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The wire on the charger that came with my laptop eventually frayed, and I had to buy a new charger for my laptop. Both the new and old chargers for my laptop plug into a standard wall outlet. On the new charger, it says the following: " Input: 100-240V ~ 1.5A 50-60Hz Output: 19V --3.42A 65W MAX. "
I assume that the V stands for voltage, and the A stands for amps. But why is there a different voltage for input and output? What is the meaning of input and output? Why is there a different amperage for input and output? Answers and Replies
phinds
I assume that the V stands for voltage, and the A stands for amps. But why is there a different voltage for input and output? What is the meaning of input and output? Why is there a different amperage for input and output?
Drakkith
The amperage is different because of the way the electronics work. To operate, your laptop needs electrical power. Power is given by the equation P=IV, or power equals current times voltage. This means that you can provide the same amount of power with different currents and voltage as long as their product is the same. Your laptop charger only takes in up to 1.5 amps, but it can supply up to 3.41 amps to the laptop at a reduced voltage. Note that the voltage required by the laptop remains the same during use, but the amount of current drawn by the laptop will change as you use it. If you're doing lots of processor/graphics intensive stuff you will draw more amps than if you just sit there at the desktop.
You can feel when the laptop draws more power by touching the transformer.
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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?
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.
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).
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
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.
did you try using your adapter to power his laptop? but in all reality it does sound like ur adaptor is failed or not making good contact with your laptops pins
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).
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
Well as long as they still have decent support(they have always been good to deal with for me), I think they will get you all fixed up. Status Not open for further replies.
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