Increasing life of laptop battery

Discussion in 'The Projects Forum' started by hyperNinetynine, Aug 20, 2011.

  1. hyperNinetynine

    Thread Starter New Member

    Aug 20, 2011
    4
    0
    so i passes a few articles saying how you could replace your laptop battery pack if you got the same kind of batteries used in the battery pack. So i had the idea of increasing how many batteries are parallel in the pack and making an extension to the pack (probably with hobbie supplies or something.. nothing too fancy....).

    Before i ask questions the battery packs stats are:
    +10.8v | 44mAh | 47Wh
    6batteries; 2 parallel/ in a series of 3
    so = six 3.6v 22mAh batteries

    Alright, so i have 2 questions:

    #1

    (from my volt meter; the batteries that came in are a little over charged. bought 3.7v and came in with print saying this. voltmeter says 3.84v.

    3.84 x 3 = 11.52... i have resistors i'll be throwing in to get it down to 10.8. i consider myself still new-ish to electronics but seems common sense to me that going up or down(even just a little) in voltage is really bad for the device, since the voltage labeled on the pack was "10.8" and not "10ish" so anyway the Q:
    How bad is it to stray from the exact voltage that the original battery was ???

    #2

    i'm going from 2 batteries parallel to 4. doubling mAh from 4400 to 8800.

    This does nothing but make the batteries all together last longer correct?
    i beleived this to be true but read something a few days ago that gave me the impression that this would possibly be bad for the laptop.

    I usually dont do anything without being 100% sure i'm doing it correctly. and even tho i'm doing this for my 300 dollar netbook with already a battery life of about 8 hours. its still 300 dollars that i dont wanna throw away. and hell i'm greedy lol. if it works i'm gonna add more batteries. i want a 24hour netbook. =D
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,795
    951
    There are several types of lithium battery. If you have the 3.6 volt type and try to mix it with the 3.7 volt type, trouble will result. Maybe even damage to the equipment,up to and including fire.

    DO NOT MIX battery types.

    Do not add a resistor to the battery to lower voltage. Resistors do not function in this fashion. The device using the battery will have VOLTAGE regulators inside and will not care if the voltage is 11.5 or 10.8 coming from the battery.

    If you want to increase the capacity of the pack you must use the same type of battery. WARNING: charging lithium batteries is dangerous and special circuitry is very often included in the battery packs for detection of temperature and state of charge. bypassing these or defeating them can result in dangerous outcomes, including explosion of the battery or fire. Youtube 'lithium battery dangers' and view some of the situations and demonstrations.
     
    hyperNinetynine likes this.
  3. hyperNinetynine

    Thread Starter New Member

    Aug 20, 2011
    4
    0
    oh and i forgot to mention both batteries are lith-ion

    thanks alot
     
  4. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    Should we assume you meant 4.4AH and not 44mAH and 2.2AH and not 22mAH? Because at those ratings you might be able to light a few LED's but no way will you be able to turn your computer on.

    As Kermit2 said, do not uses resistors.

    Well, if you want a 24hr netbook, use the adapter. You will void the warranty if you make this alteration.

    You must insure that all batteries are NEW and have the exact same Voltage rating(not just what the present terminal voltage is) and current rating. It would be preferable that the batteries are all from the same manufacturer as well. If the rated voltages and AH ratings are different your netbook might run longer before needing a charge, but your batteries will die a swift death.
    And when you have just one battery failing, it will bring down all the rest that much faster. Your best bet would be to buy a second battery pack.

    The big question I have for you is: Where do you plan on being that you would require 24hrs of netbook time? I hope you are not planning a weekend camping trip and plan on staring at the computer as apposed to taking part in the winderness experience.


    You want to increase your netbook battery time!

    Turn down the brightness of your monitor.
    Don't use regular screen savers, use one that literally turns the power to the monitor off.
    Setup sleep mode to activate sooner
    Reduce the extravagant animations for OS operations
    Turn off OS sound schemes
     
    Last edited: Aug 20, 2011
  5. BrainFog

    Member

    Jan 24, 2011
    122
    4
    I am amazed that 8 hours is not enough. I have been pondering a similar idea for my netbook which only lasts for about 2 and a half hours. I am also new to electronics and I am amazed at how often electronics seem to defy common sense or make us rewrite what we thought we knew.

    The idea I am thinking of, for my project, is rather than modifying the laptop battery itself was to make a battery pack that would then connect into the laptop the same as the charger. I liked this idea as it would not be difficult to produce, exactly, the 20v my laptop charger produces with a voltage regulator. Another advantage is that you could use any kind of battery you want standard AA, lithium ions or even lead acid batteries. Another thing I intended on doing was adding a device that would cut power once the battery voltage reached a critical level which would simply cause the laptop to use its build in battery.

    I am interested to see how your projects turns out, make sure you keep us informed.
     
  6. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    8hrs with a new netbook is probably the mfg. hype as it depends heavily on the usage of the netbook. If you are getting 8hrs from general use just waite a year and you'll be lucky to get 6hrs, another year and you might get 5hrs or 4hrs.

    BrainFog,
    There are two issues I see with your idea that you might take into consideration.
    1) A lot of notebooks, netbooks, notepads, laptops...etc. these days have circuitry that sense the power adaptor and make sure it meets a certain criteria before the laptop will accept it. It's sort of like trying to charge an iPhone with a generic charger. This could kill your idea in a heartbeat.

