Thinkpads Forum

Safely interchange & use T61 90W, X61T 65W, Ultraslim 90W ?

The 65W is 3.25 A (came with my X61T) and 90W is 4.5 A (Came with T61).
Also have the Ultraslim travel one which is 90w 4.5 A
(All being 20V).

Can they safely be interchanged and used for the other? I know charging slows with lower power adapter.. Wondering if its all safe?

PS: I am guessing it is but just a thought.

The answer is mostly yes, but with a few exceptions.

First of all - anything that specifies it needs the 65W adapter can take the more powerful 90W adapters with no issue.

Vice-versa is not always true. Generally, Lenovo tends to provide the 90W adapter with the more power-consuming units with discrete GPU (Intel GPU T series will come with 65W, discrete GPU T series with 90W). Some W series with quad cores and even more powerful GPUs will come with 135W or even 170W!

In principle Lenovo does not advise using the 65W PSU with any machine that originally came equipped with the 90W. However, in most cases I found that it's fine to use them even if you have a discrete GPU - the laptop, even at its highest, does not draw anything near 65W. But my experience has been limited to the older T series with dual cores. I would probably not use them on a quad core model which "demands" 135W.

Another thing - don't use any T series docking station with anything lower than 90W. It will leave them underpowered, and probably some of the ports will not work.

Finally, if you have a habit of using laptops with the battery disconnected (only on AC), you should only use the 90W. With 65W and no battery the CPU will be permanently throttled to the lowest speed (another precaution by Lenovo). Though I don't like this practice of battery-less usage in general.

Thanks Dr_St. Appreciate the comprehensive write up

I figured most of the above was right, but wasnt sure. With the W510 for my dad we realized the 90W just wouldnt cut it. He complains about it now, but I told him wait it out for the T510 that was arriving. (We wanted the FHD display for him).