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OT Laptop power supply in Landy


Mo Murphy
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I want to get power into my old Compaq Armada M700 laptop in the landy.

I'd rather not have to use an inverter, I'd like to just plug it in the 12v socket and off we go.

Can one buy a supply that plugs into 12v one end and the laptop at the other (giving 14.8v).

TIA

Mo

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Some laptops (notably the Toughbooks) will run happily off the 12-14v present in your car, all you need do is find the right adapter end (often found in kits in pound shops) and wire it into a lighter plug. If you think about it the thing has to tolerate lower than 14v when it's running on batteries as they run down, and as such the PSU in the laptop has to be able to live with various voltages. Worth a go before splashing on an in-car PSU.

What you don't want is to stick 14v up a laptop that likes less than 12v as that may make it unhappy :unsure:

Another option is to see if there are other laptops with the same connector and very close voltage requirements, it broadens your choice of in-car PSU's and you can sometimes turn up genuine ones for not much money on eBlag. I think I used an old Fuji PSU on my toughbook, or visa-versa, and it worked fine.

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Get something like This

Paul

That's exactly what I'm using to run my Acer 2400 lap top for the GPS.

I travelled to Driffield fron Stockton on Tees last Sunday with the computer mounted on the internal security grill powered by that Maplin gadget.

mike

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I want to get power into my old Compaq Armada M700 laptop in the landy.

I'd rather not have to use an inverter, I'd like to just plug it in the 12v socket and off we go.

Can one buy a supply that plugs into 12v one end and the laptop at the other (giving 14.8v).

TIA

Mo

I have a similar problem - laptop wants 16v. My solution (which I will be trying this weekend) is to stuff a nominal 12v on it... I would be very surprised if it doesn't run (especially since the Fluke shows 12.3 minimum and 13.34 with the engine ticking over...)

I think that CPUs run at much lower voltages (around 6v ?) so I am guessing that there is some kind of solid state voltage reducer in there anyway. But when all's said and done, if it doesn't run I have lost nothing, and if it does then I have saved myself a few squids... :)

TwoSheds

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Yes all laptops have an internal PSU that takes either the battery voltage or the DC input and makes it into the various closely regulated and stabilised voltages required by the delicate chips and things - 12v, 5v, 3.3v etc. the mains adapter is just a ball-park thing really. You'd most likely find if you measured the adapter's output it would fluctuate by half a volt or more depending on the load it's under.

If your laptop wants 14.8v it should be fine with 15v although for about 1p you could solder a diode in the feed to drop ~0.6v and bring it down.

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...

You'd most likely find if you measured the adapter's output it would fluctuate by half a volt or more depending on the load it's under.

...

Last night I did a quick check on several lighter-plug PSUs and found that in every case (with no load) they were giving .5v to .8v higher than quoted. I don't think that these things are particularly well specc'd ;)

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Last night I did a quick check on several lighter-plug PSUs and found that in every case (with no load) they were giving .5v to .8v higher than quoted. I don't think that these things are particularly well specc'd ;)

Most laptops will run fine on the 12V supply in the car, no problem as long as the laptop doesn't want anything lower than 12V. The laptop has its own voltage regulator, which, as earlier stated, takes care of the differences in the supply voltage as the battery runs out. Most CPU's (Central Processing Unit, not the big box under the table at home :)) run at 5V -so no problem there. I think the only issue you might get is that the batteries won't get charged if the laptop doesn't get the right input voltage.

/tony

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