65W versus 90W AC power adapters

Message

JPH · #1 Post by **JPH** » Sun Aug 31, 2008 12:36 pm

I have now changed all the laptops in my office to ThinkPad T61's (falling T61 prices made it possible!) and I notice that several of the lesser models (X3100-equipped models) came with a smaller and lighter 65W adapter.

I was wondering if it is perfectly OK to use the 65W adapters with T61's which have nVidia video cards, bluetooth as well as those I have upgraded with 7200 rpm HDD (some of them even have an extra ultrabay HDD). In addition, would it be safe to use 1 or 2 USB ports with these adapters? The higher-spec machines that came with the 90W adapters also have CPU's that range from T7250 to T9300.

What is your experience with the 65W adapters?

DarkScythe · #2 Post by **DarkScythe** » Sun Aug 31, 2008 12:42 pm

I also have a 65W AC adapter with my used T60.
According to IBM, this machine originally came with a 90W AC adapter, since it uses a discrete graphics card - the 65W normally ships with units that run integrated, as far as I understand it.

I called IBM up about this and the representative assured me that there was absolutely no problem using them in place of each other, the only difference was that the 65W AC adapter would charge the battery slower. I'm not entirely sure I buy into that, but I've been using my laptop successfully with it.

awolfe63 · #3 Post by **awolfe63** » Sun Aug 31, 2008 1:24 pm

I have always been a conservative about this. In general, using an underpowered adapter can be a fire hazard. But in this case - I think it is a non-issue.

1) I can't push my W500 over 50W power consumption and that requires running games. In anything resembling office use - I can't push it over 40W. That would make the 65W adapter "safe" to use.

2) These machines can identify which adapter is plugged - so the battery charging circuit will not overdraw a 65W adapter.

3) An extra HD is only about 2.5W (*). Each USB is limited to 2.5W. - so an extra 5-7W is probably OK as well.

For <$50, I would be somewhat reluctant to take any chances - but it looks like in this particular case, there are safety checks in place to make it OK to use a 65W adapter. I am using a third-party 90W adapter from ebay that I bought for $20 and it works great.

(*) footnote - a spinning-up drive can draw up to 5.5W but this almost never happens when the GPU is in full 3D action so it does not contribute to the peak power draw.

shepseskaf · #4 Post by **shepseskaf** » Sun Aug 31, 2008 10:45 pm

awolfe63 wrote:I have always been a conservative about this. In general, using an underpowered adapter can be a fire hazard. But in this case - I think it is a non-issue.

1) I can't push my W500 over 50W power consumption and that requires running games. In anything resembling office use - I can't push it over 40W. That would make the 65W adapter "safe" to use.

2) These machines can identify which adapter is plugged - so the battery charging circuit will not overdraw a 65W adapter.

So, given what you've said, is there any advantage at all in buying a 65W adapter? Does an individual TP consume just as much 'juice' as it needs, or would a 65W plug save more energy than a 90W?

Also, how does a laptop compare in energy use to an average flatscreen TV?

dr_st · #5 Post by **dr_st** » Mon Sep 01, 2008 5:20 am

The laptop consumes as much juice as it needs. The only advantage of buying the 65W adapter is that it is slightly smaller and lighter.

awolfe63 · #6 Post by **awolfe63** » Mon Sep 01, 2008 4:21 pm

shepseskaf wrote:
awolfe63 wrote:I have always been a conservative about this. In general, using an underpowered adapter can be a fire hazard. But in this case - I think it is a non-issue.

1) I can't push my W500 over 50W power consumption and that requires running games. In anything resembling office use - I can't push it over 40W. That would make the 65W adapter "safe" to use.

2) These machines can identify which adapter is plugged - so the battery charging circuit will not overdraw a 65W adapter.
So, given what you've said, is there any advantage at all in buying a 65W adapter? Does an individual TP consume just as much 'juice' as it needs, or would a 65W plug save more energy than a 90W?

Also, how does a laptop compare in energy use to an average flatscreen TV?

Depends what you consider average - I have a 65" LCD

A 50" Plasma is 600-700W. A 40" LCD is 200-250W. A "typical" thinkpad - reading email or searching the web is under 30W.

