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It'll take a few days for a new adapter to arrive for one of the laptops which has the following input and output voltages

input: 100-240V ~ 1.6A 50-60hz

output: 18.5V 3.5A LPS

The other adapter has the following input and output voltages

input: 100-240V ~ 1.5A 50-60hz

output: 19V 3.42A

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Your old adapter might not have been a perfect match either. It's worth checking what voltage your notebook actually needs. This information is usually printed on the bottom. Providing a higher voltage definitely comes with risks that are hard to quantify. For what it's worth, I'd plug it into my notebook without hesitation. –  Marcks Thomas May 16 '13 at 19:45
    
@Marcks Thomas - Do you mean at the bottom of the laptop? If there is a difference between the voltages, is it still worth plugging it in? –  PeanutsMonkey May 16 '13 at 19:49
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5 Answers 5

up vote 2 down vote accepted

I would not use the other adapter. It provides too much voltage (these should be exact):

19V > 18.5V

And it doesn't provide enough current (it's alright if the adapter provides more, but not less):

3.42A < 3.5A

It's possible that it could work, depending upon how tolerant the Laptop is, but I wouldn't risk a laptop that I don't want to replace if the outputs on the adapters don't match up exactly

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Bad voltage mismatch and bad amperage mismatch each have different kinds of consequences.

With voltage, slightly underdoing it can result in performance problems, which could lead to hard drive problems (data corruption, etc.) but slightly overdoing it (no more than 10% or 20.5v total in your case) has never caused me any problems (I repair laptops and am stuck with mismatched power supplies all the time).

With amperage, even slightly overdoing it can fry components. But if your power supply is under-amped, you won't damage anything - the laptop simply won't start.

(This is my personal experience and also the "rule of thumb" taught to me by a guy who built audio receivers - he apparently learned a lot by trial and error when it came to this.)

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I agree: A slight over-Voltage (<10%) is not a problem. Over-Amperage could be damaging, but on a laptop it's usually not a big problem if the difference is less than 10%. The loader-circuit for the battery usually smooths this out. In this case the user is OK. Only the battery might re-charge a bit slower than usual. –  Tonny May 16 '13 at 20:22
    
@Kristen Jukowski - So there is no risk of frying the laptop? –  PeanutsMonkey May 16 '13 at 20:46
    
I would say with your given specs, no - you won't fry the laptop. Like @Tonny said, you're well within tolerance in either direction. And amperage is lower on the substitute supply, which is on the safe side. If anything, the laptop just won't power on. –  Kristen Jukowski May 16 '13 at 20:59
    
Also, just another thing I've found when testing supplies - there's a reason why you see Amperage specs down to two decimal places and Voltage rounded to the half-volt. I've seen actual voltage on most supplies vary to within 1-2 volts of what's listed on the supply. I've seen 18-volt supplies putting out as much as 21! Of course, as others have noted, your hardware must be tolerant of these variations, but I've found that most modern (2007+) laptops' internal power/voltage regulators are designed handle voltage fluctuations. –  Kristen Jukowski May 16 '13 at 21:12
    
The laptop will draw the current it needs, no more. The adapter's current specification merely indicates the maximum current the power supply can provide. 'Slightly overdoing it' won't fry components. Massively overdoing it is completely harmless too. –  Marcks Thomas May 16 '13 at 23:10
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It may be okay to use the other adapter just by reading the specifications you've provided alone. The lower amperage should be okay because it doesn't vary by much from the amperage from the original one.

The problem lies within the voltage regulator inside your laptop. Since those 18.5 (19) volts are being reduced to microvolts for your motherboard components, you would need to see the tolerances of your voltage regulator. I would assume that a half volt difference should be tolerable, but I'm just guessing without any solid numbers. If you're the paranoid type, or don't want to risk it, I would get the specs on the voltage regulator first.

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You need to know the AC power specifications first of both items and they need to agree for best performance

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Adapter-2: E2=19V I2=3.42A I2 in AC= 1.5A;

Adapter-1: E1=18.5V I1=3.5A I1 in AC= 1.6A;

E=Voltage; I=Amps; W=Watts;

W DC=E DC * I DC;

Adapter-2 capacity of electricity:

W2=E2*I2=19*3.42=64.98 Watt

Adapter-1 capacity of electricity:

W1=E1*I1=18.5*3.5=64.75 Watt

Deviation accuracy capacity of electricity:

(W2/W1)*100%-100%=+0,36%

Replacement should be of the same polarity, the difference in the supply voltage does not exceed 0.5V, and have sufficient capacity.

Not use 10% criteria to laptop power supplay!

In general, post it became clear that the power is almost identical ... it was possible to finish the ode Electrical and arithmetic, but we have a little torment to useful conclusions.

Deviation accuracy voltage:

(E2/E1)*100%-100%=(19/18.5)*100-100=+2,7%

Deviation accuracy DC:

(I2/I1)*100%-100%=(3,42/3,5)*100-100=-2,3%

The efficiency of conversion from AC to DC:

W1~W2; E1 AC = E2 AC;

(I2 in AC/I1 in AC)*100%-100% = (1.5/1.6)*100%-100% = -6,25%

Wow! Adapter-2 - very good!!!

Use it. Good luck!

Watch for temperature. Watch for characteristics of supply power at different CPU load as possible.

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