Jetbeam        
Results 1 to 4 of 4

Thread: NiCad/NiMH charger question

  1. #1
    Flashaholic* Timothybil's Avatar
    Join Date
    Nov 2007
    Location
    The great state of Iowa
    Posts
    2,743

    Default NiCad/NiMH charger question

    I know an NiMH charger can also charge NiCad cells, but can a Ni-Cad charger also charge NiMH cells. Specifically, I am thinking of the Ni-Cad battery pack of a Dremel tool. It is rated 7.2v, and there are four cells wired to provide 3.6v and 7.2v for two speed operation. I would rather not replace the existing cells with more Ni-Cad, but with either NiMH or a LiPo battery pack. If worse comes to worst, I will just wire in an external jack and make up an external Li-Ion pack with a medium length cord.
    You don't NEED a parachute to skydive. You DO need a parachute to skydive twice.

  2. #2

    Default Re: NiCad/NiMH charger question

    Forgive me for what may seem like a dickhead response but I feel you may want to go do a bit more reading before jumping into battery packs given the info you have provided. IIRC NiCad batteries are 1.2v(nominal) so 4 would not give you 7.2v for that you would need 6. If you've pulled it to bits and see 4 batteries in 2 pairs then you are most likely looking at a 2s2p configuration which gives you 2.4v and then a doubled capacity. NO manufacturer in their right mind you make a battery pack where 2 batteries are used for low speed then 2 others as 'switched on' in series to increase voltage, this would cause all kinds of charge and discharge issues and probably result in very imbalanced over charged/discharged cells. I've had a couple of older battery operated dremels and they were 2.4v and worked aswell as an ant pissing in a water wheel. The cost of making yourself a new pack for this would probably be as much as buying a new dremel. If it has sentimental value then just restore it to OE condition box it up and store it. Otherwise scrap it, fucking around with batteries (especially Lipo's) is ill advised. Sorry to piss in your parade but I'd rather you go away a little disheartened than go away and blow some fingers off.

  3. #3
    Silver Moderator
    SilverFox's Avatar
    Join Date
    Jan 2003
    Location
    Bellingham WA
    Posts
    12,215

    Default Re: NiCad/NiMH charger question

    Hello Timothybil,

    Yes you can charge a NiMh battery on a NiCd charger BUT...

    The charge termination on NiCd is a little higher than required on NiMh so you will tend to overcharge and overheat the NiMh battery.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

  4. #4
    Flashaholic* Timothybil's Avatar
    Join Date
    Nov 2007
    Location
    The great state of Iowa
    Posts
    2,743

    Default Re: NiCad/NiMH charger question

    Quote Originally Posted by SilverFox View Post
    Hello Timothybil,

    Yes you can charge a NiMh battery on a NiCd charger BUT...

    The charge termination on NiCd is a little higher than required on NiMh so you will tend to overcharge and overheat the NiMh battery.

    Tom
    Thanks. I kind of figured there would be something like that. As was pointed out to me, it does not make economical sense to rebuild a Dremel battery pack, especially when one can get a new one for about $20.
    You don't NEED a parachute to skydive. You DO need a parachute to skydive twice.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •