Are Laptop Power supplies limited to their official wattage?

I got a votage multimeter/kill a watt today to see just how much power my laptop was using and whether it was using more than the 180W adaptor can provide.

I was surprised to find that I could at max make it provide 182W on the kill a watt and that was with 3.3ghz OC and 1.1V OC and an OC on the GPU.

Now what confused me was when I upped the voltage to 1.15V on the CPU and increased the GPU clocks even higher the meter didn't register any higher wattage being used.

Does this mean the adaptor strictly regulates the wattage to 180W and won't allow much if any extra charge.

As a side note I ran the OCCT PSU test with everything at stock including CPU undervolted at 1.0375V and I got a blue screen barely after it started the last wattage reading I saw was 170W then before it registered the next step up (it seems to ramp up the power usage) it crashed. I think this confirms that the power supply basically was unable to provide the power needed for the computer.

What do the good people of this forum think? I intend to upgrade to 220W if this is what is happening.

 

personally , i would go higher... a G73 can suck 150W+ under load and especially in benchmarking so PSU becomes hot... i'd personally get a 180W PSU but really , the 150W is enough... the PSU can take it but in ur case , with all the ocing , for more headroom i'd get a 220W PSU.

 

Well sean if I upgrade you can have mine . It is a universal power adaptor so I wouldn't worry about compatibility. Anyways thanks for the input

 

Don't forget that beyond the adaptor brick, there's an actual power supply circuit/board in your notebook. Maybe the limit isn't in the adaptor brick, which I've heard can generally provide more power than rated (albeit in short bursts), but with the power circuits in your notebook that won't let it draw more than 180 watts?

 

Interesting theory. Would be disappointing if that is true. Hopefully if I upgraded to 220W it would limit me to that amount too

 

It won't. If it's the internal circuitry that is limiting things, then just upgrading the power block won't help. The internal circuitry has no idea what kind of a wire is feeding it juice. It will only complain about when the voltage drops due to high current draw (adapter overloaded).

However, if it's internally limited to 180W and you gave it limitless power - it'll still draw only 180W.

Also, there is always some overhead in the design for safety reasons, as well as accounting for manufacturing inconsistency. If they calculated the component values required for 180W exactly, they'll be shipping some that can only do 170W, unless they have PERFECT quality control. So, if you connected a custom high powered resistor (don't do it...) to your adapter, you may find that it can deliver maybe 200W and still stay within the required voltage range.

 

I see what you are saying. So basically there is little point in upgrading unless the current adaptor is dropping its voltage well below the 19V required by the laptop causing a crash under heavy power draw? The 220W adaptor is 20V so it might alleviate that problem if it exists? Wish I could measure the voltage draw under heavy load to see just what voltage the adaptor is outputting at 180W+

 

What might be better is if you could find a notebook that you know draws more than 180 watts and try to use your universal in that one. That way, you could tell for sure if it's limited to 180 watts only, or if it can put out more, if only briefly. Otherwise, if you could get a 220 watt adaptor with the ability to return it, it might be worth trying. I think it's unlikely to work, unless your universal happens to be mildly defective, but if your universal had been mildly defective, I would think it would have been unlikely to be able to sustain 180 watts for long periods of time without burning out.

 

That's the thing I barely ever push it so hard. I game very rarely these days and this is the only way I would ever exceed 180W. I idle at 65W btw lol and it doesn't really exceed 70W browsing net and watching multimedia which is what I do most of the time.

So I guess it could be mildly defective as in it can't provide a stable enough 19V +1-V when asked to provide over 180W. The thing only cost £30 so I wouldn't be surprised lol. The new one I hope is better made as it costs twice as much.

Interestingly enough the original power adaptor was rated 19.5V 150W while the back of the laptop states 19V. Perhaps the engineers at asus came to conclusion that more than 19V is required?

Edit : I have bought the 220W power supply. I await eagerly to see what change it brings if any

 

The adapter is not outputting over 180 watts. The watts drawn at the wall will be higher than the watts that get to the computer, which is what PSU's are rated at, not how much they pull from the wall. The most efficient psu's are in the neighborhood of 90% efficiency under the best circumstances. So under the best case scenario, your laptop could be being fed up to 183x.9=164 watts.

