P1900 + Dell Laptop and docking station

wittless · 01-06-2006, 11:50 AM

I have been lurking here for several weeks as I have been considering building my own in-car computer. I finally was able to get all of the parts, and I installed everything into my car yesterday.

I have run into one problem with my P1900 that has me stumped. I have spent quite a while searching previous posts here and have come up dry on my particular problem. I have posted a question to the carnetix forums, but I thought I might cross post it here, as these forums seem to have more activity. I thought hopefully someone out there would know the answer.

The following is my post to the carnetix forums:

I have it powering a dell docking station with the 20v primary rail. The Docking station requires a 90w output to run. Looking at the instruction manual, I see that the P1900 can do up to 6.32 amps. All i need is 20v at 4.5 amps so I know the P1900 should be able to do it. The problem is, when I hook up the P1900 to the docking station, i get an arror that it is only running at 70w (20v x 3.5 amps) and needs 4.5 amps. Is there any way I can force the P1900 to output 4.5 amps?

If that isn't possible, the only other solution I could think of would be to wire up an auto adapter to the laptop that I know works. The only problem with that is it would take an input of 12v, and I already have a device on the 12v secondary rail. I am afraid if I hooked up the laptop to that rail, I would overload the P1900. Is there any way to get the primary rail to output at 12v also? I would prefer to not have to do it this way, but will if I have no other option.

tratpop · 01-06-2006, 01:35 PM

Im not sure if i can 100% answer this but,

But i recall that there is a ajumper in the P1900 that tells the secondary output where to pull power. and the manula tells you that if you want 12 volts then you route the power from the primary rail back into the second regulator, not sure if this means you are splitting the power?

What are you running off of the 12Voutput?

b8bboi · 01-06-2006, 01:45 PM

Why don't you just wire up the auto adapter directly to the car's power source. It should be able to take in fluctuating voltages. The laptop has internal battery so it will survive cranks as well. That's what I do for my laptop and it's been working fine. I'm using the Linds 90w adapter, BTW.

turbocad6 · 01-06-2006, 02:15 PM

I to use an opus 150 with my dell laptop & I use a lind adaptor to power the laptop itself... controlled by the opus, triggered through a relay....... the opus powers everything else,starts & shuts it down, but the lind powers the actual laptop...

MikeH · 01-06-2006, 04:18 PM

So I'll post my response here too.

Quote:

Quote:
when I hook up the P1900 to the docking station, i get an arror that it is only running at 70w (20v x 3.5 amps) and needs 4.5 amps.

Where are you getting this error? Does this appear in a diagnostic window on you laptop? Can you post a picture of the exact message so that I can interpret it? The reason I ask is, this information does not make sense. The P1900 will provide whatever current is demanded by the docking station, up to its maximum available 6.3 amps.

Quote:

Quote:
Is there any way I can force the P1900 to output 4.5 amps?

You don't have to force the P1900 to output a certain current. It will supply whatever load is demanded (think of your laptop as a big resistor) up to 6.3 amps.

Quote:

Quote:
If that isn't possible, the only other solution I could think of would be to wire up an auto adapter to the laptop that I know works.

This would not be a good idea. Your P1900 should work without having to add another adapter.

I need to better understand your "error message" and where it comes from. Also, please tell us what model laptop do you have? Some Dell laptops have proprietary power connectors with a sensor that will not allow them to work with any power source that is not made by Dell.

Bugbyte · 01-06-2006, 04:21 PM

Quote: Originally Posted by MikeH

Some Dell laptops have proprietary power connectors with a sensor that will not allow them to work with any power source that is not made by Dell.

I bet that's it. I think the power supplies that have a circular barrel with a wire in the very middle are the proprietary ones.

turbocad6 · 01-06-2006, 04:23 PM

Quote: Originally Posted by MikeH

Some Dell laptops have proprietary power connectors with a sensor that will not allow them to work with any power source that is not made by Dell.

I think that is only dependant on charging the battery, not actually powering the laptop.....

turbocad6 · 01-06-2006, 04:25 PM

that's one of the reasons I went with the lind adaptor in the first place.....

otherwise multiple power supplies shouldn't be necissary...

b8bboi · 01-06-2006, 04:26 PM

My Dell laptop (600m) actually detects the power source coming in (if it's docked) and if it's under 90w (even if it's made by Dell), the lappy will put out that "error" message.

I think in this situation, the laptop wrongly detects the rated power of the p1900 due to the proprietary connector as Bugbyte suggested.

turbocad6 · 01-06-2006, 06:29 PM

ah, so that's where that error message is coming from..... I guess the lind adaptor may be your best option afterall... I know they are made to emulate the correct dell ps & work perfect with a dell laptop....... they are pretty expensive though.....

the lind doesn't need a regulated supply & you can run it straight off battery voltage.... a dc/dc power supply can still do startup shutdown, & power all other periferals, but there may be cheaper options such as using a sequencer & point source load supply(s)... the 3.3v will be wasted & there are cheaper 12v & 5v supplies for sure....

I used an opus 150 just because I had it left over from my last install.... I don't think I would have went out & got it just for this .......

wittless · 01-06-2006, 08:07 PM

I fixed it

Reposting from carnetix forums again:

I figured out what the problem was. It wasn't anything with the P1900. Dell's older laptops have a 3 prong plug, The Inspiron 8100's used a 70W Power supply, and the 8200's use at 90W power supply. Both of these laptops can use the same docking station, but the docking station requires 90W also. The 70W power supplies only have 2 of the 3 pins wired. Ground and power. The 90W supplies have a power line, and 2 grounds. I guess that is how dell can determine the difference between 70W and 90W.

I didn't want to mangle my 90W power cable, so I used an older 70W one, not knowing there was a difference in the cable. Once I cut the end off of the 90W supply and connected it to the P1900, the laptop booted right up with no errors.

turbocad6 · 01-07-2006, 12:20 AM

I always wondered why they had 2 grounds in a 3 pin plug on the older dells....

these older dells will run on pretty much anything give or take a volt.... the newer ones have a communication & will not charge the battery by just supplying voltage alone... I though about useing a carnetix with my dell install,, but was concerned about this......