if you know a bit about electricity, please help

I am having a bit of a problem with my laptop. My AC adapter broke, and I got a universal one.. I can set the voltage from 12 to 24, and my laptop's input voltage is 19.5, so I set the adapter to 19, cause it doesn't have 19.5, however, it doesn't seem to be charging properly.. should I/can I set it to 20, or will it damage my computer?

 

I'm no expert, but I think the voltage should match or else it could damage the computer

Maybe .5 is close enough, but I don't know

 

what are the amperage settings? it should be in milliamps... mA

I have this issue with a lot of my music gear and a lot of time it's the mA draw that messes with it and not the voltage... although computers might be more picky. be careful you don't want to blow your battery up.

 

I think it's 3.34.. it says "input 19.5V=3.34A" on the laptop and on the adapter it says "19V=4.5A MAX -20V=4.5A MAX"

I don't understand

 

btw does anyone know what polarity means? I was on Yahoo Answers asking the same question and someone told me something about the polarity.. no idea..

 

ok yeah that makes sense that a computer would draw more. that like how much electricity is coming through... I think... it's been a while. and voltage is like how fast. kind of like a pipe with water. Amps is like the size of the pipe with water in it. Voltage is how fast it moves through or something.

your amp output might be too high on your adapter. it's running an amp over what your computer draws. you might try looking at your computer's tech pages or seeing if they have somebody on their chat lines. googling it might help too.

and it says 4.5amp max so maybe it doesn't always draw that much current. sorry you've reached the edge of my knowledge.

 

yeah polarity is positive negative. if it's not polarized right then you're sending a positive to a negative and it won't flow. most adapters won't let you polarize incorrectly. but if you can there's usually a white stripe on the positive side... or maybe even a little + sign. but that's in the us I'm not sure if inernational electronics get different. over here (us) we also have a big plug and a little plug so you don't incorrectly put the plug in against polarity.

 

Make sure the polarity is set properly.

I don't think 20V would hurt. The voltage from the adapter drops as the current drawn from it goes up. You may have to boost the voltage up slightly from 19V. You're drawing 3.34 A from an adapter that is rated at 4.5 A which is getting close to what the adapter can supply, so it's voltage under load may have dropped below the 19V that the selector says.

The current rating of the adapter being 4.5 A won't hurt a device that runs on 3.34 A. If anything would hurt, it would be to use far too high a voltage or a voltage of the wrong polarity.

.

 

phew! this is complicated.. but I think I understand and am sure the polarity is set right - definitely.. so far it's been alright.. the only thing I noticed on 20V was that the adapter like whistles a bit once in a while.. I hope that's not a bad thing!

 

pen, you need a good basic textbook

your universal adapter PROBABLY won't do it simply because some laptops require VERY specific inversion, that said, most laptop power supplies are expensive filtered jobs, and though you might be able to hack something together you might be better off asking someone who knows more about EE, or going with the corporate evil edition, which I know is going to cost entirely too much

I'd say breadboard something, but, that's an EE intensive solution.

 

Simple as this.. Dont use anything but the recommended POWER PACK.
Dont interchange this or use a universal adapter.
They dont supply a steady current since they are adjustable.. measurements in milliamps are very precise to this equipment. While you may get a power and charge.
It will be improper and cause long term harm. And possible a fire or battery explosion.

Use only the Product rated for the laptop battery.. If you violate this by using just anything, You have endangered yourself and others. And in many cases invalidate a warranty.

 

since laptops have such off the shelf parts, you might want to research what the power supply IS, and what kind of battery you have, and then look for another company selling it for less too.

 

well this AC adapter says its officially compatible with my laptop though.. and many others, mine included..

 

it just so happens i'm a electrical student studying to be an electrician, i have not however began my studies of AC characteristics that's only next semester. However I can tell you that you can use the 20 Volt input and it will chrage better then on 19 volt input. The only problem is that as fellow posters mentioned consumer electronics often times need currents as small and precise as milliamps to operate safely. increasing the voltage will increase and throw off these tiny currents throughout the laptop. The result of overcurrent will be be overheating.

Unfortunatly without in depth knowledge of AC, and without the ability to measure the operating currents inside your laptop, it would be my advice to stick witht he recommended 19.5 V for your safety. Or B. Go to a local guru to take measurments of the currents inside your laptop to tell you if you're in danger of over heating.

 

take it to an electronics store, explain your quandry, see if they can help. theyll probbaly charge you some cash for it, but i rather imagine a working laptop is worht it.

that said, i typically use the manufacturers parts because they are actually designed to work with that particular piece of hardware, and are -significantly- more reliable

 

it's just really complicated cause I'm in Spain right now and my laptop is exclusively American.. last time I took it to a repair shop they told me they couldn't do anything cause that Dell was never exported to Europe :/

 

!? Yah ... but how complicated would it be for them to stick an Ammeter to it to measure the amperage going into you PSU. They sound like a lazy lot to me... :S

 

they are extremely lazy.

 

Based on the specs you provided your power supply should work. When a device is specified to draw 3.4 ma you need a power supply that will provide that or more. The supply isn't pumping out 4.5 ma it is just able the handle that kind of draw. In most cases a power supply is generally rated 30% more than the current draw of the device it is powering.

DC batteries are generally charged at what is called a float voltage. A 12 VDC car battery is charged at close to 14 volts. If you charge it at 12 VDC it never gets fully charged. I would bump the power supply to 20 volts and see what the battery does.

If the power supply is working as it is specified you may have a bad battery. Dell did a major battery recall in the recent past.

 

They would need to check the amperage from the PSU to the PC. To measure the AC input amperage can be misleading as there is usually a 25% efficiency loss in the conversion from AC to DC.