Observation About Charging the A1

Discussion in 'Lenovo IdeaPad A1' started by ChrisB, Jan 10, 2012.

  1. ChrisB

    ChrisB Member

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    Hi all. Just wanted to pass along a something I noticed about the A1 the other day by accident. This may explain why some folks see painfully slow charging times.

    So, when charging the A1 the other night, I plugged it into a power brick I have that has a USB charger port on it instead of the 120V plug that came with the A1. I had my iPhone plugged into another USB port on the same power brick. A few seconds after I plugged in the A1, my iPhone started cycling between charging and batter about once every few seconds (and letting out an annoying beep every time it did). This continued indefinitely until I unplugged my iPhone out of concern.

    After thinking about the situation, I realized that what was happening to the iPhone was the USB power converter in the brick was getting overdrawn and tripping the overcurrent protection. After it tripped, the overcurrent circuit would recent and it would start charging for a second and the would flip again.

    That got me wondering. I looked at the power brick, and is rated for .5A @ 5v, the USB standard powered port.

    Then, I looked at the power output on the A1 120V charger brick. Sure enough, it is rated at 1.5A @ 5V, 3x the "standard" current for USB. The A1 must be configured to draw more than 0.5A for standard USB, and it was tripping the inadequate circuit on the power brick I have.

    So, if you are charging your A1 off a laptop (which likely only supplies 0.5A), or off a power brick that is < 1.5A, the charging time on your A1 is going to be significantly longer (maybe 3x). Your best option is to use the 120V adapter that came with the device, or a power brick that is at least the same current (1.5A).

    I wonder if the A1 can detect when it is plugged into a computer and limit its current draw to 0.5A in that case. If not, I could see it potentially overdrawing some computer's USB ports, or tripping their current protection.

    Just thought I would pass this along....
     
  2. janner43

    janner43 Member

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    Thanks for making the observation :)

    Actually, here is the technical bit about chargers...

    The voltage & the amperage are both crucial. So, if a device requires 5v and 500ma, you can safely plug it into a charger capable of 5v & 1.5a because it will only draw 500ma :)

    If a device (eg the A1) requires 5v & 1.5a to charge, then you might damage a wall charger which is only capable of 5v & 500ma.

    You are extremely unlikely (like it will never happen) to damage a pc usb port, however, because of the robust size of the power supply in a typical pc. Your A1 will charge, but only at 5-8% per hour, rather than the supplied charger rate of 25% per hour :)
     
  3. clonedr

    clonedr Junior Member

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    If you are having battery charging issue I found that Walmart has 2.1 amp dual USB wall charger by on for 9.98us it puts out 5 volts at 2.1 amps and charges my ideapad at 10% to 100% in 3 hours. :) you have supply ur own USB cable.
     

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