Laptop Charger Question

  Taff™ 14:29 10 Jun 2008

Just had a friend drop a laptop in for attention but they forgot the charger. It`s an IBM Thinkpad and it states on the bottom 16V 4.5 amp. I have various other chargers lying about mainly 19V and ranging from 3 to 7 amps.

What mustn`t I do? I can`t remember what the critical factors are to prevent destroying the laptop.

  chub_tor 15:00 10 Jun 2008

Firstly you should not exceed the rated voltage and you have to ensure that your chargers give smoothed DC out. Secondly you need to know the polarity of the laptop socket. If I look at the back of my Toshiba laptop there is a clear symbol showing that the centre pin is positive and the outer edge is negative. If your friend's laptop has a symbol on the back and you have the appropriate size plug and you are confident that the charger you are using will supply 4.5A at 16V DC out you should be OK. But I would urge caution on cheap chargers as their outputs are often not very smooth and they sometimes have their current rating exaggerated.

  Taff™ 15:15 10 Jun 2008

The polarity is OK and all the chargers are leading brands. How do I know if they will supply 16V at 4.5 amps though?

  chub_tor 15:22 10 Jun 2008

Unless you have some external way of loading them up and measuring the voltage at the rated current you don't know. Personally I would give it a go with a unit lower than 16V to start with - say 12 Volts, with as big a current rating as possible and switch on the laptop to see what happens. You are unlikely to damage the laptop with the lower voltage but you must get the polarity right first - check it with a meter if you can.

  woodchip 16:13 10 Jun 2008

Get the Adapter off him, You do not want to make it worse by blowing it up

  Fruit Bat /\0/\ 18:46 10 Jun 2008

DO NOT exceed the stated voltage!!! It will blow the power assembly on the motherboard.

If you try will a lower voltage the it will draw more amps also bad for the machine and probably the adaptor.

  chub_tor 20:48 10 Jun 2008

Fruit Bat /\0/\ I'm sorry to disagree with your last point but with a fixed load and a reduced voltage it is not possible for the current to increase. Ohm's Law still rules.

  Taff™ 09:18 11 Jun 2008

I think I`ll wait for the correct charger! Thanks for the input though.

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