# Using "wrong" voltage/amp-age for laptop power

quaggydog 14:15 12 Feb 2006
Locked

Can anyone advise on the dangers (or otherwise) of using a 16V 4.5A power supply on a laptop that normally expects 18.5V 3.5A? Will it damage the hardware? Will it damage the battery?
Does anyone know where to buy replacement AC adapters for laptops cheaply?

johnnyrocker 14:25 12 Feb 2006

i doubt the battery will be damaged but more expensive components might.

johnny.

click here for Absolute batteries Laptop power supply page,if they don't list yours, try e-mailing them, they're very helpful.
As to damaging the laptop with your alternative supply, I'm unsure what exactly would happen, but considering the potential for expensive termination due to applying a higher current supply. Isn't something I'd contemplate doing.

David4637 14:32 12 Feb 2006

Check the output voltage with a meter, if it does not exceed 18.5 volts then laptop should not be damaged. Its a risk you have to decide if you try it. David

Fruit Bat /\0/\ 14:47 12 Feb 2006

You will probably find the 16v is not high enough to let the laptop run.

The laptop will not draw any more currentthan it requires

Chegs ®™ 14:47 12 Feb 2006

I've used a variety of alternative supplies on my laptop with no trouble so far.I aint to fussed if it damages it as its an ancient dinosaur of a machine that does to experiment with.If your laptop is an important device to you,dont try it as failure will be expensive.

wjrt 22:11 12 Feb 2006
Bagsey 22:33 12 Feb 2006

Current (I) = Voltage V / Resistance R Therefore if the Voltage applied is less and the resistance stays the same then the current drawn must be less. So no damage will ensue. But there may not be enough voltage to drive the computer . If the battery is left in placethen it will act as a buffer and protect the machine against fluctuating voltage.

quaggydog 23:20 12 Feb 2006

Bagsey... I was thinking along these lines myself.

But my next questions are:
a) Since the current is inversely proportional to the resistance - to what does the amperage figure on my adaptors refer?
Is it a maximum? Like a fuse? If so, I would guess that the adaptors are intended to opearte with a laptop that draws less than this maximum. (Does this make any sense?)

b) I take it that reversing the situation (using an 18.5V adaptor with a laptop that normally uses a 16V adaptor) would be more likely to cause damage to the laptop. Am I right?

Bagsey 07:38 13 Feb 2006

a. Max. the adapter can handle.
b. Yes that is correct.

Fruit Bat /\0/\ 09:44 13 Feb 2006

Over voltage will "burn out" may components in your machine.

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