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Safety of rechargeable batteries?

  1. Jun 18, 2009 #1
    We bought some rechargeable batteries a few years ago. However, we managed to lose the charger that went with it. :uhh: Now we bought some new rechargeable batteries with a new charger. This one is of a different brand.

    We still have the old batteries. My dad wants to use the new charger with the old batteries, but I'm worried that this might have some dangers. All the warning labels on the box and the batteries themselves have really made me worried, and I want to get rid of the old batteries. (I don't want to end up blowing up my house just to save a few batteries!)

    I'm sure many people here know more about rechargeable batteries than my father or I do. What would you advise?

  2. jcsd
  3. Jun 18, 2009 #2


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    Try it in your neighbours house first. :P

    Maybe you can pull a search online. Give us some info. on these batteries because I haven't got a clue what you might have.
  4. Jun 18, 2009 #3
    What technology batteries? Is the recharger a trickle charger?
  5. Jun 18, 2009 #4
    Last edited by a moderator: May 4, 2017
  6. Jun 18, 2009 #5
    Ideally this thread should be placed in the Electrical Engineering folder that is currently
    monitored by a plethora of bored electrical engineers.

    Usually your rechargable batteries are NiCads. 'NiCad' is the name of one technology. There are also NiMH and Lithium Poly. Most stuff around the house is NiCad. Always use a charger made for the technology labeled on the battery. The only batteries that could be a fire hazard out of the three are Lithium Poly (LiPo, Lithium Polymer).

    If you are really worried, find an extension cord and run it out the window or something.
    Last edited by a moderator: May 4, 2017
  7. Jun 18, 2009 #6


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    The specs look comparable, and there's a comment on the second one saying you can use your other chargers for them. The battery types look the same.

    Edit to respond to Phrak: Both of these battery types are listed as NiMH.
  8. Jun 18, 2009 #7
    Thanks for all your replies. It seems reasonably safe, so tomorrow, I will pay a visit to my neighbor. :D just kidding

    I like how you put it that way. :smile: I had been looking for a more appropriate place to post this, but I don't even know what electrical engineering is...
  9. Jun 18, 2009 #8


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    It could also go in one of the technology forums. Don't worry about it though. The mentors here will take care of moving it to a better forum if they think it belongs someplace else.
  10. Jun 19, 2009 #9
    I'm glade to see NiMH taking over. NiCads are actually NiMH with cadmium used in some fashion an electrochemist would know about, but other materials have been found that replace the toxic cadmium.
  11. Jun 19, 2009 #10
    And nickel salts aren't toxic?
  12. Jun 19, 2009 #11
    Oh, an expert.

    Zn, Cu, and Al are also toxic. What are relative toxicities of Ni and Cd. Which is treatable?
    Last edited: Jun 19, 2009
  13. Jun 19, 2009 #12


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    There is nothing unsafe about mixing chargers and batteries from different brands, as long as the charger is designed to charge batteries of that chemistry (NiMH in this case).

    Most modern chargers will auto-detect the battery chemistry and refuse to charge batteries of the wrong chemistry anyway.

    - Warren
  14. Jun 19, 2009 #13
    You won't hurt anything by using the wrong charger or batteries. Just do it in the garage or outdoors.
  15. Jun 19, 2009 #14
    Last edited by a moderator: Apr 24, 2017
  16. Jun 19, 2009 #15


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    First epileptic seizure induced by occupational nickel poisoning.
    Of course, this required high levels of exposure.

    Nickel salts should not be injested.

    About 10-20% of the population are allergic to nickel.

    Toxicological Profile for Nickel

    Toxicological Profile for Cadmium

    Cadmium is more toxic than nickel.

    Transitional (including heavy) metals are removed from the body with 'chelation therapy'.
    Last edited by a moderator: Apr 24, 2017
  17. Jun 19, 2009 #16
    I don't believe there is any treatment for Cd behond immediate treatment with the ingestion of Zn. Cd accumulates in the kidneys.

    Chronic toxicity of Cd ions by ingestion (whatever that means) is 50 to 100 micrograms per day per kilogram of body weight, far in excess of Ni, which is why there is nickel coinage, but cadmium plated screws are no longer found at the hardware store.

    Nickel toxicity is not as well qualified.

    An interesting subject. I wish I could relocate the references I'd found.
    Last edited: Jun 19, 2009
  18. Jun 20, 2009 #17


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    Whichever type of batteries you use, make sure the charger is the type that turns itself off when the batteries are fully charged.

    NiCd and NiMH batteries start to heat up once they are fully charged.
    Just overheating NiMH batteries once can ruin them.

    So spending $20 on batteries and then using a $10 charger that doesn't turn itself off seems like bad economics.

    The new batteries you mention are very good. They come fully charged and hold a high percentage of their charge if unused for a long time.
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