Archived from groups: comp.sys.laptops,alt.comp.hardware.pc-homebuilt (
More info?)
You have some nice speculation/theories there.
Your power supply tolerance figure of 5% to 10% sounds slack to me.
Have you ever seen the input power specifications for the laptop
computer in question? Have you ever even seen any input power
specifications for a laptop computer?
When I experiment with something, I consider the replacement cost. A
laptop computer cost a lot of money. I suspect the input circuit
would reject an inadequate supply, but I've never seen that
information from the engineers who know.
There is nothing ambiguous about a correct power supply. In a
competitive market, a manufacturer cuts costs. Since higher current
output power supplies cost more money, a manufacturer is not going to
include a significantly greater power supply than what is necessary
for the device it is intended to run. There might be exceptions.
If I were you, I would demand more information. Have you ever
measured current while using the correct power supply? If not, and if
you have never seen the specifications, I would say your practices
are a little bit reckless.
Barry Watzman <WatzmanNOSPAM@neo.rr.com> wrote:
>As a general guideline, your comments are correct. However, for
>day-to-day use, they probably overly conservative.
>
>First, the voltage tolerance is at least 5% and may be 10%. At 19.4
>volts, that 1 to 2 full volts (approximately), so using a 20 volt
supply
>with a laptop designed for 19.4 volts is unlikely to cause a
problem.
>
>Second, the current requirement of the laptop is equal to or less
than
>the current output of the "correct" supply. But that current is a
>MAXIMUM -- presume, for example, charging a fully discharged battery
>while using 2 PC Cards and drawing 500ma from each USB port, while
>burning a CD with an auxilliary keyboard and mouse plugged in and
>running a highly CPU intensive application that draws maximum power.
>
>It's unlikely that a user would actuall do all of that, so a power
>supply with a capacity lower than that of the "correct" power supply
>will likely run the machine in "normal" operation just fine. I run
lots
>of laptops from generic supplies with half the capacity of the OEM
supply.
>
>Finally, while it may not work, it's unlikely to do hardware damage,
and
>if it does, it's more likely to be to the power supply than to the
computer.
>
>But, there is indeed some risk -- however small -- and you have to
be
>willing to take that.
>
>Also, all of this applies only to power supplies with simple "2-
wire"
>interconnects to the computer. If the power supply has a multi-pin
>connector, then it's more than just a power supply (often part of
the
>charging circuit is in the "Power Supply"), and then you definitely
>should use a correct OEM supply.
>
>
>John Doe wrote:
>> Lordy <spam_box@gmx.net> wrote:
....
I'm not sure what the amp ratings were but I suspect you'd be 
/www.claudelyons.co.uk/energy_saving.htm
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