Using wrong adaptor with same V but wrong amps with my laptop


Shortly: the battery should not have been damaged at all. Continue using your new adapter.

First, current mismatch is not as dangerous as a voltage mismatch because internal power supply in the laptop is sensitive to overvoltage, but when external adapter could not provide current neccessary for laptop's operation it will just turn off and drain battery instead as if adapter was unplugged.

Second, there are many levels of conversion and protection between your power supply and the battery cells (by writing "cells" I mean the thing in the battery unit that gets charged). There is internal protection in the battery that continously monitors voltage, current and temperature of the cells and handles overcurrent, overvoltage and many more erroneous conditions. Also, battery don't get charged straight from the adapter: there is at least one chip, the charge controller which not only internally stabilizes it's output voltage but also has it's own input protection. So if everything had worked and keeps worked, your laptop is very unlikely to be damaged.

Now you cannot work without adapter plugged in because it's output current was only to power the laptop and not charge the battery. Moreover, in peaks of current consumed by laptop it even drained your battery because adapter itself could not meet even minimal current requirement.


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A software junkie for sure, with a particular weakness for open source applications - if there's a decent open source alternative I'll go for it!

Updated on September 17, 2022


  • wonea
    wonea 5 months

    I have a Toshiba Satellite A200 1-GH. My sister's old laptop was also a Toshiba. The adaptors were mixed somehow, and I've been using the wrong adaptor for a very long time. I've realized this when my computer could not work without the adaptor plugged in. When I checked out the voltage-amps values, the values on my computer were 19V-4.7A, the values on the adaptor were 19V-3.42A.

    I bought a new adaptor corresponding to the values written under the computer immediately, but I was wondering if the battery should also be replaced? If so, what happened to the battery technically that made it useless any more?

    • Apache
      Apache over 12 years
      If it works (the battery also), guess there is nothing wrong with it. You've been lucky and that's all. :)