Ac Adapter Voltage Output

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HassanIqbal

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Jan 25, 2014
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Hi, i have an HP AC power adapter with (on the label) 19.5V DC. checked it with a voltmeter, it was 19.78V DC. whenever i connect it to my laptop, it doesn't charge the battery or wont power up with battery removed and adapter plugged in.
Checked a second same adapter (friend's). Same rating on the label but output of 19.85V DC. and it works fine with my machine.
is there some workaround or do i buy a new adapter?
 
Solution
If it is that new, contact HP, they will send you a new one(you may need to give a credit card number so they can ensure you will send the old one back after). They did that with a notebook battery for me.

The slight variation in voltage may well just be from slightly different revisions of the power supplies internal boards/parts.

It is important to know that laptop does not run on 18.5 volts it drops it down the the voltage required with a built in regulator(a very good accurate one too). this slight difference will not cause issues for you, just get the new adapter and you should be set to go.

nukemaster

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Chances are adapter has simply failed/malfunctioned.

Testing with a volt meter has no load and some power supplies will overshoot a bit when they have low loads(it was far worse before regulated power supplies. Those things used to say 6 volts and put out 12-15 at no load, but as soon as the device they are intended for is connected it gets pull right down to 6).

When the load of a system is placed on a faulty adapter, if it is well made it will just fold over(shut down) rather than causing damage

back on topic. Please also ensure that the adapter you get has the same or greater rating for amps or watts(on the DC side).
 

HassanIqbal

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Jan 25, 2014
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yes both adapters have the same rating (OEM supplied).
i was curious regarding the differences in the output voltage at idle for both. is there any solution recommended? thanks
cuz its less than 3 months since i bought it and got really annoyed with this :??:
 

nukemaster

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If it is that new, contact HP, they will send you a new one(you may need to give a credit card number so they can ensure you will send the old one back after). They did that with a notebook battery for me.

The slight variation in voltage may well just be from slightly different revisions of the power supplies internal boards/parts.

It is important to know that laptop does not run on 18.5 volts it drops it down the the voltage required with a built in regulator(a very good accurate one too). this slight difference will not cause issues for you, just get the new adapter and you should be set to go.
 
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nukemaster

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The powering a dell is very interesting(not that my HP did not power an acer for a short while. Maybe the dell is light enough. I had a bad voltage regulator show perfect on the meter and even run some leds' but would not power any actual devices. strange the way things can fail).

Maybe you have to disconnect it and let it drain an have an inspection of the contacts to ensure they are not bent too far out. the center ones can get this way sometimes(some laptops have 2 little fingers that grab the center, see how those look).
 

HassanIqbal

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Jan 25, 2014
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10,510
thanks nukemaster, but the funny thing is there is no apparent damage at all. just got the HP message (The Smart Adapter is not functioning properly) a few times and then it totally stopped working..... just contacting HP for this
 
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