HP8740w power supplier question...

Hi All,

Just received my 8740w (WD941EA), very pleased. However I was amazed at the size and weight of the power supply. It is 19.5cm x 9.5cm x 4cm. Why is it so large. It still seems to charge the same size of battery as in my old HP nx8220 and its power supply is 1/3 size or not smaller. The weight is 1.2kg ! The number's are Rev:A01 0400676401 and on the bar code CT:WBGUC0ALLYW18D. It also has 230w on it. The socket is of the UK kettle kind, ie 3 wide prongs.

1) Why so large?

2) Is it possible to get smaller ones?

Thanks,

Sam

 

It is so large because your machine may need the power

Be happy to have the 230w one because a few have problems with the 200w, which I think is physically not smaller at all, and the power hungry processors and graphic cards. Also you can use it easier with an advanced docking station, too.

I don't think there are smaller ones and would not try any third party psu because you can damage your 8740w.

 

Sotton, thanks for your reply. However I am a little confused by it. I have since looked at HP's site and found multiple power adaptor that appear compatible with the 8740w.

see: HP EliteBook 8740w Mobile Workstation - Accessories, supplies & services

They are listed as compatible for the 8740w from 65w to 230w adapters.

So it seems that I can get a smaller one???

Sam

P.s BTW I am happy

 

the problem is that there are different 8740w configurations

if you have the FX5000 and the 940XM you need for sure the 230w if you want to use all the power

if you have the M7820 and the 560M you may be need only the 150w psu

and if you just use 2D graphics (browsing, office) you may be able to need even less.

so, you need some (good) device to measure the actual watts needed and be maybe able to use the 65w for your tasks...

Hopefully there is a safety feature but at least the machine switches off if there are not enough watts available

 

I think SISoftware Sandra may provide the relevant values. I have it on my XP/nx8220 which is indicating a CPU wattage used of 25W. So I will run this on my 8740w and see what I get.

So if my requirement is say 50w then I get use a smaller PSU. What happens if I try to use a smaller psw ie 65w when occasionally my required wattage goes to say 75w? Will some components scale back or will damage occur?

HP do not state on their site that support is dependent on configuration although I understand the logic.

Sam

 

the problem is that there are different 8740w configurations

if you have the FX5000 and the 940XM you need for sure the 230w if you want to use all the power

if you have the M7820 and the 560M you may be need only the 150w psu

and if you just use 2D graphics (browsing, office) you may be able to need even less.

so, you need some (good) device to measure the actual watts needed and be maybe able to use the 65w for your tasks...

I wonder if this safest feature exists? It would be excellent if it did.

 

It could be that with a low power psu like the 65w AX727UT you are able to run the laptop like if it is on battery and maybe are able to even charge the battery, this would make sense too

so: full power with the big one and battery power with the smallest one

 

sam, just be lucky you got one lol. i had to buy one for my wd941EA, so don't look a gift horse in the mouth. you will need it when you upgrade later on.

if you really wanna buy another one, it'll be about 45 quid. DONT get the 65W one because the 2800M trips it when you are watching youtube.

you could probably get away with the 180W psu, IF you can find a reseller still selling them in the UK. (or i could mail you one from here possibly)

i have been very stable on 230w since i changed my PSU. its a bit heavy aye, but man my girl is happier with it!

 

Siorah, Hi there. Yes the 8740w has finally arrived and very happy

Regarding the PSU if I can get away with taking a lighter one with me when I am visiting customers then that would help. I do not anticipate to be working the 8740w hard onsite with customers so I could see how I could get away with a less powerful one. I guess I need to measure what wattage I need. At the momenet my best idea of a utility is SIS Sandra... other ideas?

With regard to alternatives, well there seems to be a whole list on the HP page. I guess I would go for a 90w one, 65 seems a bit small, subject to finding out my power needs.

Happy and lucky Sam

 

90 is ok as long as you are not doing anything GPU based.

if you have the 2800M like me, you will trip anything under 100W because of the gpu eh.

it's annoying to have such a power hungry monster under the hood, but i've seen the 150w/180w used ok

i don't have the part no for the 150w though.

90w doesn't even get past the boot screen on my girl.

 

90 is ok as long as you are not doing anything GPU based.

When you say "Trip", do you mean that the house circuit trips or what?

It will be interesting to see what wattage my laptop uses although it is the 941 with the 2800M. I will run sandra on it to see what it shows...

