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Powering laptop from 12V supply — Parallax Forums

Powering laptop from 12V supply

bomberbomber Posts: 297
edited 2014-02-25 01:18 in General Discussion
So I just got an old laptop from a friend with some really good specs, and I plan on putting it on my Eddie platform as a permanent addition. The laptop came with a battery but it didn't come with a charger. I modified an old charger with the same voltage and current, and made it fit in the laptop. Sadly, the BIOS prevents the battery from being charged because it does not detect the correct charger. I was thinking, since the HDD, fans, and other components run at 12v, and all the system parts run at less, the only thing that could be using the 19V output from the charger would be the battery charging circuit, which is being shut off by software. Would I be able to power the laptop directly from Eddie's 12v batteries?

Comments

  • Mark_TMark_T Posts: 1,981
    edited 2014-02-23 13:36
    You are asking people whether a laptop you neglect to identify can run from 12V batteries?

    How about at least telling us what it is? And the info from the battery itself would be useful.
  • xanaduxanadu Posts: 3,347
    edited 2014-02-23 13:51
    With older laptops the screen back light inverter may use more than 12v.

    It's going to be trial and error. I don't think the laptop is going to accept much less than what it was designed for because lipo charging, as I myself am constantly reminded, is very picky as a safety.

    The worst thing I can think of is it "seems" to work, when in fact it isn't working properly. Then Eddie rolls off a cliff and gets damaged. That would be bad.
  • xanaduxanadu Posts: 3,347
    edited 2014-02-23 13:58
    I was about to test a couple laptops here on 12v SLA but I opted not to for the reason that the SLA can put out mega amps. I also have piles of laptops I don't care about. IF you really like the laptop then I'd say don't risk it. If you don't care about it and are feeling adventurous use a fuse rated around the same as the max output of the charger. You should be able to find the charger specs even though you don't have one.

    Also, the laptop battery probably isn't going to hold a charge, so even if you did get a charger you may end up having to get a battery. In that case I'd look for something that runs on 12v, like pico or mini-ITX.
  • kwinnkwinn Posts: 8,697
    edited 2014-02-23 15:40
    A boost converter (DC-DC) to go from 12V to 19V (assuming the laptop power brick is 19V out) should work for that, but I think xanadu has the better suggestion. Any of the small SBC`s could run from a 12V battery using a small switching regulator.
  • bomberbomber Posts: 297
    edited 2014-02-23 16:34
    I probably should have been more clear on this, the laptop is a Dell Inspiron E1705, and the battery that I have in it is a 11.1v 7200mAh battery pack. The problem that I have is that the laptop, which i got secondhand, came without a power brick. I jurry-rigged a power brick with the same specs (19v 4A output), but the dell manufacturers put an EEPROM inside their power supplies so that you ca only use dell power supplies with their laptops. BIOS blocks the charging of the battery if it does not detect a compatible power supply, though the machine is powered fine through my jurry-rigged power supply. My plan was to remove the laptops battery and tie in the laptop to Eddie's power system. I will give the fuse thing a try, and i'll see how that goes
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2014-02-23 16:59
    I would leave the original battery in the laptop if it is decent and look at using one of these adapters:

    http://www.ebay.com/itm/DC-Power-Adaptor-Auto-Battery-Charger-for-Dell-Inspiron-1720-700M-E1705-Notebook-/231132325494?pt=Laptop_Adapters_Chargers&hash=item35d08f6676

    This is what I am using for a couple larger robots.

    Robert
  • RDL2004RDL2004 Posts: 2,554
    edited 2014-02-23 17:42
    If the power jack on the laptop takes one of those standard barrel type plugs, how in the world is the laptop reading an eeprom through it?
  • bomberbomber Posts: 297
    edited 2014-02-23 17:47
    The laptop has a custom 6-pin connector (it kinda looks like a MIDI connector but the size of a normal barrel jack), 2 of the pins are used for power, 2 for ground, and 1 is a signal wire that communicates (by a 1-wire interface) to a factory-programmed EEPROM chip inside the power adapter.
  • RDL2004RDL2004 Posts: 2,554
    edited 2014-02-23 18:04
    Ah, so all the other tips are for different models. Still, probably worth $15:

    http://www.ebay.com/itm/90W-AC-Adapter-Power-Supply-for-Dell-Inspiron-1150-14R-1564-1570-17R-E1705-N4010-/390781300478


    (assuming the battery is still good)
  • trookstrooks Posts: 228
    edited 2014-02-23 18:27
    One of my most recent bad purchases was a Dell Inspiron.

