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'Laptop use in car'

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  • 'Laptop use in car'

    Please let me resume the contents of this earlier thread at

    and furnish the following detailed how-to description proven in practice.

    There is a catch, however, due to more recent mysterious industry (political?) product decisions, and I am looking for ways to get around their negative effect. If this subject interests you, please take a few minutes of your time, it will probably be worth it. I am presently travelling and will attempt to monitor this thread - if it develops into one - as regularly as possible.


    A notebook in your car is realistically feasible. I have had one for years in my Audi A4, set up according to my own ideas, and I have never regretted the investment.

    Basically, what you need to do is this:

    You should have a second battery in parallel, for your notebook and other extras (like car stereo). Regarding discharging, you ought to add a separator *relay* that makes sure the additional consumers (notebook & co) can only draw from the second battery. This way, the car's default electric balance will be maintained. (Don't use a separator
    *diode*, they are too likely to die from heat.) Regarding charging, you ought to replace your alternator by the most powerful type available - like a 120 A type instead of a 90 A. For situations where you don't drive much but use your extras a lot, a separate powerful charger (that can deliver a current 20 % the size of the battery's capacity - like 16 A for an 80 Ah battery) is useful, if you have access to an electric powerpoint. Also useful would be an instrument to monitor the second battery's state of charge. This part, I haven't put into practice yet.

    Then you get yourself a docking station for the notebook and put it into the trunk (details with regard to the mechanical part in the next chapter). The power you get through a fx Kensington 33196. Exchange the cigarette lighter plug through one of the Nato type, they are more contact-secure. Near your steering wheel, you place a monitor (fx Xenarc), mouse and keyboard. I wouldn't go for touch-sensitive monitors - on a 7" monitor, you would need a toothpick to make your choices. The mouse's pointer is more convenient.

    According to my experience, the harddisk is not really sensitive to the movements appearing during regular driving. What is sensitive, though, are the many tiny contacts between the notebook and the docking station. In order to protect them, you want to prevent movements, vertical ones (mainly shocks and vibrations) as well as horizontal ones (chiefly the rotary type during sharp curve driving, where your notebook wants to turn around the docking station). You can do it by taking a square plank a little larger than your notebook on the docking station, put a layer of foam rubber on it, screw a one-hooked elastic fastener belt (known from fx cycles) to one of its sides (not far from the docking station, and 'parallel' to it) and an eye on the opposite side. When you have put your notebook onto the docking station, you span the fastener belt across the notebook on the docking station and hook it into the eye, thus pressing the notebook against the docking station. This way, the ensemble is largely immobilised and shockproof. Obviously, you could also invest more thought and actions into general crash security. So far, I have postponed this part of the venture.

    From now on, you can use all the features of your notebook in your car. (We'll talk about the internet in the remaining chapters.) Fx, you can connect its audio output to your car stereo's auxiliary input and will enjoy your own 128 bps music in FM quality. (In some cases, you may need a module, see You also can connect a GPS antenna and software and use your monitor as a GPS system. (You can even install a video-recording system and have the video shown on the monitor, just like a police car.)

    Now comes the part which used to be easy until 2G, but has been made impossible since 3G - god knows why the powers-that-be (economy, politics?!) have chosen to remove an essential part from the market. I'm talking about the connection to the internet. Up to 2G, the formula was this: Best is to have a handheld cellphone and have its carkit properly mounted, including an external antenna. If you then also connected your notebook to the carkit's central unit, it didn't take much time to make it communicate with the cellphone's modem. The only drawback was that up to 2G, there was nothing but the GPRS transmission standard - and that was way too slow.

    So you think 3G would bring the solution? In a way - data speeds have gone up considerably, cellphones (maybe not all types) have an HSPA modem. The problem is (what I say now is based on my degree of understanding - if you detect an error, please advise me): Today's wireless bluetooth carkits called SAP (SIM access profile) only support interaction with your phone's SIM card and the audio periphery (mic/speaker), not however the HSPA modem. So you cannot use it. What remains is to buy a separate Huawei modem, but then you won't use your external antenna, and you also need to swap SIM cards with your cellphone (unless you pay extra for 'duo SIM cards').

    And this is where I would ask you to become active. Please talk to company's like Kensington, Jotto Desk, Diversified Products, but also potential newcomer businesses and schools educating electronic professionals, and draw their attention to this missing link. Here in semi-totalitarian Europe, I have used all my possibilities and have ultimately gotten nowhere. Is America still the 'can-do country'?

    This is an open message in this sense: You may spread it for purposes that may be appropriate to promote my own intentions.

  • #2
    I did exactly the same thing at first with the laptop but instead i put the laptop underneath the seat and used an external touch screen monitor to mount to the dash.