts:

I have to agree with Rick on the wattage, the numbers you have are MAXIMUM values for the power supply and the battery.  What the computer ACTUALLY requires is still unknown, though it will vary depending on screen brightness, processing load, etc.  Not too sure how to determine it though.  You might plug the power supply into a "Kill a Watt" to get a ballpark figure.

Bear in mind the power supply is expected to run the computer AND charge the internal battery under all conditions.  If the battery is fully charged when you start, the load would be less.

The 100w folding solar kits appear to be about 2' square when folded, or a bit larger than a briefcase.  

I don't think you can run the laptop without the internal battery, but you could always try it by removing the battery and using JUST the power supply.  If you're going direct from solar, you WILL need the battery.  

You can get 12v AGM (sealed) batteries on Ebay or Amazon, price depending on the capacity. The bigger, also heavier.
https://www.amazon.com/ExpertPower-EXP1270-Rechargeable-Lead-Battery/dp/B003S1RQ2S/ref=sr_1_3?s=electronics&ie=UTF8&qid=1529086410&sr=1-3&keywords=12v+7ah+agm+battery&dpID=41Fe5%252BdRTzL&preST=_SY300_QL70_&dpSrc=srch
If you need more, you can always parallel two or more.  Lithium batteries are a lot lighter in weight but also more expensive.  Your call.

You can probably get a 12v "auto" adaptor for your computer, or you can get a small inverter and plug your power supply into it.  The latter is cheaper but more cumbersome and less efficient.  

Inverter:
https://www.amazon.com/BASEIN-Inverter-Portable-Converter-Charging/dp/B06XVXDZBN/ref=sr_1_19?s=lawn-garden&ie=UTF8&qid=1529085912&sr=1-19&keywords=computer+car+adapter

You might be able to connect the 12v adapter or inverter directly to your solar panel... 

Considering the variable nature of solar (shadows, clouds), you WILL need the internal battery.  It would be rather annoying to be computing away and some passerby stops to look at your solar panels (they invariably stand right in front of it) "Hey what's this?" (CRASH).

Adjustable power supply: 
https://www.amazon.com/gp/product/B00CNXLDCQ/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

Folding solar panel:
https://www.amazon.com/DOKIO-Monocrystalline-foldable-Inverter-Controller/dp/B0748GKHZ8/ref=sr_1_3_sspa?s=lawn-garden&ie=UTF8&qid=1529063760&sr=1-3-spons&keywords=folding+solar+panel&psc=1

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
lash

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Posts: 11
Reply with quote  #8 
Quote:
I don't think you can run the laptop without the internal battery


Actually I can. But yeah with unstable supply of power then without is no good as you say.


Quote:
Lithium batteries are a lot lighter in weight but also more expensive


What kind of lithium battery will deliver 12V? AGM batteries aren't exacly "portable" are they? Except in the same sense "mobile phones" were portable in the 80s? 😉

--

Thanks for the links, I will study!


jjackstone

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Posts: 52
Reply with quote  #9 
Modern laptop batteries are lithium. Is there any reason you can't just bring a spare fully charged battery with you and replace when needed?
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JJ
lash

Registered:
Posts: 11
Reply with quote  #10 
Quote:
Modern laptop batteries are lithium


I understand, you mean the internal battery. They usually have a small array of connection points, more than two. They have to be charged from inside the laptop / from a specialized device, no?

I assumed you meant some generic lithium battery, which was not big and clunky like the alternative.

Quote:
Is there any reason you can't just bring a spare fully charged battery with you and replace when needed?


1) it's outside the scope of the question here
2) One use case is a trip where there might be days between each grid charging opportunity
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