How Do You Charge a Laptop Battery with a Solar Panel ? - RF
Post subject: How do you charge a laptop battery with
a solar panel ? Posted: Thu Jul 16, 2009 1:33 am
Joined: Tue Dec 30, 2008 1:53 pm
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 :
is rated at 15.4V and .9A ( ~14 watts)
Lenovo Thinkpad X60s
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
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.
Post subject: Re: How do you charge a laptop battery
with a solar panel ?Posted: Thu Jul 16, 2009 3:41 pm
Joined: Sun Aug 03, 2003 2:02 pm
Location: Erie, PA
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
- Kirt Blattenberger
Progenitor & Webmaster
subject: Re: How do you charge a laptop battery with a solar panel
?Posted: Fri Jul 17, 2009 1:29 am
Tue Dec 30, 2008 1:53 pm
Yes, I have one of those
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.
what I'm trying to figure out actually, if someone can fill me in.
But thanks, nevertheless.