No probs

I can understand why with all of your components Does it run with the battery since it is rated at 73Wh? Logic says no.

 

trip - laptop switches to battery, or switches off/wont turn on

and yes, my machine boots to battery fine with all the kit in it, though i don't do it often!

you have the same machine as i do mate. so we are the same bar my upgrades.

 

OK, thanks.....

"Trips", good to know it has a safety mechanism.

"my machine boots to battery fine" - With 73Wh on the battery then how does this work? Forgive my slight ignorance on Wh etc. I would assume if you are drawing 150w, then I guess the battery will last no longer than 30mins, is that correct? How does the Wh business work with batteries?

"Same machine" .... Yup although not same usage I suspect. With your 3ding I guess you have steam coming out of yours !! It would be interesting to find an accurate way to measure Watts used.

As you know the Max power values are 45W for the 720QM CPU and 75W for the 2800M, but the actual usage I guess is lower if just browsing etc....

Thanks again,

Sam

 

I have just measured my usage using HP's Power Assistant on just battery and it is showing 33W. OK I am doing nothing on the laptop, but it is interesting if accurate.

I guess my answer to this especially as I am not a heavy graphics user will be to get a 90W adapter and have the battery plugged in all the time in case the adaptor trips out. But I have a strong feeling that my usage will not be big enough. Need to monitor it accurately to see.

Also may need to get a more accurate "usage monitor" if HP's is not accurate enough.

Sam

 

hp's wattage isn't far out tbh. but what you need to look for is the 'spikes' windows doesn't have good power saving features. you'll see what i mean if you have it open and play a youtube video. mine spikes to 133w then goes back down to about 85w.

 

Siorah, Thanks for this really appreciated.

It is so new that I have not setup the tinternet on it yet !! lol..... back soon.

Sam

 

I have my Kill-a-watt hooked up to my 8740w; here's a few power measurements (DC2 screen, i5-560M CPU, ATI M7820, single hard drive):

Idle, max screen brightness: 49W

3DMark06 GPU test 2: 111W

wPrime 1024M test (full CPU load): 75W

So you will definitely not be able to run it off of a 65W or even a 90W PSU efficiently, at least not under load. As noted, if your laptop draws more power than the PSU can provide, it will trip and switch to battery.

Those are TDP numbers, not power consumption. TDP = Thermal Design Power; it is a number provided by chip manufacturers to system builders to tell them how much thermal energy the heatsink they pair with the chip must dissipate in order to keep the chip within its operating levels.

 

I was able to play Civilization V without any issues using a 120w power supply with my 8740w. My config has a i7 720QM quad-core and Firepro M7820.

 

you don't have a 80w drawing 2800M mate this is my issues.

I can't boot windows on a 90w

i can just on a 120w with my kit.

but you have to run the laptop in powersave mode, so the graphics card doesn't clock up to 600/1000 memory. when it does that, it uses 70w on it's own regardless of what it's doing. i was mentioning the 'spikes' the 2800M does. the firepro uses much less power.

 

Hi Folks,

Apparently I need to provide the correct ampage as well. It looks like the power adaptor choice has been reduced on the UK site, but still large on the US HP site. When I tried to get a compatible product to ED495UT, the potential supplier was nervous about the output current. This product has the following quote:

"<11A, Over voltage protection- 29V max automatic shutdown"

whereas the compatible product was 4.7A I think. Not sure what <11A means?

Cheers,

Sam

 

4.7A seems to be too little, my 8730w PSU has 7.9A (150w) and the 180w for the docking station 19V 9.5A, I guess the higher the better but maybe also under 11A? For the 8740w even higher values could be, at least the 230w

We need an expert...

 

My 8740W 200W PSU is 10.3A, 19.5V.

I know we have an expert on electrical stuff around here somewhere . . .

 

Hi All,

After more research the all important output voltage is 19.5V and the ampage is 11.0 amps. Basically I took this from my 230w adaptor label However this assumes that all 230w is used since:

amps = watts/volts

In my case a maximum of 110 watts is used including charging of battery. I have actually found a much smaller 120w adaptor.

This is product is where I am at present:

AC Adapter/Laptop Power Supply 120W - PowerStar Laptop Pro

I am going to monitor the power usage. I believe battery charging always take about 60w although I am not totally sure since I thought that if less wattage was available then the battery would take less ie 30W and take longer to charge, but apparently the batter need a minimum amount and if not available will flip the adaptor out.

