Reviving a dead Li-Ion battery

Discussion in 'DIY' started by SaSi, Jan 12, 2009.

  1. SaSi

    SaSi AK Subscriber Subscriber

    I was given a perfectly working aiwa Minidisk portable player (AM-F70). But the battery was dead. The multimeter read 0.00V after 2 hours of charging.

    I seems there is absolutely no source for the obscure battery in this deck, so I tried a trick that I never had the opportunity to test:

    Took a 12V power supply and touched the poles of the dead battery with that to trickle charge it. The actual Li-ion battery for the aiwa is rated at 3.6v.

    After the first 10-20 second revival charge, the meter read 0.5v or something. After a few more cycles, it read 2.5v.

    At that point i mounted the battery back to the player for a proper charging with the unit's charger.

    After about an hour or more it stopped charging and I tried the unit off the battery. It works. It played a complete MD of 74min and still was 3/3 charge. The specs for the unit are for 10 hours continuous play, and this is something I will test today, as soon as I find a MD with decent music in it.
  2. ozmoid

    ozmoid Lunatic Member

    Li-ion batteries have a finite life of around three years. The power loss to aging has a very slow taper at first that drops dramatically at the end of the battery's life. I'd keep looking for a replacement. :yes: YMMV.
  3. SaSi

    SaSi AK Subscriber Subscriber

    Well, without any insult intended, I really hope you are wrong (lol). That battery is certainly much older than 3 years. I think this player was bought in 2000 or 2001 - my friend bought that briefly before the Euro was introduced.

    I guess there's no way this battery can be sourced anymore. The only other solution would be using an external pack with 3xAA batteries, not something really suitable for this nice pocket player.

    I guess I will enjoy whatever life there's left in this battery.
  4. Ed in Tx

    Ed in Tx Super Member

    What you did you the Li-Ion battery sounds similar to what I have done to "fix" internally shorted NiCad batteries.. give the shorted cell a good "zap" with much higher voltage for a brief instant. This can temporarily open the conductive dendrite crystals that form internally in a NiCad that make it read 0 Volts even after a brief charge time (and near 0 Ohms with an Ohm meter too). I've saved several battery packs my zapping cells to open up internal shorts, usually just a temoporary measure though the problems usually come back since this happens mostly on aged batteries. Did not know you could do that with Li-Ion.
  5. similost

    similost Rockin and Rollin.... Subscriber

    I'd be very careful doing something like this. While yes, it can work to save a battery, or at least get a little longer life out of it, you can also run the risk of explosion.

    If a person were to heat a battery up too much, because of a bad short inside or similar, they migh find new meaning to the Big Bang theory... Not really any difference than over charging a capicator and blowing it up.. a battery is basically the same thing...
  6. Ed in Tx

    Ed in Tx Super Member

    Yep I agree with the hazard. While I have opened up shorted NiCads I've done it with very brief connects, no time for anything to heat up and expand. About 1 second at a time, then check to see if the short's gone, if it is, then put the battery on a regular charger and let it charge normally. Li-Ions though are a different thing altogether. Some Li-Ions have internal charge monitoring circuitry built into the battery pack.
  7. ozmoid

    ozmoid Lunatic Member

  8. mhardy6647

    mhardy6647 AK Subscriber Subscriber

    I thought that lithium-ion batteries were (relatively) immune from memory effects and allowed much higher numbers of charge/drain cycles than 'the competition'...(?)
  9. SaSi

    SaSi AK Subscriber Subscriber

    Well, I started the test early in the evening as soon as returned home. I had left the MD player plugged in so it should be fully charged.

    I started playback of a disk in repeat mode with the volume set to 5/20 and DSL (bass boost) set to 3/3. This is pretty loud with the earplug headphones I have.

    I started at 19:15 local time (GMT+2) and it is now 1:15 local time. It's been 6 hours and it still plays happily. The battery indicator is at 1/3 for sometime now - I missed the transition. I assume that a 6 hour flat operation is harder for the battery than interrupted use of 30 min ~ 1 hour - is that correct?

    Anyway, the battery may still be alive and kicking, but I really need to turn in, so the test will stop now and continue tomorrow evening.

    @Osmoid: Thanks a lot for the link. It was very enlightning.
    @Mhardy: Li-ion batteries don't suffer from memory effect. What they don't like is a total drain, almost the same as lead-zinc batteries.
  10. Cantabury Guy

    Cantabury Guy Super Member

    Would the battery in question be one of those BP 2X?

    DENNYDOG Addicted Member

    You could probably find a single 3.6v lithium ion battery that you could modify to fit. I believe that 3.6v is the standard for a single cell Li-Ion.
  12. Strawman

    Strawman Moderator

    that's what I wou;d be thinking Denny, battery life cycles are going to be a wonderful future for the next generation. Just pay attention to the MaH rating SASI.
  13. SaSi

    SaSi AK Subscriber Subscriber

    Modifying readily available cells might be what I will be forced to do in the future (perhaps near). Problem is the battery for the unit (LIB-902) is a long (3") and thin rectangular shaped brick. Threre certainly isn't much space for 3xAAA cells. It might be feasible to use 3x3.6V cells wired in parallel.

    The LIB902 battery gives a 700mAh rating
  14. KingBubba

    KingBubba "Too Much Stuff" Subscriber

    Some battery places will do rebuilds by replacing the cells inside the cases.
  15. cbrworm

    cbrworm Well-Known Member

    I do a lot of work with Lithium ion battery packs. We have had more than a few of them burst into flames during charging. It is not something you want to witness inside a building or vehicle. This is usually due to corrosion or some other imperfection inside the roll.

    In the real world they have a useable life of about 1 to 2 years regardless of number of cycles. They will self discharge to a point that they need to be jump started, but usually that is due to the monitoring circuitry that is typically in the pack not having enough energy to run and thus not allowing any charge current into the cells. In our battery packs we actually have current and voltage limiting devices as well as real time individual cell temperature and voltage monitoring to prevent charging outside of acceptable parameters. The circuitry also has the ability to completely and permanently disconnect the cells from one another in a catastrophic event to keep damage to a minimum. This is all backup to the circuitry which is in the charger that also monitors every piece of data through the SMBUS.

    Normally to jump start a battery we will supply it with it's operating voltage, or slightly higher at a medium current rate (depending on it's capacity) and carefully monitor the batteries temperature. Usually they only need 10-20 seconds to get enough of a charge to allow the devices built in charging circuitry take over and work.

    What you are describing is pretty dangerous. I would not recommend jumping it again unless you are outside and wearing glasses.
  16. mhardy6647

    mhardy6647 AK Subscriber Subscriber

    hmmmmpf. the inexorable progress of technology, I guess :p
  17. ozmoid

    ozmoid Lunatic Member

    They are immune from the same type of "memory charge" effect that Nicads are susceptible to.
  18. Vinylrockrob

    Vinylrockrob Active Member

    Ahhaa, Well my 3 years are up for the original one thats why I got a new one.:yes: Was wondering why the charge depleted quickly. Thanks.
  19. MusicMtnMonk

    MusicMtnMonk Local Yokel

    You've checked here to make sure nothing will work for you

    If it was me I'd be SUPER careful messing with those Li Ion batteries, always wearing safety glasses. From the video's on the internet, those Li Ion batteries are very flammable and explosive under the wrong charge...
  20. SaSi

    SaSi AK Subscriber Subscriber

    I continued the "test" today. The player went on for another 3 and a half hours before it shut down. 9,5 hours total with specs for 10 hours. Doesn't look bad.

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