This topic has been discussed in this thread:  and this thread. 

I have not seen a satisfactory reason why the notebook cannot operate from 90W in a reduced performance mode.  The conditions that cause a 135W power draw are rare. For light use my W520 draws 15-20 watts. As a thought experiment, consider what would happen if you had a 90W adapter attached, and suddenly the notebook tried to draw 135W.  The adapter would shut down due to over-current. This is exactly the same scenario that would occur if I unplugged the adapter while operating. The notebook is designed to instantly switch over to battery if the AC power goes away. So there is no risk to the computer. Maybe if the adapter is poorly designed, it could be damaged.

I challenge Lenovo to provide a technical reason why the W520 and W530 cannot operate off a 90W supply in a reduced performance mode.  I believe a good portion of the 135W is for charging the battery. So if the power drain exceeds 90W, stop charging the battery. 90W should be more than enough to operate the notebook only under any circumstance. Under most circumstances, it can operate the computer and charge the battery.

 This thread describes mods that will trick the notebook into thinking it has a different capacity power supply.

i just tested power draw of my laptop and under turbo boost, integrated graphics only, the laptop only draws 80 watts at the wall. there is no reason for it to not run on 90W adapter without discharging the battery, in fact, there is a 10W balance to charge the battery.

The most i made this laptop consume was 151W under full OCCT Load, with lenovo turbo boost enabled, Throtlestop forcing even higher turbo, and loading both quad core and k2000m to the limit using OCCT PSU Test, and testing all cores including logical cores, for only 30 seconds, after which the second level turbo boost drops off after the cpu has heated up and the system draws only 130W at the wall after that.

given my tests were done on a W530, i shall post my results here.

Bottom line: Lenovo power manager has no freaking clue as to how much power the system actually uses when its plugged into the wall. it cant even do basic arithmetic.

 

In any case, these are my findings. on the W530, with a i7 3720 QM, 32gb of 1600mhz ram, K2000m, these are my results on power consumption.

These tests were done to see if there was a logical explanation for not allowing the use of a 90W adapter at all on such a machine. bottom line is, if throtled, there is no reason not to. limiting the use to intel gpu only and not allowing turbo boost, effectively eliminates ANY possibility of using more than 90W when not charging the battery. The proof: The last two lines of this table. 60W Max power consumption at the wall under OCCT PSU Test when the cpu is limited to 2.6ghz, and the battery is removed/not charging. PSU Test stresses both cpu and gpu simultaneously.

 

The first battery of tests were to find out what tests should and shouldnt be performed, and what numbers were accurate. it was clear that power manager had no idea how to do basic math and later tests did not include it's random numbers. it only properly aproximates power consumption when on battery, not when on AC.

 

It was also concluded that using OCCT:CPU Resulted in the same power draw as CPU: Linpack, and thus OCCT CPU Was used to expedite number crunching.

 

Without futrher ado, here are the results:

This has been an interesting thread.  I would like to add a new wrinkle to the discussion.

I have just purchased the following suite of equipment:

 (1)  ThinkPad W530 laptop (model #24384CU);  (2)  ThinkPad Minidock+ (model #433815U).

With the W530 came a power adapter rated at 170W in & 20V/8.5A out.  With the Minidock came one rated at 90W in & 20V/4.5A out.

Why is the adapter with the W530 bigger than the one with the Minidock?  Wouldn't the machine need more power when connected to the dock, when presumably it would have more peripherals connected with it?

Is it okay for me to swap them, i.e., use the 170W adapter with the Minidock and the 90W one when travelling with the W530?  (This forum has already discussed issues with using the 90W unit, but I am interested in knowing if it is okay to use the 170W one with the dock.)

Thanks.

Very interesting.  I indeed notice the different plug heads.  However, as we speak, I have been running the W530 in the dock with the 170W adapter plugged into it.  I wonder if this means that I possess the 170W version of the dock but that it came with a 90W adapter (which I have not used so far).

Cheers.

The 170W plug head can not fit into round plug dc jacks, so i dont understand what you are saying?!?!?!?!

also, the 90W adapter can not charge the W530 when you are using it, or atleast, not the quad core W530
. if you have a dual core edition, i do not know how those react, but my W530 i7 3720QM With K2000m and 32gb ram can not be used with a 90W adapter. it runs on battery only.

I have not done any testing for proof, but my understanding was that the 170W came from the total power draw when using all of the possible ports, drive bays, and devices under full load.