using laptop charger

[Paul Fox]

james wrote:
 > Shouldn't be destroyed.
 > 
 > Even if there is an overvoltage condition (beyond 24V), damage should
 > be constrained to a fuse on motherboard.

it's better than that:  24V is where we'll stop charging, and perhaps
stop operating -- but the laptop won't be damaged.  the laptop will be
fine up to 40V, which is when the fuse will blow: 
    http://wiki.laptop.org/go/XO_DC_Input#Overvoltage

paul

 > 
 > Attached microscope photograph taken facing the back of the DC input
 > connector.  Big white device with marking 3R is the fuse, silk screen
 > label PF2, replacement should be rated 3A at 125V.
 > 
 > Second set of pads is next, PF1, in parallel, possibly useful if your
 > fuse is a different shape.
 > 
 > For continued safety, please replace fuse with required rating, not a
 > nail or copper wire.
 > 
 > On Thu, Dec 12, 2013 at 11:48:21PM +0000, NoiseEHC wrote:
 > > Thanks for all the answers, I will let you know whether my XO 1.75
 > > will be destroyed by the Toshiba adapter... :)
 > > 
 > > 
 > > On 11/12/2013 20:29, John Watlington wrote:
 > > >James is correct about 19V probably not working with an XO-1, but with an XO-1.75/4
 > > >you should be fine up to 24V.
 > > >
 > > >When running with an input voltage higher than 13V, the battery charger on the
 > > >motherboard runs noticeably hotter.     Still within spec at 19V and 45C ambient,
 > > >but you might notice the difference in case temperature near the DC input plug
 > > >if charging an empty battery.
 > > >
 > > >Cheers,
 > > >wad
 > > >
 > > >On Dec 11, 2013, at 3:09 PM, James Cameron wrote:
 > > >
 > > >>G'day Andrew,
 > > >>
 > > >>There is a voltage above which the XO-1 will not charge, which had
 > > >>been often encountered by people using solar panels.  Along would come
 > > >>a cold sunny day, with a greater than normal voltage, and the charging
 > > >>would stop.
 > > >>
 > > >>I don't recall the actual voltage (Richard may remember), but I think
 > > >>it was somewhere near 18V, and it varied slightly between laptops.
 > > >>
 > > >>So it might work, or might not.
 > > >>
 > > >>Instead of using a resistor, you might use two or three large diodes
 > > >>in series, each of which will provide a "forward voltage" 0.6V drop.
 > > >>Pick the diodes based on the maximum current 1.85A (usually double
 > > >>that), and the power that will be released as heat; P = V x I, where V
 > > >>is 0.6, and I is not to exceed 1.85A, so 1.11W minimum "power
 > > >>dissipation".  Place them in a way that does not hold the heat in.
 > > >>
 > > >>https://learn.sparkfun.com/tutorials/diodes
 > > >>
 > > >>p.s. if you find one diode does what you need, then add another in
 > > >>case of variation in the supply or laptop.  You might even add a
 > > >>full-wave bridge rectifier instead of two diodes, that way the input
 > > >>polarity won't matter.
 > > >>
 > > >>On Wed, Dec 11, 2013 at 01:52:54PM +0000, NoiseEHC wrote:
 > > >>>Hi!
 > > >>>
 > > >>>I am thinking about using my laptop's charger instead of the OLPC
 > > >>>charger in the future as I move a lot and it's getting really
 > > >>>tiresome to bring both chargers with me. The plan is to create a
 > > >>>converter plug and use only the laptop's but it has different
 > > >>>voltage levels.
 > > >>>
 > > >>>laptop: TOSHIBA
 > > >>>part: PA3715U-1ACA
 > > >>>model: PA-1750-24
 > > >>>output: 19V - 3.95A
 > > >>>
 > > >>>XO-1.75: DARFON
 > > >>>model: BBOJ-C
 > > >>>output: 13.5V - 1.85A
 > > >>>
 > > >>>So can I plug my XO to the TOSHIBA adapter? The page says that
 > > >>>11-18V needed, while the laptop's is 19V. Shall I use a resistor to
 > > >>>drop the voltage or is it unnecessary? Power usage is not an issue
 > > >>>to me. (BTW I will use the plug from the XO-1's charger, I guess
 > > >>>that it did not change in the meantime.)
 > > >>>
 > > >>>Thanks,
 > > >>>Andrew
 > > >>>_______________________________________________
 > > >>>Devel mailing list
 > > >>>Devel at lists.laptop.org
 > > >>>http://lists.laptop.org/listinfo/devel
 > > >>-- 
 > > >>James Cameron
 > > >>http://quozl.linux.org.au/
 > > >>_______________________________________________
 > > >>Devel mailing list
 > > >>Devel at lists.laptop.org
 > > >>http://lists.laptop.org/listinfo/devel
 > > 
 > 
 > -- 
 > James Cameron
 > http://quozl.linux.org.au/
 > part 3     text/plain                 129
 > _______________________________________________
 > Devel mailing list
 > Devel at lists.laptop.org
 > http://lists.laptop.org/listinfo/devel

=---------------------
 paul fox, pgf at laptop.org