No, that doesn't matter. Is your battery 19.5 volts? No. The motherboard's power circuitry will take whatever voltage it gets and bring it down to what the computer needs to operate. The value of that voltage doesn't matter as long as it is within certain reasonable bounds.

 

That is interesting Trottle I didn't realise that the number of watts drawn at the plug will be higher than used by the laptop.

The battery is rated 11.1V but it certainly doesn't last long maybe 45-60 mins with the processor running at 1ghz. I just wonder why I get blue screens running OCCT PSU or CPU burn in tests after a short time. I haven't ever had this issue running Prime 95 at 1.15V and 3.3ghz for hours. Which is certainly more power consuming than 3ghz at 1.0375V for a few seconds.

 

Sorry, I have to disagree with your statement. The rating of power supplies are based on what it can deliver to the load. In other words its already takes in to consideration the loss in efficiency and the variance on the line voltage into the power supply.

 

Do those tests work fine on battery power?

Also are you removing the battery when you do any testing for power consumption with the kill-a-watt?

 

What? The kill-a-watt is measuring power consumption between the outlet and the power supply. There is a loss of energy from one to the other side of the power supply. Therefore, the kill-a-watt measurement is naturally going to be higher than what is being output by the power supply. Also power supplies are rated at what they deliver, not what they consume. Efficiency has no bearing on that rating whatsoever.

 

Trottel,

read what I said.

I was disagreeing with your statement about the supply not delivering 180W, you were subtracting the efficiency off what the supply could deliver and that's not true.

Also I do know how the kilowatt meters work. And fully understand the supply should pull more that what it can deliver. I am a EE by profession, so I do know what I was saying.

 

Yeah, dont try feeding it 3kv

 

Oh, you misunderstood me then. He said that he recorded up to 183 watts off the kill a watt. I was saying that the power supply was delivering up to 164 watts assuming 90% efficiency. I wasn't using the rating and telling him that the power supply was only able to supply a certain amount below the rating. No wonder I didn't know what you were trying to get at.

 

If I remove the battery my lappy would fry lol. Need battery to be installed 100% of the time to complete the circuit for my fan mod. 12V hooked up to fans permanently from battery connections.

 

Humm. I wouldn't suggest you try that. When a power brick can no longer keep up its rated output voltage reading it means that the internal resistance is too great for the current flow you're trying to put through it. So getting a 20V adapter and "overload it" so it drops to 19V is not a good idea for two reasons - in the long term, the adapter may burn out, and in the short term, you might fry your laptop just because under idle conditions you might be actually giving the laptop 20V as opposed to the 19V it expects.

 

Yep, I did read it wrong, Your explanation above is much easier to follow. All it takes is a few words to throw the meaning off.

 

I have to disagree from what I have read everywhere on the web including power supply suppliers (who could be sued for giving out misleading info to customers lol) say that so long as voltage is within 10% of the voltage listed on the laptop it is safe. 20V is only 5.62% higher than 19V while the original adaptor was rated at 19.5V so only 0.5V up from that.

Either way I will take the risk. Have done it several time already with this machine and it is still working No pain no gain as they say!

 

King,

You will be fine with using a 20V supply, the circuits are designed with at least a 5% tolerance of the supply, and more likely will easily work with a 10% spec. I am very familiar with how the power input circuits work and really I would not be worried about it from a long term standpoint.

 

Unfortunately the new adaptor pretty much fried itself before I even plugged it into my laptop (thankfully). Sending it back for refund. The wire going from the adaptor literally almost became too hot to touch!! and the 4 pins on the end went black. Very scary for me

Pretty much put me off ever upgrading my power supply I don't think it was my fault I did put a tip onto the 4 pin end which is designed to slot onto the 4pin adaptor tip but that shouldn't have fried it should it?? This is what I was using on my current 180W adaptor that also uses the 4 pin tip

 

ouch... might have been faulty... did u buy a proper one from targus or something? A universal adapter would be better because u could try different tips.

 

ouch... might have been faulty... did u buy a proper one from targus or something? A universal adapter would be better because u could try different tips.

 

Unfortunately there are no proper 220V universal adaptors. However this one should have worked just the same as a universal adaptor thanks to it 4 pin tip that I have tips for already.

 

That tip even though it fit, might not have been compatible with the pin-out of the power supply and fried it. Plug your next one into the wall without connecting your part onto it first.