20v adapter on 19v laptop?

KrillBee

Golden Member
Nov 17, 2005
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I have a 20v 3.5 amp ac adapter that i want to use in a laptop that normally uses a 19v 3.16-3.3 amp adapter.

Will using it ruin my laptop?
 

Kaervak

Diamond Member
Jul 18, 2001
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I'm not an expert on this, however quite a few guys over at forum.thinkpads.com have had no problems using 72watt ac adapters on laptops that only require 56watt ac adapters. Doing the math (Voltage x Amperage), there's only an 8.3watt difference between the two. I think you'd be ok. :)
 

herm0016

Diamond Member
Feb 26, 2005
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one volt should not matter as the input voltage on the original sould have a tolerence of about 5%. wattage does not matter, as that just means that the adaptor can handle more current than the other one. wattage is voltage times amps. your computer will only draw the number of amps it needs, current is not supplied like voltage, but is taken in the amount the device needs at that moment. voltage is supplied and should be close to a constant value. make sure to check the polarity of the plug and match it to your laptop.
 

KrillBee

Golden Member
Nov 17, 2005
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Originally posted by: herm0016
one volt should not matter as the input voltage on the original sould have a tolerence of about 5%. wattage does not matter, as that just means that the adaptor can handle more current than the other one. wattage is voltage times amps. your computer will only draw the number of amps it needs, current is not supplied like voltage, but is taken in the amount the device needs at that moment. voltage is supplied and should be close to a constant value. make sure to check the polarity of the plug and match it to your laptop.

the polarity is fine,

i tried it out last night and turned it on and everything was okay.
so it appears to work, for the time being. But i've heard that over time doing this can damage a laptop. I guess it's about a 5% different, so that is kind of in range. hmm, tough call,

it would cost $20 for a new adapter, or I could keep using this one, lol. the laptop is a p3 900, decent i suppose.
 

arcas

Platinum Member
Apr 10, 2001
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If a device uses onboard voltage regulators to convert the input voltage into one or more internal voltages needed by its components then it's generally safe to exceed the input voltage by 10-15 percent. The VRMs will run a little hotter than normal since they'll dissipate the excess voltage as heat but it'll still work barring overheating.

It's the devices that do not rely on onboard VRMs that you have to be careful about.

I have an old PPC-based network computer that needed an odd 19V power supply. Closest I could find was a 22V supply. Worked fine.