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Thread: KYD/NEE LI-ION battery problem

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    Default KYD/NEE LI-ION battery problem

    Hi all, I have a problem with one of my batteries, its for a ne-768/tk760A, It is about 3 years old now.

    After the radio is on for a short period of time, it switches itself off, the battery is fully charged, the cell appears to be good, I have dismantaled the battery and measured the voltage on the terminals on the cells,which remain at 8.1v even though the voltage at the radio terminals drops to around 1.2v when it switches itself off, I have re-solder pretty much all joints.

    I have access to a 6 times stereo microscope at work and had a good look at the circuit, some of the solder pads on the IC's looked a bit suss, so I managed to resolder them. Still no luck, I susspect that I might have Bad IC or something.

    Any ideas from the LI-ION Batter experts?
    Thanks In advance.



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    It sounds like the cell protection circuitry is stuffed. This is usually a tiny PCB which prevents overcharge, over-voltage and is a cut-off for low cell volts.

    If this PCB is damaged you can remove it and use the pack naked BUT you will have to monitor charging current and cell maximum voltage (4.2V/cell) AND minimum discharge voltage (~2.75V/cell).

    The little 'protection' PCB is actually quite clever/busy ! I have seen these PCBs for sale on the net at low cost, for example :-




    - and you could possibly get one to fit your pack. Alternatively remove the protection and watch carefully its operation, Lithium Ion packs can do nasty things such as catch fire when protection is removed. Some cheap radios/systems rely only on the cell protection to control charging operation, you will have to do the cell monitoring if the protection is removed and a 'dumb' charger is used.

    I reckon spare battery packs are also available fairly cheap on Eekbay.

  • The Following User Says Thank You to bulbous For This Useful Post:

    toyboy2131 (23-05-09)

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    Quote Originally Posted by bulbous View Post
    It sounds like the cell protection circuitry is stuffed. This is usually a tiny PCB which prevents overcharge, over-voltage and is a cut-off for low cell volts.

    If this PCB is damaged you can remove it and use the pack naked BUT you will have to monitor charging current and cell maximum voltage (4.2V/cell) AND minimum discharge voltage (~2.75V/cell).

    The little 'protection' PCB is actually quite clever/busy ! I have seen these PCBs for sale on the net at low cost, for example :-




    - and you could possibly get one to fit your pack. Alternatively remove the protection and watch carefully its operation, Lithium Ion packs can do nasty things such as catch fire when protection is removed. Some cheap radios/systems rely only on the cell protection to control charging operation, you will have to do the cell monitoring if the protection is removed and a 'dumb' charger is used.

    I reckon spare battery packs are also available fairly cheap on Eekbay.
    Thanks for that, I thought as much, I'll look into the replacement control board option, failing that I might keep the cells for later on (assuming they can be stored for periods of time) to replace the cells inside the "good" battery when they go knackard.
    Thanks
    ToyBoy

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    Lithium Ion cells will store fine - but for best life should be stored fairly well discharged with terminal voltage around 3.3V unloaded.

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