question about how hot the mains power supply gets on a T41

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bunder · #1 Post by **bunder** » Fri May 28, 2004 1:38 pm

hi folks

Newbie here again...

How hot does your thinkpad main power adapter get?

And how safe is it really to leave it always plugged into the mains.

Had mine on for about 10 hours today and it is quite hot. but after taking it off the mains, it cooled down in about 10 minutes.

How do others use their thinkpads with the mains?

thanks

Leslie

akeskira · #2 Post by **akeskira** » Fri May 28, 2004 2:32 pm

I have three adapters; one at work, one in bedroom and one in living room. I never unplug them unless I have to take one with me on a trip. They get a little warm but so far (4 years) no problems whatsoever.

Antti

Greg Gebhardt · #3 Post by **Greg Gebhardt** » Fri May 28, 2004 2:35 pm

I have never unplugged mine.

cynic · #4 Post by **cynic** » Fri May 28, 2004 3:10 pm

Never unplugged, slightly warm-- definitely not hot. This is the American adapter in a fairly cool climate (Southern California)

hausman · #5 Post by **hausman** » Fri May 28, 2004 3:55 pm

Anyone know how much electricity (watts) is consumed by an idle TP power brick that's plugged into the AC mains (but not powering a TP)?

Roy_W · #6 Post by **Roy_W** » Fri May 28, 2004 4:23 pm

In general I have the transformer all day long, either at work or at home.

When I unplug the transfo after work, I must admit it is quite hot. Not that hot that it burns or untouchable but it does seem to be overly hot.

Then again there are a few laptops at work and all of the transfos are hot
after a period of 1 hour or more.

ian · #7 Post by **ian** » Fri May 28, 2004 4:25 pm

hausman wrote:Anyone know how much electricity (watts) is consumed by an idle TP power brick that's plugged into the AC mains (but not powering a TP)?

Zero volts amps watts joules/sec litres

hausman · #8 Post by **hausman** » Fri May 28, 2004 4:34 pm

ian wrote:Zero volts amps watts joules/sec litres

That can't be. An adapter that's plugged into the AC mains is warm. It takes power to make it warm.

Power bricks use a small transformer to bring the voltage down from 120/240V to 12V. Even if they're not connected to any device, if they're plugged into the AC mains the primary coil of the transformer is still connected across the AC line and therefore still draws some power.

tyipengr · #9 Post by **tyipengr** » Fri May 28, 2004 4:35 pm

I looked up the specs for similar 100V-220V brick type AC adaptors w/72 watt output and they have efficiencies that range from 80-85% percent at, what I am guessing, full load. I'd like to think that IBM AC adaptors are at the higher end of the efficiency scale so lets say they lose 15% while being used. 15% of 72W is 10.8 watts so worst case scenario a plugged in AC adaptor thats doing nothing will waste a max 10.8 watts. Thats a very rough estimate btw.

10.8watts * 24 hours a day * 365 days a year = about 94.6kW-hours wasted a year based on that rate.

My local price per kW-hour is about 13 cents/kW-Hr so thats about $12-13 dollars a year.

This is MAX btw...it is probably less.

ian · #10 Post by **ian** » Fri May 28, 2004 5:04 pm

I was rather under the impression that this power drain only occured if there were a complete circuit - ie; that tha laptop was connected. I COULD of course be wrong, and will no doubt be lambasted for my ignorance. After owning UNOs one becomes used to this of course - which is not to say I believe you either.

bunder · #11 Post by **bunder** » Fri May 28, 2004 5:04 pm

so any idea what is a reasonable hotness for the power supply.

on mine it is very warm when touched and seems to stay at the same level all the time.

leslie

tyipengr · #12 Post by **tyipengr** » Fri May 28, 2004 5:21 pm

ian wrote:I was rather under the impression that this power drain only occured if there were a complete circuit - ie; that tha laptop was connected. I COULD of course be wrong, and will no doubt be lambasted for my ignorance. After owning UNOs one becomes used to this of course - which is not to say I believe you either.

Yeah, I mean normally one would assume "hey, its not doing anything, how could it use up juice?" Which is correct if it really wasn't doing anything. But all AC adaptors are warm/hot when plugged in, meaning they are dissipating some kind of heat from the internal circuitry inside doing something.

ian · #13 Post by **ian** » Fri May 28, 2004 5:24 pm

Alright, I'll go for that - I always thought they were warm 'cos they were happy

I know I am...

Greg Gebhardt · #14 Post by **Greg Gebhardt** » Fri May 28, 2004 5:24 pm

ian wrote:I was rather under the impression that this power drain only occured if there were a complete circuit - ie; that tha laptop was connected. I COULD of course be wrong, and will no doubt be lambasted for my ignorance. After owning UNOs one becomes used to this of course - which is not to say I believe you either.

You might think so but my power brick is slightly warm when not in use. Slightly warm required energy, so it must be using electricity to produce that heat. My brick get warmer when in use and not charging the battery. If I have run the battery down and plug it in, the power brick get even warmer but never what I would say hot.

tyipengr · #15 Post by **tyipengr** » Fri May 28, 2004 5:48 pm

ian wrote:Alright, I'll go for that - I always thought they were warm 'cos they were happy I know I am...

Heh, I really wish that were the reason. I don't want to say it is a problem but those little ac adapter bricks running on idle around the world do add up and thats alot of wasted resources. I personally have about 30 of those things plugged in at my place, ranging from the cell phone power plugs to the huge HP printer blocks, all dissipating heat and wasting energy while we speak. But I understand that its all a trade off between the cost that the consumer is willing to pay, I personally wouldn't want to pay $$$ dollars for a super high efficiency load detecting/switched ac adapter block for my Samsuck cell phone so I could save the $2 every year. Heh.

hausman · #16 Post by **hausman** » Fri May 28, 2004 6:11 pm

tyipengr wrote:10.8watts * 24 hours a day * 365 days a year = about 94.6kW-hours wasted a year based on that rate.

Thank you. That makes lots of sense (and costs even more cents

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question about how hot the mains power supply gets on a T41

question about how hot the mains power supply gets on a T41

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