How can I use a small 90W power adapter with a ThinkPad W530?

Question

I have a Lenovo ThinkPad W530 computer. The 170W power adapter it comes with is huge!

I tried to plug in an old 90W adapter -- which is much smaller -- to the computer but immediately when it starts booting an error message appears:

 The connected AC adapter has a lower wattage than the recommended
 model which was shipped with the system. To boot with the AC adapter,
 please connect the AC adapter which was shipped with the system.
 Press Esc to continue. 

When I boot up the system I see that the computer is running on battery.

Is there some way I can power my computer with the old standard ThinkPad 90W adapter?

Comments about answers

Yes, there are ways to achieve this, but they require a little hardware work.

The computer seems to use the resistance between two points on the adapter tip to determine which adapter it is. By manipulating this resistance the computer can be made into thinking a 90W adapter is one it can accept. The internet reports that this works fine unless the computer is under very heavy load.

I will post the two ways that seem easiest to me myself. I do this to get the information available on this site. I only found it after searching for it for a long time on the Lenovo discussion forum, which I find rather hard to navigate.

The ThinkPad W520 has the same issue.

Answer 1

The following is what seems to be the simplest solution. I have tried this myself and it seems to be working fine, but I can't myself judge whether there are any problems with it.

User Tamazerd posted this solution on the Lenovo discussion forum:

I used a small jump wire from a kit i had but anything will do. Just make sure it wont short against anything else!

I located where the middle pin of the power-plug is connected to the motherboard (blue cable) and used the jump wire to bridge it with one of the ground/negative ones (black).

This works good for me so far. The only problem i can see with this is if the computer now thinks that all adapters are 135W ones, even the 170W adapter. This is something i havent been able to check.

WARNING: Modifying electric equipment might be dangerous! Do this on your own risk and only if you know what you are doing.

Answer 2

If someone is still wondering how to do this, its fairly simple. The 90W charger has nothing(!) connected to the middle pin, inside, there was a plastic cap over it. So I opened the connector, soldered 1500 Ohms resistor to the outer cap (ground) and to the pin. Used hotglue and heat shrink to cover. Works wonder and is quick mod.

Answer 3

It's possible to make a custom power extension wire for a 90W adapter that is accepted by the computer.

This seems to be the best solution, but you have to buy some components and do some soldering. I haven't tried this myself and I don't really understand the details, but I post it anyway.

The solution is explained by user dragon-fly in this post:

you can do it two ways:

hardwire solder it to another cable by shorting the ground pin with the center pin or do it the way i did it, make an adapter cable with a DC Jack plug from a laptop, like the one i made for huberth.

User johnfv clarifies in this post:

As for figuring out which wires go where, I used a meter to make sure I had the right wires and pins. As dragon-fly pointed out, the key is to connect the center (signal) pin to the negative/ground. You'll also want some heat shrink to keep things neat after you've completed your connections.

The component that is necessary is a Power Cord Plug Tip for Lenovo Z60m Z60t AC adapter as mentioned by user johnfv in this post.

WARNING: Modifying electric equipment might be dangerous! Do this on your own risk and only if you know what you are doing.

Answer 4

yes i know this is an old thread. (Lenovo W510) Between the center pin and - there is a 1.5K resistor! It is not full short circuit! It is better to make an adapter cable if you get a plug. Possible some people on eBay selling adapter cable. This is lenovo 170 W power adapter.