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About Rechargeable batteries

Discussion in 'Pickups & Electronics [BG]' started by semborg, Aug 22, 2005.

  1. Okey so the night before I have a gig I usually want fresh batteries. My father tells me that it is OK to charge the batteries even if they maybe are just half power.

    Is this really okay to do?
  2. Ni-Cad, generally NO, full discharge, full recharge. If you fill up when you're only halfway discharged, it tend to make the battery remember "that's where I got charged last time, that must be the "empty" position. Ni-Cads tend to have "memory".

    NI-MH batteries are supposed to be forgetful, you can charge them anytime, no "memory" effect.

    Li-Ion also, no memory effect. Better even than NI-MH in that regard.

  3. I have NI-MH :)
  4. Pickebass

    Pickebass Supporting Member

    Jul 12, 2004
    San Antonio, TX
    What are you using the pickups for? If you are using it for a wireless, don't! Rechargeable batteries do not give consistent power to your electronics. If you are using a wireless this can cause other problems with feedback etc. With electronics that are expecting a consistent voltage, this can dramatically effect your sound.

    Not a product pitch, but some batteries are better because they deliver a consistent voltage until they are empty. For instance, Duracells maintain a full charge until they drop and then there done quickly afterward
  5. Depends, the voltage is usually lower, 8.4v vs 9v or 1.2v vs 1.5 volt for AA. Sometimes that's an issue, sometimes it not. I use NI-MH AA batteries in my Xwire, and they last all night with no probs, almost 2 nights if I forget to recharge overnight. They tend to be more stable than alkaline for the majority of their life, then drop faster at the end. This throws the battery meter off, it shows 10 or 11 hours remaining for most of the time, then when it starts to go down, it goes fast. 9 to 8 to 7 to 6 in a couple hours. Maybe that's just these particular batteries.

    If your wireless uses a 9 volt, they may not have as much endurance as the alkaline, I'm not sure about those. Not sure if they'll last a whole night, but you can always charge 2 and swap after a couple sets.

    The main prob is that they tend to be MORE stable, instead of a slow gradual drop that give you plenty of warning before they go dead, they drop too fast and you don't necessarily get enough time to recognize the problem and replace the batts before it drops out.

    That's been my experience anyway, but I've used AA cells, not the 9v ones. They may have less endurance than alkalines, not last a whole night. But find out how long they last, and just swap after 2nd set if they last 3 sets.

  6. as long as you don't do it every night, you should be fine. Provided you cycle the batterys every few times (ie; full discharge, full recharge) they'll be fine.

    Now, rechargeable batterys actually have a much flatter discharge curve than regular batterys. Especially Ni-Mh and Li-Ion. This means that they drop voltage initially from fully charged, but tend to stay pretty constant until they die suddenly at the last minute. Where as alkaline batterys cannot sustain a constant voltage for very long.

    The problem Pickebass is encountering seems to be the opposite of what I would expect. But, perhaps it has something more to do with the fact that rechargeable batterys have lower cell voltages than alkalines.

    A Ni-Mh "9V" usually consists of 7x1.2V cells = 8.4V.
    An alkaline is 6x1.5V cells = 9V.

    (there are 8 cell Ni-Mh available too)

    So, a fully charged Ni-Mh might measure 9V, but the cells won't hold that for long. Mind you, nor will alkaline cells! However, the different types of battery will sustain a different steady voltage during normal use - which may or may not cause equipment to malfunction.
  7. As pointed out above, the Dark Side of rechargeable batteries is most have lesser voltage than nominal.

    Most preamps prefer twice the nominal voltage (18v instead of 9v) because this offers more headroom. Providing less than nominal (8.4v) to your preamps may starve them and impact the sound. YMMV.

    NiCAD do indeed have the memory effect. This can be somewhat cured by letting them run all the way down before recharging.
  8. luknfur


    Jan 14, 2004

    interesting thread and not something I've looked into much outside of what was necessary for application - which for me, didn't amount to much.

    Unlike most player's comments on battery life, mine didn't last long so I went to rechargeables in short order. Whole different world where I find 9v really doesn't apply to the either voltage or the physical size. Different voltages, different sizes, different milliamps. You REALLY have to watch what you buy in rechargeables because their output varies from practically alkaline duracell to not even enough to run an onboard preamp when new and fully charged.

    My basses would run fine down to about 7.3V or so (never found any real use for 18v) and the rechargeables at full charge were somewhere around 9. Rechargeables initial full charge drops off quickly. In fact from what I've read they'll fall off as much whether they're used or not (It is recommended to refrigerate charged but unused rechargeables. From what I understand, it's just wivestales for non-rechargeables).

    You can get some rechargeables that are considerably smaller that typical 9v's which can be a real plus in a tight spot or fitting in an 18v instead of just a 9. They tend to be the lower powered ones though - at least the ones I have.