AC adaptor seems quite hot?

I've noticed that my AC adaptor is very hot to the touch... almost too hot to hold in my hand long. Is this normal? I've heard that the newer Pavilons/Presarios are having heating issues.

 

it will get quite warm. but should still not be too hot to hold. leaving it on for days on end will heat it up to unbearably high temps and should be avoided.

how lond have you had it plugged in for?.

 

Mine gets hot as well, but nothing too serious.

And I never leave my notebook plugged in overnight. I probably could, but I just don't.

 

Generally power supplies run very warm to hot... mainly (as I understand it) because the conversion from AC to DC isn't 100% efficient, that extra power turns into heat.

When I had an adapter die, one of the most obvious signs of that it WAS the adapter was the fact it stayed room-temperature.

I suppose if the power draw on the laptop is greater than what the adapter is meant for, it could get even hotter still. Do you have a way to measure surface temps like an infrared thermometer? Hard data might make it easier to determine if its abnormally hot.

 

A side question, does anyone know how efficient notebook adaptors are ? As hot obviously means power waste. Just hope I can get 80%.

 

You will notice it gets very hot when the battery is charging and it's in full performance mode (cpu is throttled up). When the battery is removed or is already charged, and you are running on power saver mode (cpu is throttled down), the AC adapter only gets warm.

All notebook AC adapters I remember have always been too-hot-to-handle when they were under heavy load.

 

Right now, measuring with a cooking digital TroTemp gauge taped to it, it is reading 102.5F/40C and just fairly warm to the touch. It has only been on 15 minutes now. Earlier today, it was on for several hours running tasks such as Photoshop etc and was very hot to the touch. Almost couldn't hold the Adaptor. Tomorrow when I have in on again for hours I'll measure the temp again.
The 12 cell was at 100% too.

 

I think that you will find it is in the order of 95%. otherwise it would melt the plastic casing. In australia our power points are 240v, 10A thats 2400W. At 95% efficiency, that would mean 120W is turned into heat. i don't know what your power is over in the US but i assume it would be similar.

 

yeah that happens sometimes. i was in Las Vegas a few weeks ago, and sometimes it would get to hot to touch. but here where i live it only gets that hot if i leave my notebook on for a few days, which i have. the longest I've left my notebook on would be 4 days straight, so for me its normal

 

I'm pretty sure those are the maximum values, a laptop should not draw anywhere near that much power and hence should give off much less heat than that. But being a software guy, I always sucked at Electronics so maybe I'm just wrong on this one.

However, I found some details on what HP rates their bricks:
http://h18000.www1.hp.com/products/quickspecs/12433_na/12433_na.HTML

Or 83% efficiency. Compared to a Desktop Power Supply that isn't bad. Maybe it's time to break out the killawatt and see what some systems really pull....

 

That's idiotic if it's true, a poorly designed piece of crap. Any consumer product not rated for a 100% duty cycle should be clearly labeled as such.

 

Erhhh... You may want to look into the whole "electricity thing". A wall outlet will not "push" it's 10A, it will deliver exactly as much as is needed. So if your notebook asks for about 100W then it will pull about .5A from the socket. Efficiency is more likely to be around 80%, not 95. And that's a fairly efficient one already.

 

The website listed these adaptors:

HP 65W Smart AC Adapter Spares #391172-001
HP 90W Smart AC Adapter Spares #391173-001
HP 135W Smart AC Adapter Spares # 397803-001
HP 90W Smart Auto Adapter Spares #394882-001
HP 65W AC/Auto/Air Combo Smart Adapter Spares #403706-001

I have the 65W Adapter.
Would the 135W one be the most efficient and cool better maybe?
Would someone explain the W rating please?

 

W = V * A

I have a 90W brick. On the label, it says output voltage is 19.0 and Ampere's consumed is 4.77.

19.0 V x 4.77 A = 90.63 W

If you get a beefier power supply, you need to ensure three things.

1. that the output voltage is identical to your existing one. identical. if it's different by even half of a volt, you can ruin your battery and possibly also the charging circuit and your laptops internal voltage regulator. (not to mention void the warranty)

2. that the plug is the same size / type to attach to your laptop. There are many different power plug styles out there.

