ThinkPad X41 Tablet running on 9 Volts!

[ReCreate]

Just an interesting story I thought I'd put up. Earlier this day, I noticed that i had a 9-volt external DVD player battery. It charges with any DC input from 9 volts to 16(or more) volts. (So i can use my wireless router's 9-volt DC charger to charge it) I first intended in making a cable to connect it to the router, to see if it can run on battery. But i noticed the connector fits into my tablet fine. So out of random curiosity. I connected it. And long behold, the computer recognized that it's on AC power. Though when the battery was removed it powered off. Not enough current.

So i made the cable to connect from the external battery to the computer(from parts i had lying around) and it worked!

The battery is a 9-volt 5.4 amp hour lithium ion battery. We bought it back in 2003 to use it on a portable DVD player, but *never* really used it.

Here's two pictures of it.
http://i.imgur.com/2A1Mx.png
http://i.imgur.com/k8D7n.jpg


I just needed to turn down the backlight and CPU, otherwise it isnt quite enough voltage/current still. But it works. Who thought it would work with such low voltages? (though i haven't tested too many other things, like USB power. etc)

Admin edit: Removed 660KB inline image. Please keep them <50KB.
Edit: Gah. I apologize about the file size. I keep forgetting. >_<

[automobus]

That is amazing! Do you have the ultra low voltage processor?

[topmahof]

http://www.small-laptops.com/ibm-lenovo-thinkpad-x40/

I thought only some x40s came with the ULV processor.

That is amazing that it's running off of a 9 volt battery.

Dave

[ReCreate]

Nope, It's the regular low voltage processor. It's undervolted to voltages lower than that of the low voltage processor though. x3 I had to lower it to .7 volts and 600mhz in order for it not to shutdown due to too little current.(i might be able to run it on a higher speed, but i wasn't bothered to do testing) It runs fine at full-power with a 12-volt lead acid battery. But the battery can't charge (for obvious reasons) and discharges while connected.

[topmahof]

It's cool that it even runs off of a 9-volt battery.

Dave

[automobus]

It runs fine at full-power with a 12-volt lead acid battery.

And that was going to be my next question. That's neat, that in desperation one could run it straight from a vehicle lighter/power socket.

[ReCreate]

Actually, I did that. It works fine, only problem being that it discharges the battery while connected. So you need to disconnect the battery, meaning that if the power is interrupted the computer will obviously shut down. Which is quite inconvenient.

[automobus]

I recently tried a powering few ThinkPads with 12V. T23, T43, X22 seem to operate without a problem (only tested for a few minutes, not stress-tested or long-term operation). T23 and T43 will start from 12 volts even with no battery. X22/X24 will not start from 12V, but will continue working off 12V if battery is removed while already powered on.

[sjthinkpader]

http://www.small-laptops.com/ibm-lenovo-thinkpad-x40/

I thought only some x40s came with the ULV processor.

That is amazing that it's running off of a 9 volt battery.

Dave

I only had one ULV X40 passed through my hands, a 2371-4ZM and eventually sold it. Only one model was sold in the U.S. and most were sold in Japan.