JPH · #7 Post by **JPH** » Tue Sep 02, 2008 5:50 pm

So basically am I right in assuming that the 65W should be able to give enough juice no matter which T61 it is powering, esp one which has all of these:
* nVidia
* ultrabay HDD
* all 3 USB ports used
* Merom 65nm CPU's?

awolfe63 · #8 Post by **awolfe63** » Tue Sep 02, 2008 6:37 pm

I think so - especially if you are not doing hard-core 3D gaming. Run your setup on battery (with everything at full speed) and see what the power draw is. I'm betting no more than 45W.

shepseskaf · #9 Post by **shepseskaf** » Wed Sep 03, 2008 9:29 pm

awolfe63 wrote:Depends what you consider average - I have a 65" LCD

Consumerism lives!! Thanks for the reply. I suppose I could have been more specific about what I defined as "average", but it would certainly be less than 65".

Mr-Pacman · #10 Post by **Mr-Pacman** » Thu Sep 04, 2008 8:55 pm

How can you tell how much power is being used?

Is there something in the control panel or do you need 3rd party software?

I'm using Windows XP Pro.

I have a T61 with the discrete graphics card. I also have an extra 65w adapter from my work X61.....so I would love to be able to use that when traveling as it fits in my laptop bag where the 90w is a bit too big.

Thanks
James

awolfe63 wrote:I think so - especially if you are not doing hard-core 3D gaming. Run your setup on battery (with everything at full speed) and see what the power draw is. I'm betting no more than 45W.

awolfe63 · #11 Post by **awolfe63** » Thu Sep 04, 2008 9:23 pm

Unplug the computer.

You can then see the power draw in Power Manager. I use MOBmeter though because it produces a graph.

Mr-Pacman · #12 Post by **Mr-Pacman** » Thu Sep 04, 2008 9:37 pm

Thanks....even when playing a video game, I can't get it over 40w and that's also with music streaming via the internet, and all 3 usb ports being used.

James

EvilH · #13 Post by **EvilH** » Sat Sep 06, 2008 12:38 pm

You can also monitor power usage at the plug with a kill-a-watt. Picked one up at Fry's the other day for $20 and have been going around with it for the past week finding how much juice all vampire devices actually eat. Really quite fun and educational

awolfe63 · #14 Post by **awolfe63** » Sat Sep 06, 2008 1:31 pm

That's true. I have used one of those as well. Remember thought that the power supply is rated for 65W output - a higher input power level (at least 150W according to the markings on the unit ) is probably OK.

LIVE4SPD · #15 Post by **LIVE4SPD** » Wed Sep 17, 2008 3:33 pm

I've used my T61 (in sig below) for over a year now with a 65 watt adapter. It's fine. Sure when playing Call of Duty for an hour our two it's pretty toasty but the 90w is just as warm.

The biggest difference that someone else said above is the 65W charges pretty slow.

phr · #16 Post by **phr** » Thu Sep 25, 2008 6:25 am

The t61 apparently runs faster on the 90w adapter, if you have the battery removed. When you do cpu-intensive work with the 65w adapter, the computer uses some power from the battery and some from the adapter, and if the battery is absent the computer slows down. This is based on comments from another thread and I just checked it by experiment. My T61 (T9300 cpu, Intel graphics) came with the 65w adapter and I do usually run with the battery removed, in order to extend the battery life since I use the machine as a desktop workstation. So I think I will buy the 90w adapter.

Radioguy · #17 Post by **Radioguy** » Thu Sep 25, 2008 8:50 am

I know there's a consensus on the varying quality of the different brand keyboards used on the T series, but is there the same for the different adapter manufacturers?

http://www-307.ibm.com/pc/support/site. ... MIGR-69652

Looking at that list, Lite-On is the only brand I know, but that doesn't mean much. Does anyone know if any of them run cooler than others, or put out a more constant voltage/amperage?

Also, the plug to the laptop is the same, so is there any benefit to choosing a 3-pin grounded model? I mean, does the grounding protect the adapter or the laptop? (I'd use a surge protector in either case)

Radioguy · #18 Post by **Radioguy** » Fri Sep 26, 2008 7:51 pm

It's not aftermarket, is it?

If not, what's the current list of Lenovo-branded ones, and which is best?

awolfe63 · #19 Post by **awolfe63** » Fri Sep 26, 2008 8:20 pm

Ive had over a dozen IBM/Lenovo-branded power supplies over 10 years and I've never had one go bad.

