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Charging batteries

Former Member

I want to first say that I am very inexperienced with electronics, I know the basics but that's about it.

 

I'm wondering if there's any way to charge a laptop/tablet battery with an external USB charger? Specifically an EasyAcc PB18000. It's got a 2.1A and a 1A USB socket, I believe they can both be used at the same time for a total of 3A. The laptop charger runs at 19.5V, 2A. Apparently it's possible to step 5V up to 20V, with a loss in current to 1/4 (I'm aware of V=IR / Ohms law). I've got a couple of questions about this though.

 

  1. When charging a tablet battery (Sony Vaio Tap 11) is it more important that the voltage matches that of the charger, or that the current does?
  2. Will it damage the battery if either of them don't match?
  3. How exactly would I go about setting this up, would I need to modify the external battery?

 

Thanks in advance, I hope this is the right place for advice!

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  • 0

    Hi Oscar, It will be impossible to charge a laptop battery through the USB ports. There are devices called regulators between the battery and the USB that are one way. You will not be able to get voltage to flow from the USB back into the battery. The only real way to charge a laptop battery is through the normal charge and power jacks. In most cases thia can be done with an AC adapter or with a 12 volt adapter. Also the circuitry that mosifies the charging of the battery is important to keep it from overheating and catching fire.

    John

  • 0 in reply to jw0752

    Sorry, I wasn't clear enough. I want to use the USB ports on the charger to charge the laptop, not charge the laptop via USB.

  • 0 in reply to Former Member
    1. When charging a tablet battery (Sony Vaio Tap 11) is it more important that the voltage matches that of the charger, or that the current does?
    2. Will it damage the battery if either of them don't match?
    3. How exactly would I go about setting this up, would I need to modify the external battery?

    1. Short answer: you'll have to be able to provide both the voltage and the current that the stock charger gives. Longer: If you provide a voltage that's too low your battery charger will not start, or will not be able to fully charge. If you can't supply the current, either your supply will fry, or the voltage will sag so much that you're left with the problem of a low voltage

    2. The manufacturer will say it does. As long as you don't know the details of how the charging circuit works, you can't immediately tell from the outside

    3. If I were you I'd first test with a lab supply to see what currents are drawn, and what happens at other voltages than 19V. Please do remember that if your laptop battery is dead you'd need 19.5V×2A=39W. 5V×3A=15W, so probably you won't be able to step up AND get enough power to charge a dead battery. If you don't have a power supply, please do monitor the output voltage with a multimeter, and keep your finger on the charger to stop if it overheats.

  • 0 in reply to Former Member

    Same difference and same answer

     

    Yes you can

     

    The 4-5 v out of the USB will be in need stepped up as ugh as 20 volts

    If that needs 2 amps then you will need 8 and out of the USB going to the inventor

     

    This is far more than USB port can handle even for two ports

     

    Sent from my iPhone

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