Finally I am wondering about the accuracy of the HP Power Assistant. I wonder if there is a Hardware tool to measure watts being used from the capable, ie the actual amount???

Sam

P.s I researching this abit as I really do not want to take the 1Kg 230 w adaptor around with me all the time, especially as I am not a 3d rendering power user!!

 

hi sam, there is a smaller 180w psu, but i'll see if i can find the part number.

that one weighs about 400g.

it's not specifically for our computers, but it works nonetheless.

 

I have the Kill-A-Watt device Indrek mentioned. The HP Power Assistant is fairly accurate at idle, though it doesn't update as often as I like. The Kill-A-Watt updates instantly. Idle on my machine (with one hard drive) is about 48W. I'll do some more measurements later today.

 

My system idles @ 40-44W - brightness 100nits, 840QM + M7820 + 1 HDD.

 

Hi Folks,

Really interesting comments, particularly about measuring wattage accurately. I will get my hands on one of these. From what I can tell I should allow for 20W for the wattmeter and probably similar for the charger ????

Also what is your view on being able to use a 19v adaptor instead of a 19.5v one. The supplier 230w one is 19.5V and I have read that you should match the output voltage. However I cannot find a 19.5V 180W adaptor, but can for 19V? Is there a tolerance? Also I read that this is only relevant for battery charging???

Still very interested in any part number for 180w units, particularly if they are as light as 400g. Would solve my problem.

Thanks to all,

Sam

 

hiya sam.

the adaptor i mentioned before for 400g is no longer available to get - this one is the replacement.

it's 200g lighter than the 230w, and is certfied to be compatible with the 8740w (i also have one of these)

HP 180W Smart AC Adapter (AK875AA) specifications - HP Home & Home Office products

its easier to link it than to give you the part number. this one you can buy directly, or find a reseller to see if it's cheaper eh.


if you click the 'compatible' products you will see our notebook listed.

*source - link above*

Sio

 

Hi,

I have found an alternative universal adaptor which is switchable to 19.5v with a max of 146w at 670g which I guess would operate at 7.5A. Since my analysis to date has shown the about 115w is used to charge including my other laptop processes then there is useful leeway here. 120W is a little too close IMHO.

It is available from my local Maplins store !!!

High Power MultiVoltage Universal Laptop Power Supply Free Delivery : Laptop Power Supplies : Maplin

The only question is whether there is a 19.5V J Tip socket for the 8740W which I have raised a question on.

Sam

 

Hi All,

Just got a Wattmeter and have done some measurements. Basically they tend to be around 10-15W more than what the HP meter indicates. I also assume that the charger takes some power??? So with 7 youtube windows going I am only using about 120W with charging. When upto 95% charged the wattage goes right down to 55w(HP meter) and 65W(Socket)

I thought I had found the perfect adaptor with the Maplin device, but on visiting the store I was told that the HP tips were not provided. Apparently HP can be picky on who they authorise use of their fittings. Trust is one such supplier, but their device only goes up to 120W.

So I am a little stuck at the moment, but I have not given up !! A universal device with the HP tip will be the answer, but where from?

So searching on.....

Sam

 

Not sure if this is relevant to your system configuration, but I have an i7 820/ATI M7820/DC2 which came with the 200w power supply. The HP power assistant shows it idles around 50-60W, maybe 60-90W under light load and up to around 100-150W under heavy load. I was using a 120W HP supply from an older elitebook as an additional/transportable supply. That seemed to work ok, but I got warnings from the power assistant that I should upgrade to a higher-power smart adapter for full performance.

I went ahead and got a 150W supply from HP (it's significantly smaller and lighter than the 180W supply) and I still get the same warnings but it seems to be doing just fine with my configuration.

 

About going to a smaller power supply -- when I used to build desktops, I always used a power supply that provided a lot more power than I knew the system would draw.
The power supply's efficiency is different depending on the load. If you have a 150W adapter and it's operating at 50% load most of the time, it might not be as power efficient as a 200W adapter operating at 37.5% load (assuming the system's typical power draw is 75W). Ideally you want the typical power draw to be equal to where the power supply is most efficient.

Here's a review for a desktop power supply (a very good one from a few years ago -- Corsair HX 620W):
Corsair HX520W & HX620W Modular power supplies | silentpcreview.com
See the graph at the bottom of the page; the efficiency changes depending on the load. This review of the same power supply is another example:
Corsair HX620W Power Supply Review | Hardware Secrets
Keep in mind that is a very good power supply; other power supplies might have a much differently-shaped graph (sharper curve).

