battery charge on laptop decreases on 12volt

Discussion in 'Computers' started by Welsh girl, Feb 4, 2013.

  1. Welsh girl

    Welsh girl Funster Life Member

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    After receiving very helpful advice on another problem I wanted to also find out about this.... when we are not on hookup and using the 12 volt to supply and charge my laptop, I noticed while using my laptop the little charging icon on the bottom right of my laptop said "charging and plugged in 64%" but the percentage kept dropping even when being charged.
    Am I using more power than I am putting in while using the 12volt plug.
    If I kept using the laptop I could run out of power?
    It doesn't do this on electric it charges fully when on electric.
     
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  2. aba

    aba

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    some 12volt chargers will only put out a small amperage and looking at what you said it is charging but at a rate lower than the laptop uses.
    you may find that if the laptop is in standby or turned off it will charge it although slower than the mains charger.
     
  3. rainbow chasers

    rainbow chasers Read Only Funster

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    As Aba says, turn off to charge. Most laptops require 19v to function, so you will be using more than you are replacing. You can use through an inverter if you have a tired battery.
     
  4. GJH

    GJH Funster Life Member

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    I think the previous replies are on the right lines. You need a 12v charger which will deliver the same output ratings as the mains charger.
     
  5. Gromett

    Gromett Funster

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    I will second the previous responses. I have an expensive charger that can charge and power the laptop but it gets incredibly hot and makes funny noises after a bit. What I do is ensure the laptop is fully charged before powering it up. This way the charger only has to maintain the full charge not fill it up and power it at the same time.
     
  6. pappajohn

    pappajohn Funster Life Member

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    in a similar vein, my Kindle fire will not charge by either USB, mains adaptor or 12v fag lighter adaptor if it's in use.

    all the various chargers are doing is maintaining the present battery charge.
     
  7. Addie

    Addie Trader - Motorhome Wifi

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    I've been using 12v laptop chargers for 10 years or more, firstly as a sales rep on the road and later as a motorhomer.

    A lot of 'cheaper' 12v laptop chargers supply enough voltage for the laptop to sense a power supply is present, but not enough to charge a laptop. Ideally if you have a multi-voltage one, you need a 130W variant.

    Lots of the 90W versions I've tried have pathetically thin cable and perform exactly as you have described here.
     
  8. Johno

    Johno Read Only Funster

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    I'm not an expert but I think most laptop internal batteries are around 20 volts so possibly when connected to 12 volts you may actually be putting in a reverse charge from the 20 volt laptop battery to the 12 volt leisure battery which would account for your drop in charge on the laptop.

    John.
     
  9. Gromett

    Gromett Funster

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    Not so, the chargers we are on about step up the 12v to the required voltage of the laptop. Sadly they are underpowered ie they can't supply enough amps at said voltage.
     
  10. Johno

    Johno Read Only Funster

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    Hi Trish-n-Tez

    If you google "Motorhome WiFi" and look on their accessories section they sell a laptop charger which works on 12 volts and gives a range of output voltages from 15 volts to 25 volts, I guess it must be some type of DC to DC convertor.
    Hope this helps.

    John:thumb:
     
  11. Johno

    Johno Read Only Funster

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    Apologies I was under the impression from the original post that they were connecting directly to the 12 volts:Doh:and not using a charger.

    John
     
  12. hilldweller

    hilldweller Funster Life Member

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    Our MH has a good old fashioned pointer ammeter. It's fascinating to be using the laptop and watch the ammeter, every time I hear the HD being accessed the needle kicks across a few amps. I've even seen this on 240V using a current monitor adaptor. HDs eat power.

    Have you see in the news, the all singing all dancing new Yank plastic airliner is grounded because it's Lithium batteries are catching fire. I deliberately provoked a failing e-bike battery by shorting out some cells, first attempt vaporised some wire, second attempt with a proper job short the cells swelled up and to my surprise started spitting flames.

    Don't mistreat Lithium batteries.

    Picture of a Boeing one...
     

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  13. Gromett

    Gromett Funster

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    The "beauty" of Lithium batteries in fail mode is that they produce their own oxidant. They can burn in a vacuum and boy do they burn.. Did one on an old laptop battery a couple of years ago after reading about it. Wow, massive flare came out of it.
     
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