[sf-lug] AC adapter compatibility

Michael Paoli Michael.Paoli at cal.berkeley.edu
Tue Feb 24 18:38:50 PST 2015

If the power specifications match, including voltage, type (AC & frequency
or DC), current (it's mostly the maximums that matter on current), plug
type and polarity, with the current of the supply equal or greater than
that of the device to be powered by the supply, in general you're okay.

In the specific example you cited, the laptop apparently has a higher
current rating (3.42 A), than the proposed replacement supply (3.16 A),
so that most notably runs risk of damaging the proposed replacement
supply, so I wouldn't recommend trying that - unless you don't mind
damaging that supply.  If it's a reasonably safe supply (UL listed?),
it shouldn't overheat or burst into flames or anything like that.
The difference is "small enough" that it might manage to work, or mostly
work.  The current ratings are generally max/peak sustained draw, so,
also, ... it might appear to work, ... then fry your supply when the
laptop some later hour/day/month/year, actually draws peak current for
some reason (e.g. battery very low, CPU maxed out, memory & GPU and drive
being pounded upon, hot with fan going on high).

Best to check the actual machine (laptop) specifications (e.g. check with
Zareason, or other suitable authoritative information source).  Also, if you
have the data on the original supply, you could compare against that.
E.g. I have in my log (but this is my model, and may not at all match
Strata 6880
Rating: 19V 6.3A
Power supply:
INPUT: 100-240 V ~ 2.0A 50-60 Hz
OUTPUT: 19V 6.32A
(+ in center, - on outside of connector)
C.C.: GZ  REV.: 00
S/N: B0VW13M00XF
Also handy if one ends up in situation where folks are trying to figure
out who's supply is who's, or if someone in fact has your lost/stolen
power supply - also have the serial number (though not all power supplies
necessarily have serial numbers; can also be handy to have serial number
of your USB devices - as they may look identical to others).

You'll also note on mine, the voltage on device and power supply match,
and the current rating on the supply is >= that of the device to be powered
by it.  That's what one would expect and should have.

Having stuff logged like that is handy (easy to search and find in the text
... my system log is currently 19,524 lines long.  But can also do the
"quick and dirty" - take a digital photo, and save that (the later also
good, perhaps even better, for property protection, insurance, etc.).

> From: "Christian Einfeldt" <einfeldt at gmail.com>
> Subject: [sf-lug] AC adapter compatibility
> Date: Tue, 24 Feb 2015 18:03:16 -0800

> Hi,
> I have recently misplaced my AC adapter for my Zareason, and have found
> another adapter, and would like to ask this list if you think that it is
> okay to use the other adapter.  My computer is a Zareason UltraLap-440,
> which seems to be a re-branding of a Compal VAW70.  The sticker on the
> bottom of the machine says that it is 19 V (volts) and 3.42 A (amps).  The
> adapter says that it is 19 V and 3.16 A.  Can I safely use that adapter
> without frying my machine?
> Here is the link to the Zareason machine
> http://zareason.com/shop/UltraLap-440.html
> Here is the link to the Compal VAW70:
> http://www.asipartner.com/Solutions/Mobile/ASINotebookSolutions/CompalVAW70/tabid/1071/Default.aspx
> Here is a link to the adapter:
> http://www.pchub.com/uph/laptop/46-16927-1714/Acbel-Polytech-API-7629-AC-Adapter-Laptop.html

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