I'd stick with the power adapters HP recommends for the notebook. Mine came with a 200W version and I have the i5 dual-core, DC2 screen, and M7820 ATI graphics.

 

Thanks all...

I think what I am looking for does not exist ie

150 -180W adaptor
19.5V
HP 8740W pin
~600 g in weight

The nearest is what HP is currently offering ie 980g for the 180W adaptor. Not sure is this is worth purchasing? Perhaps a new adaptor may come out that is lighter????

BTW, I have come across an interesting company called Innergie, but their adaptors are not powerful enough.

Will keep a watchful eye me thinks.


Sam

 

Does the 8540w have the same size of power plug/tip as the 8740w?

Thanks,

Sam

 

ok sam.

after some REAL digging around.

I've found a part you can use with the 8740w.

HOWEVER. you CANNOT charge the battery for too long on it.

the part number you are looking for - for the 150w HP powersuppy is:

AL192AA/613156-001

this weighs in @ 700g.

source:

http://h18000.www1.hp.com/products/quickspecs/11881_na/11881_na.html

this page has every main PSU HP make in one nice comparision chart.

hope this finally settles this issue.

The 150w is 44 quid to buy direct from HP UK.

I'm not searching anymore!

lol.

hope this helps.

http://cgi.ebay.com/NEW-Genuine-HP-...=Laptop_Adapters_Chargers&hash=item483de63a18

ebay link for what it looks like.

 

Yes. But do we really believe from those specs that

p.s By the way, where the heck is the 200W power supply anyway??

 

i did wonder that.

seems it's being phased out possibly.

that document was dated on sept 2010 so it's quite recent.

the 8700 series can run on 90w. if you have nothing powerful in it.

but in sam's case he needs <150w at least.

 

Folks,

I really appreciate the research. My charging and usage peaked at 152W yesterday off the plug wattmeter, but this would have been a transitory blip since the continuous usage was from 90 - 115W on charge. Also there is a difference of between 10 and 15w which I believe is what the adaptor uses so the laptop proabably topped out at 140W. So 150W should be fine although 180W would be safe.

Also I think when using a universal adaptor protection is vital and some sort of automatic reset is ideal. I have found these 150W usages to be very temporary, so flipping over to battery when exceeding would be good and then back again when back down to say 110W.

I will check these tables. Thanks for the graft Siorah.... really appreciated, virtual feret beer coming your way !!!

Sam

 

Sadly I do not think the 150w is compatible since it is a 19v unit.

"The HP 150W Smart AC Adapter (AL192AA) is compatible with the HP EliteBook 8730w Mobile Workstation" .... not 8740w.

So actually at the moment the nearest solution is the HP 180w unit which is smaller. I will need to think on this. At the end of the day 150w units and over are not going to be small !!

Thanks,

Sam

 

The key problem is the charging of the battery. Yes I can happily run on 65W on battery, but once I start charging the battery I need an extra 50 - 60 W. I had hoped that the battery could just charge more slowly and take less Watts, but it does not work that way. It needs a minimum otherwise the battery will not charge.... well that is my understanding at any rate.... oh for it to be wrong !!!

 

No that is not the Key problem.
I have the Nvidia card, quad core and it will not even start on a 90W. 150 minimum.
My 8540w also had the quad processor so i think the Video card is what is eating up the power.

 

dude.

the battery runs the laptop off 14v.

the 150w @ 19v will work fine. as i said you just need to make sure your battery is charged before you use it.

I have tried this very same psu in my 8740w.

with full battery, no issues at all.

charging battery = no dice.

but you can ring HP. it is compatible with the 8540w so i can't see an issue mate.

it's the lightest option you have really.

but to be honest, i just carry my 230w with me. i'm a big strong man after all!

lol

 

dude.

the battery runs the laptop off 14v.

the 150w @ 19v will work fine. as i said you just need to make sure your battery is charged before you use it.

I have tried this very same psu in my 8740w.

with full battery, no issues at all.

charging battery = no dice.

but you can ring HP. it is compatible with the 8540w so i can't see an issue mate.

it's the lightest option you have really.

Ah that is the real answer then ....

Yes I agree that charging the battery can flip over the 150W mark, although on my machine it typically run around 120W. I think the 180W one sounds the practical answer at the moment, but then again I could exercise my biceps with the 230W one until a lighter one comes onto the market

Cheers,

Sam