Carnetix P1900/P2140 and IBM T40 Laptop Power Question

l00kster · 10-03-2007, 12:57 PM

I have searched for Carnetix P1900/P2140 and laptop (didn't find much) and read a bunch of the power laptop threads, but I'm still a bit confused about this.

Basically, I have a laptop (IBM T40) and I want to power it in my car with a Carnetix P1900 or P2140. How do I wire something like this? Does the Carnetix act as the power supply? So do I just solder the ends of the Carnetix directly into the laptop and bypass the built in power supply? Or does the Carnetix work like the AC/DC adapter and I have to hack up my AC/DC adapter cable and cut the DC plug off and wire it up to the carnetix and just plug it in? If I do it this way, how does it know when to auto on and off? Is that a seperate connection the Carnetix has that I solder to the on/off button?

Edit: After reading the responses, I just checked and my AC/DC adapter says 16V @ 4.5A. The P1900 can only do 18/19/20 and the P2140 can only do 12/18.5/20. Can I still use the Carnetix?

turbocad6 · 10-03-2007, 01:19 PM

the carnetix will be the power supply, you can get another plug for your laptop, just the tip, radioshack like $4 or so, the original ac adaptor is not used in the install unless you choose to cut the plug off of that instead of buying a plug.

you will need to solder wires to your power switch to have the carnetix start & shutdown.

DarquePervert · 10-03-2007, 01:21 PM

Yes, the Carnetix acts as the power supply. It would basically replace the power brick AC adapter.
Now, you need to look at your existing power brick. On it, there should be a label. On that label, there should be an output voltage. What is that output voltage (or voltages, if there are multiple voltages listed). That will determine whehter the Carnetix will power your laptop.

Also, if you want the Carnetix to power the laptop on/off with the ignition, you can wire up the power button of the laptop to the Carnetix. Some don't want to take their laptop apart, however.

It sounds like you have the general idea as to how the Carnetix works.

turbocad6 · 10-03-2007, 01:37 PM

I think the ibm's are 19v... there are docks available for them too if you don't want to open the unit, the power switch on the dock can be modded instead...

l00kster · 10-03-2007, 02:02 PM

I just checked and my AC/DC adapter says 16V @ 4.5A. The P1900 can only do 18/19/20 and the P2140 can only do 12/18.5/20. Can I still use the Carnetix?

DarquePervert · 10-03-2007, 02:03 PM

Doesn't look that way....

l00kster · 10-03-2007, 02:19 PM

In that case, if I see a AC/DC Combo adapter for my laptop where 1 end plugs into the laptop and the other end plugs into the car cigarette adapter (thus getting rid of a power invertor). Is there a way to hard wire this into my car so I don't have to use the cigarette adapter? I'm assuming that cigarette adapter can just be cut off and splice the wires into a fused 12v directly to my battery and a ground/chassis right?

turbocad6 · 10-03-2007, 03:36 PM

yeah, you can cut the plug off, then check which of the 2 wires are connected to the center lug on the cig adaptor(should be center wire), that will be positive... make sure you do something to always be able to identify the positive, then connect away... instead of the carnetix you can then just use a simple startup shutdown controller to control the supply & the startup/ shutdown.

vipervin · 10-20-2007, 01:06 AM

Quote: Originally Posted by l00kster

I just checked and my AC/DC adapter says 16V @ 4.5A. The P1900 can only do 18/19/20 and the P2140 can only do 12/18.5/20. Can I still use the Carnetix?

yes you can. i have the thinkpad x24 with also the 16V adapter. like you, i wasnt sure if it would work.. but i put my P1900 on the 18V setting and it works like a champ. been using it for over a year with no problems.

thinkpads are tanks

only problem i still have is trying to figure out how to get to the power switch for the remote power on thru the carnetix. that switch on the thinkpad is near impossible to hack into

DEM_968 · 10-23-2007, 09:32 AM

Hello,

Had similar questions regarding my IBM T42 laptop, so I queried CarNetix for sometime regarding this and got the following answer for the CarNetix P2140:

"If you connect s 60k resistor between JP1 pins 2-3 you will get ~16V at the primary output.
MikeH
CarNetix"

Regards,
DEM.

turbocad6 · 10-23-2007, 10:06 AM

woh, that's def good to know... mike should incorperate this into the supply as a feature as there are more & more of these 16v laptops... including mine

hari-bhari · 12-23-2007, 07:43 PM

did anyone get that 60k resistor trick working for your carnetix supply. ive also got a thinkpad and want to run at 16.5v but i donno how.

also ,were any of you thinkpad owners able to tap into the power button. its just like a keyboard button so i dont know what two leads to jump.?

colbyau · 01-22-2008, 01:45 AM

From Carnetix support site:

Quote:

"In the next several weeks we will be introducing a way to change the primary output of the P2140 to voltage to anything between +12V & +20V. This is aimed at the laptop users. We will make an announcement soon regarding this "voltage programming kit". These are due around April 15th.