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Thread: Need advice on battery replacement for 286 motherboard

  1. #1

    Default Need advice on battery replacement for 286 motherboard

    Trying to figure a way to get a new batter in this pesky 286 motherboard, any ideas ?




  2. #2

    Default

    See the 4 pin header footprint labeled "battery'? Populate it and use it.

  3. #3

    Default

    Also cut the old one out before it leaks.

    I like to stick my plug-in battery packs to the outside back of the computer (sometimes requiring lengthening the wires), so they if they eventually leak someday they'll just mess up some paint instead of destroying the mobo.
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): TRS-80 Model II,12,16,6000, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  4. #4

    Default

    Do I have to weld a 4 pin adapter in place where it says battery ?

  5. #5
    Join Date
    May 2006
    Location
    Melbourne, Australia
    Posts
    6,669

    Default

    The 'CMOS battery replacement' query comes up often. The web page at [here] is what I created to answer many related questions. As an example, on some motherboards, to switch to use of the 4-pin battery connector, sometimes a jumper needs to be changed.

  6. #6

    Default

    Quote Originally Posted by modem7 View Post
    The 'CMOS battery replacement' query comes up often. The web page at [here] is what I created to answer many related questions. As an example, on some motherboards, to switch to use of the 4-pin battery connector, sometimes a jumper needs to be changed.
    This is all I could find on my motherboard but it looks like the external battery jumper is incorrect.
    https://stason.org/TULARC/pc/motherb...MODEL-195.html

    As you can see my motherboard doesn't have jumper 20 (external battery)


  7. #7
    Join Date
    May 2006
    Location
    Melbourne, Australia
    Posts
    6,669

    Default

    Quote Originally Posted by DennisDC View Post
    This is all I could find on my motherboard but it looks like the external battery jumper is incorrect.
    https://stason.org/TULARC/pc/motherb...MODEL-195.html
    The motherboard on TH99 that you pointed is a different motherboard.

    Quote Originally Posted by DennisDC View Post
    As you can see my motherboard doesn't have jumper 20 (external battery)
    For your motherboard, the 4-pin Berg connector for an 'external' battery is missing. Per post #2, you could solder a 4-pin inline Berg connector on.

    Maybe the nearby 6-pin Berg connector is there for an external battery. If it is, you would have to work out its pin-out (what pin does what), find an appropriate mating connector, etc.

    Per post #3, you could buy another 3.6 volt NiMH battery, locate it away from the motherboard, soldering wires between the battery and the motherboard.

  8. #8

    Default

    Run insulated solid single strand wire to a 2 AA battery pack and use alkaline batteries. Trace down the circuit on the positive lead. There will be a diode and a resistor. remove the resistor ( this is to charge the battery ). You don't want to charge non-rechargeable batteries.
    Place the battery holder in a zip lock bag with about 2/3 of the zip closed so that the bag can breath and place so that what is inside can drop out. This bag and battery cells should be at the lowest point of the machine. Attach a piece of paper and write down the settings of the CMOS and tape it to the inside of the computer, above the bag. About every 3 to 4 years, replace the cells, even if they don't need it. Put a tag on the outside of the computer to remind you to replace the cells by this date or remove them if it is being stored.
    You might ask why not use multi-stranded wire. It is because the electrolyte used in alkaline ( and NiCad ) cells will wick several feet along the wire and damage the circuit it is attached to. Single strand wire slows the creep of the alkaline electrolyte better than multi-strand that has voids.
    It is all at the bottom of the case to get a little help from gravity.
    If your computer has a NiCad in it now, replace it now, don't wait.
    Enjoy the long life of your computer.
    Dwight

  9. #9

    Default

    Another thing to note, too:

    That NiMH battery is a rechargeable, so the board is probably going to be applying charging power to your replacement pack when the machine is on. If your external battery header is not isolated from this through a diode on the board, you'll want to add such a diode to the positive wire of your battery pack, if you are installing a non-rechargeable one.
    -- Lee
    If you get super-bored, try muh crappy YouTube channel: Old Computer Fun!
    Looking to Buy/Trade For (non-working is fine): TRS-80 Model II,12,16,6000, Mac IIci hard drive sled and one bottom rubber foot, Hercules card + mono monitor (preferably IBM 5151), Multisync VGA CRTs, 040 or 601 card for Mac IIci, Decent NuBus video card, Commodore PC(286+), PC-era Tandy stuff, Aesthetic Old Serial Terminals, Amiga 2000 or 3000UX

  10. #10

    Default

    To the best of my knowledge, 4 pin external battery headers never apply charging current. They are designed to be used with primaries only

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