Thinkpads Forum

What is the difference between the 65W and 90W adapters?

When and why would you choose to use one over the other?

Thanks

65W adapter is smaller and lighter. 90W might be useful if you have a heavily-loaded machine that can use up more than 65W while operating and charging at the maximum rate at the same time.

Note that some airline power outlets cannot handle 90W of power output, and using a 90W power supply might necessitate removing the battery (so that the ThinkPad does not charge at the same time as it operates).

Which one runs hotter under normal use?

Reason I ask all these questions is because a 65W came with the T61 and now Lenovo is sending me a 90W (for free) because I was involved with the May T61 delay fiasco.

Would it make sense to use the 90W one at home and the 65W one when traveling or vice versa?

That's exactly what I would do.

My X61 (when it finally arrives) is coming with two 65Ws, but one of my colleagues just received his T61 with a 90W (very nice!) so I might do a comparison once I have my X.

cflutist wrote:Which one runs hotter under normal use?

I have both the 65w and 90w for mine. Even though the 65w uses less power, obviously, it nevertheless feels quite a bit warmer, probably because it's significantly smaller. In fact it can get pretty hot!

You typically get the 90W version with 15" and/or 'p' models that have high-powered graphics chips. These components have big power requirements.

i have both, and a 120w Kensington...there is hardly a difference in charge times between all 3. The 120w shows up as a 90w charger in the Power Management software.

RonS wrote:You typically get the 90W version with 15" and/or 'p' models that have high-powered graphics chips. These components have big power requirements.

Well I don't have either (have T61 14.1" WS and X3100 graphics) and also don't do gaming.

Do have another question though. I think I remember SkiBunny telling me that using a 72W adapter (that I had several of from my old T23 and T41s) with the T61 would damage it. But why is it okay to use a 90W with a T61?

Sorry to be so dense, but I'm just curious.

cflutist wrote:Do have another question though. I think I remember SkiBunny telling me that using a 72W adapter (that I had several of from my old T23 and T41s) with the T61 would damage it. But why is it okay to use a 90W with a T61?

For a long time (since at least the 600 series) the standard input voltage for most Thinkpads was 16 Volts DC.

For the T6x series, the voltage has gone up to 20 Volts DC, which reflects the higher power needs on the latest multi-core processors and their support chips etc.

The 72W power pack delivers 16Volts @ 4.4 Amps, the 90W power pack delivers 20Volts @ 4.5 Amps.

The 72W unit is not suitable for a T6x Thinkpad as it does not provide enough input voltage (and also has the wrong sort of DC plug on it).

Cheers,

Bill B.

Thanks for the explanation.

One last question, how many volts at what amps does the 65W adapter deliver?

Given that you're asking about the T6x adapter, the voltage would still be 20V. The current capability is then calculated by:

Amps = Power (Watts) / Voltage

So, for the 65W adapter, it should be able to supply up to 3.25A. These parameters should be listed on the adapter itself.

As to which one would run cooler, generally that would be the 90 watt unit. Simply because it would not be operating close to its maximum specification. It will also NOT consume more power than the 65 watt supply (assuming the conversion efficiency of the designs are equal).

Thanks everyone, I learned quite a bit tonight.

On the rear end of your thinkpad, there is voltage info. written near the power jack hole.

Wow, that's neat, it says 20V

Thanks again

So from what I'm reading here does that mean a 65w adapter will work on a T61 with NVS 140? Definately would like to carry a smaller adapter if possible.

Check the bottom of the laptop. It should have the required current rating next to the voltage. If it's 3.25A (or lower), then the 65 watt adapter will be okay. If it's more than 3.25A, then you would be overstressing the 65W supply and that would NOT be recommended.

cflutist wrote:

RonS wrote:You typically get the 90W version with 15" and/or 'p' models that have high-powered graphics chips. These components have big power requirements.

Well I don't have either (have T61 14.1" WS and X3100 graphics) and also don't do gaming.

Do have another question though. I think I remember SkiBunny telling me that using a 72W adapter (that I had several of from my old T23 and T41s) with the T61 would damage it. But why is it okay to use a 90W with a T61?

Sorry to be so dense, but I'm just curious.

The connectors are not the same on T2x-T4x and a T6X.

Their voltage output is also different. Thats the reason why you cannot and should not interchange.

LIVE4SPD wrote:So from what I'm reading here does that mean a 65w adapter will work on a T61 with NVS 140? Definately would like to carry a smaller adapter if possible.

a 65W wil do on a model without dicrete GPU.

You could also remove your DVD drive and thereby save a bit of power.

So 65W is for models with a Intel Shared Graphic.

I should however work at least when not charging empty batteries while working, also on model with ATI and Nvidia

LIVE4SPD wrote:So from what I'm reading here does that mean a 65w adapter will work on a T61 with NVS 140? Definately would like to carry a smaller adapter if possible.

ive done this with the 65w charger, and there is no problem.

Excellent. I'll have to try that 65 watt adapter.

Thanks for the info