Radioguy · #20 Post by **Radioguy** » Fri Sep 26, 2008 8:37 pm

What about coolness? My T61 shipped with a 2-pin 65W model 92P1155, and it gets pretty hot. My assumption is that a 90W model will be cooler, and might improve system performance a bit.

I just want to know, if anyone else knows, which performs best/runs coolest.

Thanks.

EDIT: 92P1155 isn't even in the list above. Does anyone know who makes it?

Wentworth · #21 Post by **Wentworth** » Tue Sep 30, 2008 7:08 am

The 90 w is slightly cooler than 65 w when used on the same machine, due to the larger surface area for heat dissipation.

Radioguy · #22 Post by **Radioguy** » Tue Sep 30, 2008 7:28 am

Wentworth wrote:The 90 w is slightly cooler than 65 w when used on the same machine, due to the larger surface area for heat dissipation.

That goes without saying.

I mean, which of the different 90W models runs coolest. (or has a better build reputation)

Radioguy · #23 Post by **Radioguy** » Fri Oct 03, 2008 7:47 pm

If someone can identify the FRU I posted, I'd appreciate it, because I have no idea of the mfgr. It does run a little hot for my liking. If I get a 90W, I might veer away from the same mfgr.

What's funny, is that I have a Delta for another brand laptop, and it runs as hot as hell. (and it's a 90W too!) I was considering getting the next version up (150W), but that's like twice the price. Not worth it when my T61 is my primary machine.

rbena · #24 Post by **rbena** » Fri Oct 03, 2008 9:52 pm

Ah the hot running AC adapter - a topic near and dear to many of us.

There's a previous discussion at the link below:

http://forum.thinkpads.com/viewtopic.ph ... highlight=

and apparently a more robust discussion exists elsewhere on the forum.

My experience has been that various AC adapters may not perform at the same temperatures, and this even holds true with identical adapters (same mfgr and W-rating). So it's best to check the adapter when first using it and then periodically, to see if it's maintaining a desireable temperature. Electronics running blazing hot will at best have a shorter life, and worse may fail - and melt or burn something next to it.

It's also good to select a unit that is conservatively spec'd for its task. You'll not stress it heat-wise, particularly when the ambient temperature is higher and it is operating under heavy load.

Radioguy · #25 Post by **Radioguy** » Fri Oct 03, 2008 10:20 pm

Agreed. I assume I was shipped the 65W due my choice of the X3100 over the Quadro, but a GPU isn't the only thing that can draw power.

I think I need a 90W in general. I'd just like to know which brand I currently have, and whether any of the 90W choices have a good rep.

First Light · #26 Post by **First Light** » Fri Oct 10, 2008 7:55 pm

Wentworth wrote:The 90 w is slightly cooler than 65 w when used on the same machine, due to the larger surface area for heat dissipation.

How do you use different size power bricks on the same machine when the plug for the 65w and 90w power bricks are different sizes?

Wentworth · #27 Post by **Wentworth** » Fri Oct 10, 2008 8:00 pm

@First Light, the plug is actually the same for 65 w and 90 w adapter, only the actual the size of adapter brick is different.

First Light · #28 Post by **First Light** » Sat Oct 11, 2008 2:34 pm

Wentworth wrote:@First Light, the plug is actually the same for 65 w and 90 w adapter, only the actual the size of adapter brick is different.

Well, I'm confused (which is not unusual).

I have a T42p with a 90w adapter and an X60s with a 65w adapter, and the plugs are different sizes on these two adapters.

comptiger5000 · #29 Post by **comptiger5000** » Sat Oct 11, 2008 6:02 pm

That's because the machines are different. A T60 w/ 65 watt and a T60p with 90 watt are the same plug.

Radioguy · #30 Post by **Radioguy** » Sat Oct 11, 2008 6:38 pm

OK, I have a 90W one now. It's 93P5026 / 92P1109. The word "JET" is on it. Is that the manufacturer? Are they good?

I'd still love to know the manufacturer of 92P1155 / 92P1156. It still ran hot to the last second.

65W versus 90W AC power adapters

65W versus 90W AC power adapters

Who is online