laptop battery challenge

Batteries, Chargers, and Battery Management Systems.
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cerewa   100 W

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laptop battery challenge

Post by cerewa » Aug 14 2009 1:52pm

Seems like a lot of the folks on this forum know how to accomplish some pretty awesome stuff with electronics, so I wanted to offer a challenge.

I know a number of Haitians who use laptop computers off-the-grid in Haiti.

Small solar panels are not particularly expensive, but the cost barrier to getting electricity for your laptop in Haiti is fairly high. I think a number of people on this forum would have an easy time solving this problem, though:

What people do in Haiti currently is this : install 12V solar panels, install some large and expensive lead acid batteries with a charger, and then install a (small inexpensive) inverter to provide 120V AC power, which is converted back to 9.5V DC* for use with a laptop computer.

*I'm saying 9.5V DC, but actually the converters I've seen are either 9.5V DC or 19V DC. However, the ultra low cost netbooks, which also run off of very little power, are made for 9.5V DC. This is what I think is most appropriate for folks who can't spend a lot on a computer or on powering a computer.

So does anybody know how to make a pulse-width-modulating voltage regulator (or something else?) to allow a netbook made for 9.5V DC to run off of a nominal-12V solar panel (apparently 12V solar panels actually produce up to 17+ volts in bright sun)?

If you can do it cheaply, I'd be happy to pay for such a voltage regulator. Or if you can explain how to make one to someone who isn't much good at assembling electronics and hasn't a clue how to create a circuit board, that'd be cool too! :-)

Oh, and if any of you want to try an ultra-low-cost off grid setup for a laptop for yourself, check this out:
EEE PC for less than $140
10W solar panel for less than $40, able to provide enough power to charge EEE PC battery in a reasonable time

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vanilla ice   100 MW

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Re: laptop battery challenge

Post by vanilla ice » Aug 14 2009 4:10pm

Something like this might work.

http://cgi.ebay.com/Wall-DC-DC-Converte ... 7607464587

This one with two panels in series. But I'm sure you could find one spec'd for 12-18v input. They are pretty efficient.

You might even be able to run the standard 110v power supplies off of a couple of panels in series. Panels can be run in series right? Or if not deep cycle lead bats in series.

nutsandvolts  

Re: laptop battery challenge

Post by nutsandvolts » Aug 14 2009 5:59pm

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Last edited by nutsandvolts on Oct 16 2009 11:54pm, edited 1 time in total.

heathyoung   1 MW

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Re: laptop battery challenge

Post by heathyoung » Aug 16 2009 8:11pm

Check out national semiconductors 'simple switchers' - 50W output, minimum parts cound, online component calculator. Preferably with an inexpensive 12V SLA to cope with shadows etc - if you could source enough power from the panels, this could be deleted.
GNG offroad build on Craftworks DHR with 12S2P lipo. Light, balanced, powerful, able to climb a tree.
Project Vectrii (2) - status - Finished. Nope. 38S Leaf cells are next. Now have 2 of them - Averages 50Wh/Klm

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dak664   1 kW

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Re: laptop battery challenge

Post by dak664 » Aug 17 2009 7:17am

Here's an instructive page, although not at the power levels you need. A 50 watt buck charger using pwm from an ATTiny85 would run around $10 in parts. Soldering is not necessary if you use a breadboard (this one has two chargers). As a bonus it can connect through USB for logging. More details at http://www.avrfreaks.net/index.php?name ... ic&t=71196

nutsandvolts  

Re: laptop battery challenge

Post by nutsandvolts » Aug 18 2009 6:24am

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Last edited by nutsandvolts on Oct 16 2009 11:54pm, edited 1 time in total.

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TylerDurden   100 GW

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Re: laptop battery challenge

Post by TylerDurden » Aug 18 2009 9:42am

nutsandvolts wrote:... but I am looking for a good way to regulate 12V at high amps for these: Small black projector fog driving lights
You can run those in series.


You can get the par16 led's for under 20 bucks, and save a lot of juice. 3w each.
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monster   100 kW

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Re: laptop battery challenge

Post by monster » Aug 19 2009 7:11am

if all you want to do is loose 7.5 volts then why not just dump it over a resistor (light bulb)?

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TylerDurden   100 GW

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Re: laptop battery challenge

Post by TylerDurden » Aug 19 2009 7:33am

12V "universal" adapters are quite common, for using electric toys in the car.

12V in, 9V out. (It might even be more like 9.5 or 10V out.)
12V_DC-DC.jpg
12V_DC-DC.jpg (50.5 KiB) Viewed 309 times
http://www.walmart.com/catalog/product. ... d=10746815
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TylerDurden   100 GW

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Re: laptop battery challenge

Post by TylerDurden » Aug 19 2009 7:37am

This one is pricey, but has a 10V selection.
http://www.walmart.com/catalog/product. ... gMethod=rr
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