why does my laptop turn on?

Efess · 11-13-2005, 02:51 AM

this is a weird one that I havn't been able to explain...

I used to use an inverter to power my laptop with the AC-DC adapter. I had it set up so that the laptop would go into hibernate when power switches to battery, all good works great. When I start my car up, I have to press the power button to start the laptop, which was fine and dandy - expectable, because there is no "auto turn on" feature with a laptop.

Here's whats weird:

I got rid of the inverter, because It seemed un-necessary to convert power to ac and then back to DC, so I bought a DC- DC adapter on ebay ( generic )
I installed it, and voila 19-20v of 90 watts to my laptop from the 12V ignition. YAY.

The thing is now whenever I start my car, my laptop mysteriously automaticaly turns on and out of hibernate. Even when I shut down the laptop completely, when power is applied- boom there's the boot up screen...

now in NO WAY am I complaining about this, this is veryyy convenient, and im glad that it does this... the only thing that irks me is I can't explain it! I didn't change any of the power settings in the bios...not that there is any.

THe only thing I can think of is a weird surge from the DC adapter... but still, this doesn't connect to the power button at all!

Any ideas?

CdRsKuLL · 11-13-2005, 05:58 AM

it might be that you laptop isnt fully switched off when the power is killed, sometimes in a laptop bios you will find a auto on with power fail.. so it might think u had a power fail.. if you see what I mean.. this is the only thing I can think of at the mo

cdr

DeltaFX · 11-13-2005, 02:43 PM

Yep, it looks like a "resume on power loss".

MatrixPC · 11-14-2005, 01:27 PM

If "resume on power loss" is the cause, why didn't it happen with inverter?

Efess · 12-10-2005, 06:37 PM

thats what I wanna know... so im not the only one that's totaly confused by this... and in my bios, there are very limited options- with no option for resume on power loss

onlineamiga · 12-20-2005, 10:03 AM

Sounds to me like ur a very lucky b****rd !!! People go to great lengths to get working what has just automatically started working for you

Wish mine would do that!

TurboBoos · 01-20-2006, 01:16 PM

Did you ever figure out why your laptop was powering on by itself? Mine is doing the same thing.

I too bought an el cheapo DC-DC converter off Ebay and whenever I switch my key on, the laptop fires up. Yes it is very convenient and no, I'm not complaining, however I'd love to know why!?

When applying power from the OEM AC adapter, this does not happen. I'm slightly worried that the universal Ebay adapter is "spiking" on initial power up. Hopefully there is no long term damage caused by it. Sometime when I'm bored I might try to meter it and see.

For the record I'm using an IBM ThinkPad T21 with a universal adapter model SC1220.

b8bboi · 01-20-2006, 01:21 PM

Weird ****. Mine is doing the same thing, too. I got a Dell 600m hooked up to a docking station. Mine doesn't have "auto resume on power loss" or whatever. Hopefully, it's not causing long-term damage, either.

The thing is it just started doing this about 2 weeks ago. Before that, I had to push the relocated power button to turn it on.

If anyone figures out why this happens, let us know.

techyguru · 03-26-2006, 09:42 PM

You are just learning to channel your thoughts into the electronics you love.

just kidding, and yes I know this is a dead thread but had to say it.

TheDeepFryedBoo · 04-10-2006, 12:46 AM

If it is a cheap adapter then maybe it does a bad job at maintaining a constant voltage level. When you start the car the starter motor draws a lot of power and can drop the voltage a couple of volts. Maybe the adapter is not compensating for this and is over/under supplying voltage to the laptop. On desktops this situation (brownout) can cause the PC to reset. Maybe this is happening for the laptop. On a laptop when the AC adapter is unplugged the computer senses a lack of power and goes to battery. But what if this drop in voltage did not trigger the laptop into battery mode but does not provide enough power to keep the circuits on for the charger, clock, button sensor... maybe that’s the problem.

b8bboi · 04-10-2006, 12:56 AM

Quote: Originally Posted by TheDeepFryedBoo

If it is a cheap adapter then maybe it does a bad job at maintaining a constant voltage level. When you start the car the starter motor draws a lot of power and can drop the voltage a couple of volts. Maybe the adapter is not compensating for this and is over/under supplying voltage to the laptop. On desktops this situation (brownout) can cause the PC to reset. Maybe this is happening for the laptop. On a laptop when the AC adapter is unplugged the computer senses a lack of power and goes to battery. But what if this drop in voltage did not trigger the laptop into battery mode but does not provide enough power to keep the circuits on for the charger, clock, button sensor... maybe that’s the problem.

Nah, for this scenario to happen, the laptop has to be turned on in the first place, which it's NOT. My lappie has been running fine since this "problem" happened. No reset whatsoever. Of course I'm not complaining at all.

TheDeepFryedBoo · 04-10-2006, 01:26 AM

Maby when the computer is on it monitors the voltages and can choose when to goto battery but when it is off the computer has a simpler, less effective methed that does not take into account partial power drops. This is a posibility. The AC adapters provided by the maker are much more advanced and cut off the power completely if there is a problem. On the other hand, cheap adapters are somewhat unpredictable. If you want a good adapter use an iJuice or knowen as iGo. They work in cars, planes and anywhere in the world. The price is worth it.

young gun · 04-18-2006, 05:49 PM

so basically all the advantages without installing an sdc unit? has there been any long term problems with this?

TurboBoos · 04-18-2006, 07:25 PM

OK here's my long term report on this problem:

I've had the laptop installed in my car since december using the same cheapie DC to DC converter. The laptop still works great both on AC and on battery with no noticeable battery degredation. I'd say 3 out of 4 times, the laptop "magically" turns on with the ignition. Convenient? not really. It has to work 4 out of 4 to be convenient. So my advice would be don't rely on it as a startup controller.

Recently I decided to invest in a real startup/shutdown controller (M2-ATX modified to work with my lappy) but here lies the new problem. When I turn the ignition on, the laptop fires on its own as before... but then the pulse from the M2-ATX turns it off defeating the controller. Aargh.

Back to the drawing board on this one.

WarDriver · 04-28-2006, 08:53 AM

Why not just do a remote switch wired to the power on button of you laptop?

Its easy and you can make it so your laptop is still useable. Check out some of my pictures...

http://www.mp3car.com/vbulletin/show...255#post806255