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Thread: NiMH in NiCad charger?

  1. #1
    Flashaholic*
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    Default NiMH in NiCad charger?

    What happens if you recharge NiMH batteries in a NiCad charger? What exactly is the difference in the way they need to be recharged? The first set of NiMH batteries I got, from Radio Shack at least 1 1/2 years ago, have been charged only in a NiCad charger. They seem to work fine, giving around 3 times the life of a standard AA NiCad. I purchased an Eveready charger, that has a switch for NiCad/NiMH. Now that I'm getting more and more of the NiMH AA batteries, (Rayovac 1600 mAH AA's from Walmart; $11/4PK +tax)I'll need to get 1 or 2 more chargers. (Probably for AAA/AA only) But I wonder what I may have done to the set of NiMH I've been rechargeing in the NiCad charger. [img]images/icons/blush.gif[/img] [img]images/icons/frown.gif[/img]

  2. #2
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    Default Re: NiMH in NiCad charger?

    I don't see anything wrong with what you've been doing, but if I were you I would get a pulse type unit.
    That way, you won't have to make a Career out of charging batteries [img]images/icons/tongue.gif[/img] and it's supposed to be a lot easier on 'em.
    *editorial-I used to hate rechargeables bcos you had to "babysit" them, and wait hours and hours and More hours.... [img]images/icons/frown.gif[/img]
    -I just now put in an exhausted NimH AA-1600mAh, but I will have that battery Back in full service in 90min! [img]images/icons/smile.gif[/img]

  3. #3

    Default Re: NiMH in NiCad charger?

    I found that on one type of charger, the NiMH/NiCd switch was just a 'feel good' switch. The idea is that NiCds will accept a higher charging rate compared to NiMHs. The thing was that the maximum charging rate was a fair amount LOWER than the maximum allowable charge rate for the NiMH batteries.

    Thus, the switch did nothing at all. I have been charging NiMHs on NiCd chargers for years without problems. I do, however, tend to use a lower charge rate (140 mA) unless I am in a hurry, as I feel that the heat generated by the rapid charger (240 mA) is detrimental to the cells.

    Walt

  4. #4
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    Default Re: NiMH in NiCad charger?

    <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Walt Welch:
    I found that on one type of charger, the NiMH/NiCd switch was just a 'feel good' switch. The idea is that NiCds will accept a higher charging rate compared to NiMHs. The thing was that the maximum charging rate was a fair amount LOWER than the maximum allowable charge rate for the NiMH batteries.

    Thus, the switch did nothing at all. I have been charging NiMHs on NiCd chargers for years without problems. I do, however, tend to use a lower charge rate (140 mA) unless I am in a hurry, as I feel that the heat generated by the rapid charger (240 mA) is detrimental to the cells.

    Walt
    <HR></BLOCKQUOTE>

    Not necessarily an argument with that, but on the newer rapid-pulse units I've been using, the cells are always only mildly warm when they're through charging.
    (The included manuals mentioned thermal detection circuits, amoung several other protective features...
    -That's probably why these type chargers are noticeably more costly.
    BTW-I've been able to save about 20 batteries, using this device,
    -that I would have had to throw away otherwise.

  5. #5
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    Default Re: NiMH in NiCad charger?

    I was wondering if it was a good idea to run a fan over the charger while charging batteris? It does keep the cells significantly cooler. Or at least the outside temp, not sure about the internal temperature.

  6. #6
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    Default Re: NiMH in NiCad charger?

    <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by cave dave:
    I was wondering if it was a good idea to run a fan over the charger while charging batteris? It does keep the cells significantly cooler. Or at least the outside temp, not sure about the internal temperature.<HR></BLOCKQUOTE>

    Sure wouldn't hurt matters.-As you know, too much heat sure doesn't help rechargeables...
    -If those batts. are hot to the touch-(I occasionally check 'em on my inner forearm), a small fan sounds like a good idea.

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