    The external PS/charger has a cable that plugs into the external monitor jack.

    Tim
  • xanaduxanadu Posts: 3,347
    edited 2014-02-23 19:15
    Are you saying the power setup you have now will turn on the laptop, but not charge the battery? Or will it not even power the laptop?

    Nevermind, just saw that you said it does power it.
  • Bob Lawrence (VE1RLL)Bob Lawrence (VE1RLL) Posts: 1,720
    edited 2014-02-23 19:41
    if you haven't read this before you may find it interesting:

    inside the dell ac power adapter - a mystery revealed

    "A new DS2501 can be soldered and programmed, with a "1-wire" programming kit and a PC with an ole RS232 jack. This is described in the Dallas Semiconductor application note 177. For electronics enthusiasts that's just a bit of fun with a soldering iron and a few low cost components.

    When the programming kit is ready, next is to read the identification data from a working DELL AC Power adapter and clone it into a new DS2501 chip, already soldered into the DELL AC Power adapter."

    http://www.laptop-junction.com/toast/content/inside-dell-ac-power-adapter-mystery-revealed
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2014-02-23 21:36
    Some hacks destroy more than they create. It seems to me that you are headed in that direction. Just try to find a 12VDC adapter that would be properly recognized by the Dell and leave the batteries in place. Or try the alternative that Bob Lawrence mentions.

    There are just so many ways to get this wrong and have the BIOS lock you out.

    BTW, there are hacks that do add something significant. This just isn't one of them. It might be easier to move on to an early EEEpc with solid-state disk storage and Linux. The power supply is a simple wallwart. You might locate one with a broken screen for very cheap.
  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2014-02-24 05:38
    The BIOS is not going to lock him out unless he trys to flash it .

    messing with the BRICKS chips is not going to make a PC just give up and not work. worse that can happen is that the clone cant worrk and his system is not gonna like the home brew charger .


    Bomber what PC specs do you Need .....
    BTW a VERY easy way to get a off the rack 12V computer is to use a 90 W DC DC boost on a macmini s they are X86 and take 19 ish Volts to run . shove Any OS on it and volla sweet mini computer and it is still smaller then a micro ATX total system .
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2014-02-24 06:36
    Well, we seem to have differing opinions of what a laptop's BIOS might include. I presume that the Dell has a power management scheme included WITH some sort of handshaking that uses a Dallas Semi 1=wire chip to verify the power supply is acceptible.

    If that is the case, BIOS will just continue to reject anything that doesn't conform. The six wire input is part of making the charger unique. You have to sort out which wires do what as well.
  • bomberbomber Posts: 297
    edited 2014-02-24 08:49
    Peter, In terms of specs, i will be loading Ubuntu on when I get the hardware issues resolved, and I will be running some of my own python programs on there (they will be using the Kinect and preforming some pretty intense calculations). In terms of peripherals I will be connecting the Kinect, the Prop controlling the hardware, a wireless reciever for an Xbox remote, and possibly a second prop for some additional hardware. The computer will need wifi (python program will be relaying data through a socket to my main server) and bluetooth (to communicate with a smaller robot that Eddie my be able to deploy). The current laptop I am hoping to get onto Eddie is a Dell Inspiron E1705, and it has 2GB DDR2 memory, an Intel core Duo processor running at 1.73 Ghz, built-in Bluetooth, Wifi, Raedon graphics, and a 200gb Sata 3gb/s hard drive.

    A lot of the options you guys have mentioned are preferable to what I am doing now, and I would be doing those if I had access to any sort of budget. I'm 13 years old and I'm not in the wealthiest of families, so you can see why I wouldn't be able to just buy a micro ATX system or mac mini just for use on Eddie. I got the laptop from a friend who was going to throw it out and I was able to get Eddie only because of the prize money from the MicroMedic contest.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2014-02-25 01:18
    Well, if you live near Berkeley, California.. you might visit Urban Ore to see if they have an old power supply sitting on a shelf for $1. You might get lucky.

    Another cheap alternative is to borrow a power supply that does properly work and to download the 512 byte code on the 1-wire chip.

    A BasicStamp or a Propeller can easily download the 1-wire chip data, and can write a new one with the same. After than, any power supply that you create will work if the 1-wire chip is included where it belongs.

    Of course, the trick is to get that 512 byte code. Dell seems to want you to buy a power supply only from them. Others may claim to work (due to the right voltages) but fail.
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