3. that it is capable of the same or more W as your old one. If its not, it will run even hotter and can even catch on fire if it's too under-rated.

 

nothing in electronics is 100% efficient, and anyone who thought so is idiotic. copper wires even have a resistance. and a transformer with an iron core can not have 100% efficiency due to eddy currents + losses due to magnetic flux loss in the coils. what do you know about power electronics, it doesn't seem like very much.

 

It will push 10A if the load attached has an impedence of 0 ohms. the example i gave was thoretical (what is the impedence of a transformer?) no, i do believe that a domestic transformer is more than 90% if not my stated 95%. do some reaserch if you don't believe me.

 

the battery charger on a laptop, and a desktop power supply perform entirely different functions.

you could also compare its efficiency to a washing machine or a kettle. you are comparing apples to cattapillers.

edit: sorry for tripple posting guys. i notice a comment and then reply but then don't know how to edit a post to put another quote back in.

 

Read my post again, I did not say '100% efficient', I said '100% duty cycle'. FYI- those are two very different concepts.

Here's a definition: http://en.wikipedia.org/wiki/Duty_cycle
"Duty cycle is the proportion of time during which a component, device, or system is operated. Suppose a disk drive operates for 1 second, then is shut off for 99 seconds, then is run for 1 second again, and so on. The drive runs for one out of 100 seconds, or 1/100 of the time, and its duty cycle is therefore 1/100, or 1 percent."

Therfore, if I leave my laptop powered on 24 hours a day, 7 days a week, it and its power brick are experiencing a 100% duty cycle. (This has nothing to do with efficiency).

 

Sorry my bad, need to read a bit slower.

not if the product is obviously not intended to be run at 100% duty cycle. A charger, is just that. it is not a power cord, and therefore should only be used to charge.

 

HUh? AC adapters are for charging only? And here I am thinking it was for converting power from Alternating current to Direct Current.... It isn't a power cable, its a power supply.

Sorry, but if someone leaves their laptop on 24/7 and it causes a fire from overheating, would the manafacturer be able to just avoid liability by saying it doesn't have a 24/7 duty cycle?

Asssuming a reasonably temperate environment with proper airflow and sane workload, there is no reason a laptop could not be left on 24/7. If the thermal design of the laptop or power supply won't allow for that, then frankly a recall would be in order.

 

I would imagine a decent amount of tolerance is built into these type of electronics so that a laptop specifying a 19v adapter could use 18.5v or 19.5v adapters without any issue at all. I have used AC adapters 4.5v/5.0v AC adapters interchangeably for many years.

On a side note, the HP power adapter page referenced earlier in this thread appears to indicate the laptop being able to accept different voltage levels:

 

For computer power supplies, 80%+ at both light and heavy load levels is generally considered efficient.
http://www.80plus.org/

The purpose of both desktop power supplies and laptop power supplies are to convert AC to DC power.

 

The AC adapters are for both recharging AND a power source. Period! Whoever says otherwise is WRONG!

 

Hell no. A wall outlet will "push" a lot more in a 0 Ohm load. Buring wiring if no fuse is there I might add.

I strongly suggest you take electricity 101 before tossing around statements like that. As other stated, a notebook power supply is pretty much the same as a desktop power supply in it's operating principle even though more often than not a bit more efficient. But 95 or even 90%? I don't think so.

 

Can you show me any HP literature that says this? I don't believe this is the case, particularly for a "desktop replacement" type of machine like th dv9500t. I leave mine on a desk, powered on 24/7 and have had no problems. I use an external monitor, keyboard, and mouse, I don't carry the laptop around with me.

FWIW, my laptop is only slightly warm to the touch on the underside. The power brick is the same, only very lightly warm to the touch. It's been running for about 4 days straight now, no suspend or hibernate or anything, just 4 days running.

Many laptops can be operated with no battery installed at all, only the A/C adapter. I haven't tried the dv9500t, but my old Panasonic Toughbook was like this.