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Rechargeable 9v Lithium-Polymer batteries — Parallax Forums

Rechargeable 9v Lithium-Polymer batteries

PJMontyPJMonty Posts: 983
edited 2010-10-29 06:31 in General Discussion
Someone has finally made a rechargeable 9v battery that is as good or better than alkalines. I have a number of 9v driven devices (my voltmeter, my guitar fuzzbox, etc) and I hate putting in throw away batteries. Apparently, these Li-Poly batteries have a very low self discharge rate, so they're good for devices that sit around a lot, and they have as much or more capacity as alkalines. The batteries aren't cheap at $15, but they will get used many, many times. Also, the charger can charge both Li-Poly as well as NIMH and NiCD.

toolmonger.com/2007/10/13/a-more-powerful-long-lasting-rechargeable-9v-lithium-polymer/

Thanks,
PeterM

Comments

  • Tracy AllenTracy Allen Posts: 6,666
    edited 2007-10-14 00:15
    I've been following those developments too, because there are so many apps that could benefit from a good high capacity 9V rechargeable. Their advertising is a little off about the capacity of good alkalines, which Energizer specs at 600 to 650 milliamp hours at light loads, which is more, not less than the 500mah capacity claimed for these Li-polys. The initial voltage of the Li-polys is 8.4 volts, but I'd really really like to see a family of discharge curves to see if it is flat or if it falls off gradually. They state an end of discharg voltage of 6.8 volts. The specification sheet for the iPower battery is posted at www.ipowerus.com/specs/9v500mah_spec_060411.htm

    Batteryspace has a 9v Li-polymer with similar specs at $8 each. If those can be recharged conservatively 100 times, then that is 8 cents per use and only one battery to recycle.

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    Tracy Allen
    www.emesystems.com
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2010-10-28 11:02
    Height: Width: Thickness:
    48.0 mm x 25.0 mm x 15.0 mm. reg 9 volt battery
    49.2 mm x 26.8 mm x 17.8 mm. Li-polys 9 volt battery

    This battery may not fit in very many 9 volt battery box compartments
  • CampeckCampeck Posts: 111
    edited 2010-10-28 13:09
    will these be worthless if discharged too much like my heli batteries?
  • Dave HeinDave Hein Posts: 6,347
    edited 2010-10-28 13:38
    The battery has a built-in protection circuit that should prevent it from being discharged too much. This battery may not work in all 9-volt applications because it's operating range is from 6.5 to 8.4 volts. The voltage on Li-Po batteries decreases slowly as they are discharged. The rate of voltage drop increases as they become more drained.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2010-10-28 20:16
    The only thing that really bothers me is that the voltage for the chemistry isn't quite right, and in order to to get it to the operating voltage you need to dope the Lithium with impurities. This translates to cells that may not work optimally. For the size though 500mAH is about the right Power density (4.5Wh) for Lithium so I don't know... I would be a little skeptical.
  • schillschill Posts: 741
    edited 2010-10-29 05:56
    When I hear LiPo, I immediately start looking for multiples of 3.7V.
  • Dave HeinDave Hein Posts: 6,347
    edited 2010-10-29 06:12
    It is a multiple of 3.7 volts. It's basically a 2-cell 7.4-volt battery with an operating range of 8.4 to 6.5 volts. This is typical of LiPo cells, except that the lower end would normally be 6 volts for 2 cells.
  • schillschill Posts: 741
    edited 2010-10-29 06:31
    Sorry. My statement wasn't at all clear. I just meant that I'm not used to seeing a range quoted - usually just a single value that's a multiple of 3.7.
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