Homepage - RF Cafe
Webmaster: Kirt Blattenberger | KB3UON | Sitemap | ©1996-2014     Visit RF Cafe on
      Menu below is just a small sample of what is here!          Visit RF Cafe on Facebook Visit RF Cafe on Twitter Visit RF Cafe on LinkedIn
Custom Search
More than 10,000 searchable pages indexed.
•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

How do you charge a laptop battery with a solar panel ? - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.



kbarb
Post subject: How do you charge a laptop battery with a solar panel ? Posted: Thu Jul 16, 2009 1:33 am

Lieutenant

Joined: Tue Dec 30, 2008 1:53 pm
Posts: 4
I'm thinking of trying to charge my Lenovo Thinkpad x60s battery with an R-14 Powerfilm flexible solar panel.
I hope this question is not too elementary for this august forum.
Anyway, the idea is to charge the battery with it in the laptop, but with the laptop turned off. I think having it turned On will most likely not work (as follows.)

Someone told me that since the wattage of the solar panel is much less than the draw of the Thinkpad, it won't work. I'm not an electrical engineer, although I did quite well in physics. The only problem is, it's been quite a few years (of disuse.)

Here are the numbers :

R-14 Powerfilm
The Powerfilm is rated at 15.4V and .9A ( ~14 watts)

Lenovo Thinkpad X60s Laptop
The battery is 14.4v / ~5200 mAh
I measured the current draw of the Thinkpad - when OFF (battery charging only) - at .25A and 115v (= 29watts ).
When On, it's something over 50 watts.
I measured this straight out of the wall, before the inline transformer that converts the 110v to ~20v (?). (I'm not sure what the charging voltage is, but the charger says 20v / 3.5A = 70watts - probably what's need to actually power a running computer)

I had thought that the battery charging would charge at a much lower current, like a trickle current, .1C or so, but this is not necessarily the case with Lithion batteries it seems. See Lithium Ion Battery Charging Basics
It's more like .2 to .7C actually.

One idea, if this is not going to work, is to pull the battery off and charge it outside the laptop, but this looks complicated as there are about 8 or 9 contacts on the battery, and I have no idea what is what. It sounds a little risky anyway.

If anyone could be of help that'd be great.

Thanks,
Kent


Top

Kirt Blattenberger
Post subject: Re: How do you charge a laptop battery with a solar panel ?Posted: Thu Jul 16, 2009 3:41 pm

Site Admin


Joined: Sun Aug 03, 2003 2:02 pm
Posts: 308
Location: Erie, PA
Greetings kbarb:

If you don't mind spending a few bucks, you might get away with buying one of the chargers made to plug into a car cigarette lighter and interfacing it with your solar panel. The voltage specs seem to agree well. Should be a simple 2-wire connection between the two devices.

This one is made for the ThinkPad
http://www.batterymart.com/p-ib1107-10-laptop-car-cord.html



_________________
- Kirt Blattenberger
RF Cafe Progenitor & Webmaster


Top

kbarb
Post subject: Re: How do you charge a laptop battery with a solar panel ?Posted: Fri Jul 17, 2009 1:29 am

Lieutenant

Joined: Tue Dec 30, 2008 1:53 pm
Posts: 4
Yes, I have one of those bookmarked actually.
In fact a few months ago I bought an inverter to plug into the cigarette lighter, and now I'm thinking I should have just used one of those.
But this time I'm powering off the solar panel.

And it still seems to me that the laptop will try to draw more than the panel will deliver.

That's what I'm trying to figure out actually, if someone can fill me in.

But thanks, nevertheless.

Kent







Posted  11/12/2012
A Disruptive Web Presence

Custom Search
Over 10,000 pages indexed! (none duped or pirated)

Read About RF Cafe
Webmaster: Kirt Blattenberger
    KB3UON

RF Cafe Software

RF Cascade Workbook
RF Cascade Workbook is a very extensive system cascaded component Excel workbook that includes the standard Gain, NF, IP2, IP3, Psat calculations, input & output VSWR, noise BW, min/max tolerance, DC power cauculations, graphing of all RF parameters, and has a graphical block diagram tool. An extensive User's Guide is also included. - Only $35.
RF system analysis including
frequency conversion & filters

RF & EE Symbols Word
RF Stencils for Visio

Product & Service Directory
Personally Selected Manufacturers
RF Cafe T-Shirts & Mugs

RF Cafe Software

Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel
Your RF Cafe Progenitor & Webmaster
Click here to read about RF CafeKirt Blattenberger... single-handedly redefining what an
                                 engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem! (Seize the Day!)

5CCG (5th MOB): My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website