Laptop switching to battery while connected to AC adapter

Laptop switching to battery power while turned on with AC adaptor
Model: Toshiba Satellite A70-TS100E
I was wondering if you could help me in identifying the cause of this problem.
While turned on, the laptop will switch to battery power even if connected with the AC adaptor (sometimes during boot-up, or after a while) until the battery drains out, he then goes to hibernation (the battery light is off). If no battery in the laptop, it will shut down, and the AC light will blink very fast. The battery (li-ion) will only charge up to 10%, where it then jumps right up to 100%, and will discharge from 100% to 90% then jump to 0%, go to hibernation, and fails to complete the process, shutting down. The adaptor makes a small “camera flash charging” sound, stabilizing at 19v. When charging, it repeatedly makes the “charging sound” Faulty AC adaptor? Or Faulty battery? Or Both?

I think you might have a few different problems at the same time.
First problem: the laptop switches to battery power even with connected AC adapter. Most likely you have a faulty power jack. It’s either broken or loose. It’s a known issue with Satellite A70/A75 laptops and you can fix it by replacing/resoldering the power jack or relocating it outside laptop case.
It also could be a problem with the power cord. Find a multimeter and check the AC adapter. See if the power cuts off when you jiggle the power cord. If it does, replace the adapter.
Second problem: the battery will discharge from 100% to 90% and then jump to 0%. It sounds like a bad battery.

53 Responses

  1. Laptop Freak

    Ming,
    So the “AC plugged in” message appears only for a moment when you plug the power adapter, then it switches to “Running on batteries” and you cannot switch it back to AC if you wiggle the power plug or move the cord, right? Most likely there it’s just a power jack problem and you’ll have to resolder it. But there is a small possibility that something is wrong with the AC adapter.
    I would take a look at the power jack before ordering a new AC adapter.

  2. Hello! I have an hp dv4305. I am having a problem with my power jack. My husband was holding the laptop, and it slid off onto his legs and bumped the ac plug. Now it will only charge if we put pressure on it. I guess I really need to know how to check it. Thanks, Kim

  3. I have a Sony Vaio (model PCG-V505DX). The problem is that when I plug in the AC adapter, it powers the laptop intermittently. Windows shows messages that switch between “AC plugged in” and “Running on batteries”, and the messages alternate very fast. I tried adjusting the connector and the wires on the AC adapter but there was no improvement. I checked the output of the AC adapter which shows around 15.6V rather than the 16V indicated on the label. I assume that is probably OK. So does that leave the power jack as the potential problem? I appreciate any feedback on this issue. Thanks.

  4. Laptop Freak

    Jean,
    You can replace the power jack in three “easy” :P steps:
    1. Find a new power jack. You can find it really cheap here, if you search by P25 power jack
    2. Remove the motherboard from the laptop
    3. Replace the jack
    I hope it helps.

  5. I have a Toshiba Satellite P25-S5263 and I need to replace the power jack on it, is there some kind of easy tutorial which shows what to do ? And also what does it mean “to modify the power adapter to the 2.5mm center pin” Will I have to modify this 3.0mm DC power jack(which I’m going to purchase on ebay) for it to work with my laptop?

    I’d really appreciate any help I can get, Thanks =)

  6. Scott Fisher

    Freak: Thanks for the info, I decided not to purchase tools and attempt myself, I tore it down and took to my local TV/Appl. Repair Guru, He has made many laptop repairs and said only $15-$20 bucks, WHAT A DEAL! My hats off to you Elec. Repair Geeks and Thanks for the Web Site !! :)

  7. Laptop Freak

    Josiah,
    It’s hard to say without testing the laptop with a known good AC adapter. Yes, it could be just a bad AC adapter but it also could be a problem with the system board. I would probably replace the AC adapter first, they are not very expensive.

  8. Laptop Freak

    Scott Fisher,
    I use a Weller digital soldering station (50W unit, temp range 350 °F – 850 °F) and for soldering/resoldering laptop power jacks I set the temperature to 850F. Works perfectly fine for me. If the old power jack is not broken, you still can use it. Clean the power jack contacts and coat them with a new layer of solder before you put the jack back on the motherboard. Also clean and coat the contacts on the motherboard.

  9. Hi. I am having a similar battery problem with my Dell Inspiron 1150. Here’s a typical scenario…

    1)AC adapter is plugged into laptop.
    2)The laptop boots up fine and works normal.
    3)Suddenly, the laptop switches from AC plug power to battery power.
    4)The battery slowly drains and eventually dies 1-2 hours later (depending on charge).

    When the laptop is working normally (working with the AC adapter), I’ve tried jiggling where the AC adapter plugs into the computer. It doesn’t seem to make the computer hop to battery power.

    I can even unplug the AC adapter, allow the computer to switch to battery power, and plug it back in and watch it switch flawlessly back to AC power. But then, randomly, the laptop will switch to battery power and eventually shut down. The only workaround I’ve found is to shut down, unplug and replug the Ac adapter, wait, and restart. Then the laptop works fine for an undetermined amount of time.

    Any ideas? I was thinking either the AC adapter is dying or something with the BIOS. THanks for your time.

  10. Scott Fisher

    power jack replacement on HP Pavillion zt1170

    I have a new power jack in hand and ready to tear into my laptop, What soldering tools should I get? I see small 25watt pens & cordless cold soldering tools? what is too hot? and solder type is best?

    I assume relocateing the jack outside is the BEST way to prevent this from happening again? could I use a small chunk of drop cord wire for this? what type of wire and gauge would be best? and are there detailed instruction for the zt1170 or use the HP Service media Library link
    http://h20181.www2.hp.com/plmcontent/NACSC/SML/

    Is it best to use the new jack or is it possible the old jack can just be re-soldered?

    THANKS -Scott

    my old soldering gun is one of those old Colt 45 looking beast which I’m guessing is WAY to hot for what I need, now what (haha) :)

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