veedubya

I have been toying around with the idea of using a laptop in the car. Is there a way to have laptop plugged into 12V via cog. adaptor but to run off the laptop battery until the battery hit a certain % then kick over to the AC.

Laptop plugged in battery at 100%-11% = running off laptop battery.
Laptop plugged in battery reaches 10% = running off AC plugged in.

I briefly searched for an Adv. Power Management Tool but found nothing



thanks
veedubya

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gadu^

why not simply use a DC-DC converter and have it plugged into the 12V cig?

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veedubya

maybe the confusion was i referred to AC power in my last line.
clearer scenario

Laptop plugged in to cig. adaptor and battery at 100%-11% = runs off laptop battery while still plugged in

Laptop plugged in to cig. adaptor and battery reaches 10% = runs off cig. adaptor

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Nerd2

Why would you want this?

I would think it may be possible to do in VB..... possibly.....

EDIT: Actually "AC" may be directly linked to battery, you'd have to have some sort of relay?

lbridges

It would help if the scenario for use was explained. For example, if all you wanted to do was have a way to sit in the car and run the laptop for an hour or so without draining the car's battery, then just insert a switch inline with the power cord to the cigarette lighter.

veedubya

Not sure a better way to explain.

If laptop battery is bewteen 100% - 11% it will run off the laptop battery
If it drops below 10% then I would like it to run off the cig. adapter.

As it is i have a 2nd battery that will be used for laptop and possibly 7" Lilliput.

Just trying to think of a way to use laptop battery to a certian point before switching over to the 2nd car battery

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Nerd2

Errr, the question we have isn't 'what do you want to do?', it's 'why do you want to do it?'

veedubya

does my reason need to be more clearer than this

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Bugbyte

What's wrong with a manual switch? You switch it when the OS warns that your battery is low.

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gadu^

Also, a laptop can run on a car battery for a looong time...
I don't see any use of this...

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Shai-Hulud

I'm coming in late on this one but.....

If you constantly run your laptop off the battery discharging it continuously it will prematurely shorten it's life. In a few months you'll notice shorter run times before needing a fresh charge. Depending on the type of computer you have, say a desktop replacement, they aren't necessarily meant to run for significant periods of time on battery.

My suggestion is run your laptop off your car's power using an inverter or dc-dc adapter. Use your laptop's battery when the car isn't running.

spud42

if you put power into the back of a laptop by what ever means you try, either the manufacturers dc adaptor to a cig socket or via an inverter and laptop psu . it doesnt matter. the laptops power/battery management system will use that power and also charge the laptop battery. in other words it is part of how the laptop is made and unless you modify the power circuits it cant be altered by software alone. the laptop battery wont be used unless external power is removed. you could make a circuit with a relay that is controlled by software and monitors the laptops battery level and then switches to ext power at the point you want . but as stated before the laptop battery isnt going to take a lot of deep discharge cycles ie down to 10% or less too often. i am looking at a dell d620 dual core laptop right now and its battery is 11.1 v and 85 WHrswhich means a capacity of 7600 mA approx. this gives me approx 3 hrs of use. your car battery would probably power the laptop for over 24 hrs straight. then when it gets low you would then have the laptop battery kick in and have 3 hrs to get the main battery recharged.. the laptop battery would act like a UPS.... if your second battery is charged via the car as per normal then you would probably never need the laptop battery. so why do you want to do it the way you said?????

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