Tecra M4 Battery Swap Question

Discussion in 'Toshiba' started by Gautam, Jun 5, 2006.

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  1. Namssorg

    Namssorg Industrial Designer

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    I have a Tecra M4 that came with a battery with part# pa3191u-4brs.

    I also have a spare battery from an old laptop (portage) with part # pa3191u-3brs. The only difference between the two I can tell is the Milliamps. Mine has 3700 and the old one has 3400. It fits in my Tecra M4- and powers it just fine. Aside from a little less battery life, is there anything I should be worried about if I use this battery as a spare for my M4?
     
  2. poetdante

    poetdante Scribbler - Standard Member Senior Member

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    I wouldn't use it. it could mess up your tablet
     
  3. Barry J. Doyle

    Barry J. Doyle Scribbler - Standard Member Senior Member

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    Ugh, I agree with Dante on that one. I would call Toshiba support to verify that what your doing won't hurt anything.
     
  4. greenzkool

    greenzkool Pen Pal - Newbie

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    It should be fine, the 4brs replaced the 3brs (you can read this on toshibas website). as long as the batteries are the same voltage, which they should be, it fine. If you are really worried you can ask toshiba.

     
  5. nfwolfpryde

    nfwolfpryde Scribbler - Standard Member

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    Are you kidding? As long as it's the same voltage it's fine? WAY WRONG. Current (amps) is just as important as voltage!

    Think of it like this. Electricity is like fluid in a hydrolic line... say for your brakes. When you press on the brake pedal, you apply pressure to the system, pushing the fluid along to do work. That's voltage, the "pushing." Now, there's only so much fluid that's supposed to be in the line. That's why in fluid systems like oil, washer fluid, etc, there's a "fill line." Current is like the "amount" of fluid. So what happens if you have too much fluid (i.e. current) in the system?

    The system bursts.
     
  6. Namssorg

    Namssorg Industrial Designer

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    I should also mention that I am currently undervolting the tablet, if that makes a difference.

    Nwolfpryde, are you sure? The measurement is in Milliamp Hours (mAh). I'm not sure how different that is from the actual mA rating (Which measures the current the battery is CAPABLE of delivering.. not what it will always) I don't think using the 'lesser' battery will blow my system out-- if anything it won't work, right?

    It's fairly common to replace batteries in other devices (cell phones, gaming systems) with higher mAh rated batteries to get a longer battery life. In fact those batteries are even sold in stores. Those batteries have the same voltage, but a higher mAh. So I'm wondering if it really is harmful to go lower. Normally a model that ships with a higher mAh battery is due to the computer using a little more power, but the manufacturer wanting to keep battery life the same.

    Here's what the two say:
    3BRS:
    DC 10.8V 4400mAh

    4BRS:
    DC 10.8V 4700mAh

    I'm going to call Toshiba and see what they say-- I'll post their reply here just for future reference to anyone else.
     
  7. Namssorg

    Namssorg Industrial Designer

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    Comment off another forum:

    A lower mAh rating won't physically damage the system. You may have a data loss problem if the battery gets really low and Windows doesn't have time to kick you into hibernation before the battery goes dead completely - it may get confused about the theoretical reserve and think there's still time.

    The other consideration is that this is an "older" battery. You do know that Li-ion batteries have a limited lifetime (< 24 months) beginning at the date of manufacture, right? So the odds that this "older" battery is going to last any amount of time at all before it flatlines forever are pretty small. You might as well start shopping around for a good price on a standard, or even an extra capacity, battery now.

    Good luck.

    Kurt
     
  8. nfwolfpryde

    nfwolfpryde Scribbler - Standard Member

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    Okay, mAH is definitely different than mA, which is what you told us before. mAH is how much the battery can hold, and a larger mAH does simply mean that it holds more charge. Check out upgrade batteries if any of you have them, all the specs except mAH will be identical (ideally...). mAH is a unite of charge, as opposed to simply mA, which is a unit of charge/time, or current.

    Charge= current x time

    Current = Charge/Time

    Current = mA
    Time = Hours
    Why they don't just put the charge on the battery instead I have no idea.


    So, since it's outputting the same voltage, and as long as it's outputting the same current, you're absolutely fine.

    But I'm guessing you've already talked to somebody else by now and have come to that same conclusion.

    As for the age, it's very true that Lithium Ion batteries lose the ability to charge themselves overtime. They eventually just degrade into other compounds (think of it like rusting, but without the iron).
     
  9. Namssorg

    Namssorg Industrial Designer

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    Okay cool, thanks for clearing that up. I'm a lot less hesitant to try it out now (Just planning on using it for long trips when my other batteries are out of juice)
     
  10. greenzkool

    greenzkool Pen Pal - Newbie

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    How did i know someone was going to post a comment like this, if you knew anything about batteries and power you would know that batteries do not have a built in current, the current is produced depending on the voltage of the battery and the impedance of the circuit in the computer. Since that impedance is not changing and the voltage is the same, the current is fine. No batery has more current than another, it all depends on the circuitry that it is running. A power source is another story. The battery is fine. They replaced the older battery with a newer one that has more life. When the batteries in your camera or phone die, do you go get the same ones that are supplied with it? no, you go get the same voltage. THE BATTERY IS FINE
    And I do know what i am talking about, I am an engineering student going through lots of electrical classes and control systems classes. I have also built robots for design classes and did all of the circuitry.


     
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