# AC Adapter Problem PLEASE HELP!



## juliette salexa (Dec 22, 2008)

Hello,

I have been told that using an AC adapter for my laptop OTHER than the one that came with the laptop, is safe ONLY if the AC adapter outputs with the same voltage, amperage and polarity.

How about if the adapter has the same voltage, but a slight LESS amperage?? (I am aware that too much output current is okay, since the laptop will only draw in what it needs, but whether or not too little can cause a problem is not as apparent to me). Is this okay??


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## blackbox_ns (Nov 19, 2008)

Depends on what the laptop draws for current, as long as the power supply meets all the other requirements of the original then you just need to make sure the replacement power supply can provide more current than the laptop draws, otherwise you are just going to over tax a power supply and burn it out.


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## Done_Fishin (Oct 10, 2006)

The most important part is whether it allows the required peak output current as the laptop starts up .. if the load trips the over-current sensor it will never allow your laptop to get moving unless it draws battery current first, at some point when the battery gets lazy .. it will confuse you as to why it's not working when everything looks fine


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## DonaldG (Aug 23, 2007)

Hi Juliette :wave:

Welcome to TSF...

You are correct about the computer drawing what it needs in current (amperage). 

Only try the following if you are absolutely sure that the voltage and the polarity is the same as the original unit.

As long as it is only SLIGHTLY less in amperage, it *might* be OK. BUT do the following check from time to time, starting as soon as possible:

With the battery removed, run the computer for some time, feeling the temperature of the ac adaptor every 5 minutes or so. It will get warm. If it is only warm, then it is not under too much stress. If you can run the computer on just the AC adaptor for say over an hour without the adaptor getting overly hot; OK so far... It is overly hot if you cannot bare to touch it for an extended period.

Then put in a flat battery and run the computer at the same time it is charging the battery. Make sure that you are using the computer on some intensive task such as a game or photo editing. This is when the computer will be wanting to draw maximum current. Carefully monitor the temperature of the adaptor every 5 minutes. If it it is very hot to the point it becomes uncomfortable to hold for 60 seconds or so, then it is NOT OK. On that other hand, if it is hot but you can still comfortably hold it for some time, then it should be OK.

Another piece of advice: always make sure that there is nothing covering the ac adaptor. It needs to get rid of the heat it makes. If it is covered it could overheat and cause a fire at worst or burn itself out.

Regards
Donald

EDIT: As I was typing my reply, Done_fishin posted a very important point that I had missed. :wave:


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## Done_Fishin (Oct 10, 2006)

DonaldG said:


> Another piece of advice: always make sure that there is nothing covering the ac adaptor. It needs to get rid of the heat it makes. If it is covered it could overheat and cause a fire at worst or burn itself out.


Starnge you should say that since for some time now I have a habit of placing a small 12V fan blowing air over the cases of my power adapters (none for laptop, I should mention) just to keep them cooler .. it seems that modern technology has forgotten all about heat dissipation which used to happen via small holes or vents in the bodies of the supplies or casings .. so I help most of my overheating appliances with a fan driven by a USB adapters external power supply


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