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Participant

Join Date: Mar 2009
Posts: 1

Charging Laptop Batteries with Solar Cells

04/01/2009 3:03 AM

Hi Guys!

Will anyone help me with some questions I have about charging laptop batteries with solar cells?

I want to make a homemade solar charger as compact as possible. I want to know how many mono-crystalline solar cells (each cell is .5v, right?) it would take to charge a typical Lithium Ion laptop battery in 5hrs. How small could I make it?

I was told that I can cut cells (making the whole module smaller), wire them together and up their voltage. Can anyone help me to understand/provide a diagram of how to do that?

I would greatly appreciate it if anyone could offer any assistance.

Many thanks in advance!

Julie

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Pathfinder Tags: battery charge solar
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Guru
Popular Science - Biology - life lover Hobbies - Musician - music lover Safety - Hazmat - better safe than sorry United Arab Emirates - Member - desert trek Technical Fields - Procurement - procurement

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#1

Re: Charging a battery with solar cells

04/01/2009 4:17 AM

Hi jadejulz,

another DIY fan. :D

look it up from here:

google for more!

HTH!

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Associate

Join Date: Mar 2009
Location: Ras Al Kaimah
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#2
In reply to #1

Re: Charging a battery with solar cells

04/01/2009 8:17 AM

page cant open. help me pleese.

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Anonymous Poster
#3

Re: Charging Laptop Batteries with Solar Cells

04/02/2009 1:13 AM
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Guru
Australia - Member - New Member Engineering Fields - Mechanical Engineering - New Member

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#4

Re: Charging Laptop Batteries with Solar Cells

04/02/2009 7:29 AM

If you follow this link you will have a circuit. http://www.discovercircuits.com/H-Corner/solar-batt-chgr.htm

Do not try cutting the cells they are brittle , you can buy many different sizes, but do not use any that are larger than necessary or power will have to be dissipated as it is not good to overcharge lithium cells it can be dangerous .

google up some studies on Lithium cells and charging before making anything up.

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Power-User

Join Date: Apr 2008
Location: Indiana
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#5

Re: Charging Laptop Batteries with Solar Cells

04/02/2009 9:13 AM

Here is the specs from a pre-made solar charger for laptops.

  • 830mAH current output
  • DC 6V output voltage
  • Lithium polymer battery
  • 8 - 10 hours of charging time

12V averaged 4 - 5 hours charge time on most solar chargers.

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Anonymous Poster
#6

Re: Charging Laptop Batteries with Solar Cells

04/02/2009 10:19 AM

go to harborfreight they sell for 39.00

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Commentator

Join Date: Apr 2008
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#7

Re: Charging Laptop Batteries with Solar Cells

04/02/2009 3:03 PM

If you want to do it yourself and make sure it works, check the output voltage and current on your wall plug converter. Simple math and circuit design after that.

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Power-User

Join Date: Oct 2007
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#8

Re: Charging Laptop Batteries with Solar Cells

04/10/2009 10:32 PM

hello,

i am going to beg the question. you should not do this. it is the wrong approach. you should use standard solar panels. voltage does not matter. then buy a "Lind" Dc to Dc converter. i have done the math. i have also done the dollar math. "Lind" is the answer. just call them up. tell them what laptop you have. they will sell a converter. most are 12 volt, but other voltages are available. my girlfriend makes her living off of her laptop and cell phone. i was faced with adding two more solar panels to keep up with her power demands. by switching instead to a dc to dc converter, i did not have to add panels. cost difference, lets see two more panels would have been $1500. Lind converter $100. i think i chose the better way.

by the way the math is as follows. if you use solar panels and the standard power adapter, then what you need to compare is the difference between changing the 12 volt from your batteries or solar panels to 110 at 65 percent efficiency. then running it thru the power adapeter again at 65 percent efficiency. wound up i was using almost 200 watts per hour for a computer that was pulling 50 to 70 watts depending on weather it was charging or not. the lind is 95 percent efficient. that means i am pulling 55 to 77 watts per hour. my battery bank almost never runs out of power now.

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