    2)If the notebook does accept the power source you provide and the battery pack is in the computer, it will use it's energy to charge the battery pack and run your computer. Maybe this is not a bad think if the pack is already fully charged. If the battery pack is removed, then you would not have this issue.

    I have had a laptop without a battery pack for over a year as I always happen to be somewhere I can plug it in to. I have even used junkyard SLA 12V batteries and an inverter to run it and then turn around and charge the
    junkyard battery with a 60W solar array. I'm considering building a DC-to-DC Step-Up converter to bring the laptop source up to 14V - 15v which is required by my laptop. My laptop is much older and does not suffer from the input supply checks that the new portable computers might. It would be light-years more efficient than using an inverter (12VDC - 120VAC - 19VDC, 3.3A)
     
    Last edited: Aug 20, 2011
  7. wayneh

    Expert

    Sep 9, 2010
    12,150
    3,058
    It's no issue to the laptop - it won't "know" the difference at the hardware level. Your power management system software might be confused about battery status, remaining time and so forth. But you do need to have each battery pack be a matched set as you've been warned. I've read that even within the same manufacturer's output, they'll pick and choose individual cells to optimize the pack. It doesn't even matter which type you use (3.6 versus 3.7) as long as they're all the same.

    Is it possible to swap battery packs without a total reboot? I'd just carry more packs for more time, but I guess that doesn't work so well if you can't swap smoothly.
     
  8. BrainFog

    Member

    Jan 24, 2011
    122
    4
    I am concerned that I am hijacking this topic with my questions but I suppose it is ok as the purpose of this website is to share knowledge. If the OP has a problem feel free to tell me.

    For me the external battery would most likely only be used when the laptop has a fully charged battery so this is no issue for me. The netbook is about 3 years old and is based on the msi wind.

    This input supply check is interesting, I have never heard of it and I found nothing using google. Could you tell me a bit more about it and how it works and what it looks for?

    I did strongly consider using two 7ah AGMs (a type of sealed lead acid battery) in series and then use something like an lm317 to drop the voltage to 20v, allowing noise free regulation; until I thought about what they would be like to lug around.

    One thing that may be relevant is that I have read that it is possible to run some switch mode power supplies using DC instead of mains AC. this would most likely only work with 220v DC and could potentially be an interesting way of using the charger to power the laptop from a battery without first converting it to AC.
     
  9. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    Your discussion is somewhat relevant to the OP's "alternative supply" objectives, and we haven't heard anything recently from him regarding his own project for us to offer more assistance, so in a way it seem like a hijack, but we will have to let the Moderators Mod this and apologize now for the diversion.

    Good.

    This "supply check" as I have called it may be nothing more than what wayneh spoke about earlier, but I have had some laptop supplies not want to work with other laptops, despite adequate Voltage and current.

    These days, with the tiny netbooks, I can understand, the batteries are as large and weigh more then the netbook. My objective is to utilize the sun for my computer needs and other appliances.

    Where does one find a 220V DC source. I think the Step-up regulator will be fine or even the step-down from 24V to 20V would be efficient. As long as I have access to usable junkyard batteries I a happy camper.
     
  10. BrainFog

    Member

    Jan 24, 2011
    122
    4
    My main objective would be to experiment and give in to curiosity.

    Is it possible that the chargers simply had opposite output polarities so people could not interchange them?

    Finding this on ebay has all but put an end to my battery pack: http://www.ebay.co.uk/itm/Battery-M...cessories_LaptopBatteries&hash=item4aa9df6bab my current battery is 2200mah and for only £30 I could upgrade to 7200mah. Turns out my battery is currently down on capacity so it would be 4 fold increase in battery life.

    Still I may try the battery pack idea just because I can.
     
  11. hyperNinetynine

    Thread Starter New Member

    Aug 20, 2011
    4
    0
    for an update..

    yeah forgot the "00's" in 44mAh

    not worried because i'm doing this just for the sake of experience and notebooks arent that expensive... and hell it would be cool to do =D


    yeah, so, after i finished wiring all the batteries together i think i got some of them too hot. some of them lost voltage completely cuz i couldnt seem to soder the positive side of the batteries. just wouldnt stick.. FINALLY figured out a way and by the time i got them all together the 12 batteries ran at full charge for 3hours and 30 mins. vs the new battery that i ordered that has a 4800mAh rating for 8 hours.. not to mention i just seen a youtube video of lithion battery exploding so i would attempt to soder then throw it in the freezer for a few mins.. when i checked on 2 of them they lost charge almost completely. =( so i'm about to order a bunch of new batteries...



    initially: international plane ride.. tho the weekend camping trip will DEFINATLY stay in the back of my mind when i finally get this working lol. i've had my share of "the wilderness"

    i'm actually running arch linux w/ openbox.. thats probably how i'm pulling out 8 hours in the first place lol =D



    OK NEW QUESTION: does the small circuit board that was in the battery pack regulate any of this that i'm trying to manipulate???

    for instance.. i'm thinking about re-doing this by buying ONE 10.8v battery with a huge mAh rating on it. does anyone know what the small circuit board in the battery pack does?????
     
  12. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    It protects those "explosive" batteries from overheating and overcharging.

    I hope the airline security will let your contraption through the gate....or am I hoping otherwise!?!?
     
  13. hyperNinetynine

    Thread Starter New Member

    Aug 20, 2011
    4
    0
    yeah thats what i'm hoping lol this thing looks kindof sketchy.
     
Loading...