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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!

  • 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

    It is possible to boost the Voltage to a specific charging voltage of the battery at a compromise with current but, The charging will be severely compromised. What do you have in mind when you say charging the laptop battery, I usually use the cells of the battery and charge them using some Standard cheep Li-ion charging modules.

     

    Further, the Battery pack has an inbuilt circuit that has cells connected in series for maximum voltage needed for the Motherboard/LCD as well as it charges individual cells in parallel. I will agree with John Wiltrout charging the batteries using USB But, if you are up to the challenge, You can hack the battery pack and connect all 3 cells in parallel, then you can add 2 wires from the battery pack to the charging module's something like these 1A LI ION Lithium Battery Charging Module Charging Board Charger CC CV Micro USB | eBay , and bingo, you have a usb chargeable battery pack.

     

    NOTE, Because you have 3 batteries connected in parallel, you can expect the batterypack to take approx 24+ Hours to fully charge image via USB, if you have connected to a 1A charger Approx.

     

    Regards,

    GurI

  • 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