[NSRCA-discussion] NiMH follow up

[Ed Miller]

The 2/3A size NimH cell from Batteries of America (  ehyost at chorus.net ) are made by Panasonic. I have 2 of their 5 cell packs rated at 1100mah and my most recent purchase was a 5 cell pack rated at 1250mah.  With a 8" long heavy duty wire Futaba pigtail the 5 cell pack weighs 3.85 oz.  I do not believe Sanyo makes a 2/3A size NimH cell.  The 2/3A cell is shorter, slightly larger in diameter and lighter than a traditional AA cell.
Ed M.
  ----- Original Message ----- 
  From: Michael Cohen 
  To: NSRCA Mailing List 
  Sent: Monday, February 27, 2006 10:33 PM
  Subject: Re: [NSRCA-discussion] NiMH follow up


  So, what are the "good" ones?  Sanyo, Panansonic, another brand?  
    ----- Original Message ----- 
    From: Dean Pappas 
    To: NSRCA Mailing List 
    Sent: Monday, February 27, 2006 8:16 AM
    Subject: Re: [NSRCA-discussion] NiMH follow up


    Aha!
    Hi Ed,
    The "good" low resistance NiMh cells don't need a couple of conditioning cycles to come to full capacity. I confirmed this with both Larry at SR Batteries, and with Steve at NoBS Batteries.
    Both sets of  900H cells that I bought several months ago, checked within 1% of their best capacity after the first cycle. I was told that is normal, and to still stick to a max C/2 fast charge.

    Dean

    Dean Pappas 
    Sr. Design Engineer 
    Kodeos Communications 
    111 Corporate Blvd. 
    South Plainfield, N.J. 07080 
    (908) 222-7817 phone 
    (908) 222-2392 fax 
    d.pappas at kodeos.com 

      -----Original Message-----
      From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Ed Alt
      Sent: Monday, February 27, 2006 6:40 AM
      To: NSRCA Mailing List
      Subject: Re: [NSRCA-discussion] NiMH follow up


      Ed:
      Yep, 1/10C would be 220 mA for your 2200 mAh pack.  To condition a NiMh pack when brand new, you do several conditioning charges at 1/10C.  You want to go a full 24 hours at 1/10C, do a discharge to complete a cycle and repeat for a total of 3 or 4 full cycles.  This will generally get you to full capacity and also gets the cells ready to accept higher rate charging and with the right charger, they will then start to give a reliable indication of when they have peaked.  After these first conditioning charges, you do not want to exceed about 16 hrs at 1/10C, though at 1/10C it's a low enough rate that you're not going to damage it if you do go over.  Anything higher than 1/10C can shorten the life of the cells if repeated overcharging is done.  The higher the rate and the more time it is overcharged, the faster the degradation can occur.

      Ed


        ----- Original Message ----- 
        From: Ed Deaver 
        To: NSRCA Mailing List 
        Sent: Monday, February 27, 2006 12:57 AM
        Subject: Re: [NSRCA-discussion] NiMH follow up


        OK, for us non-electical whiz bang guys, please explain the C charge.  I have heard it before and tried what was suggested on RCU without success.

        My new NmHD pack is a 2200mah, 4 cell pack.  To condiditon it properly for first flights what should I do?  

        Does 1/10 C mean charge at 220 mah for 16 hrs??

        THanx for the explanation.

        ed

        Michael Cohen <precisionaero at comcast.net> wrote:
          Thanks to those who helped me with the advice. The 1/10 C change was the 
          answer. Both packs are happily at 1610-1690 capacity for their 1650 rating. 
          I also visited an old friend's website, Electrodynamics in Michigan. They 
          had an interesting write up on their website about NiCD (with a little NiMH 
          sprinkled in! ). I used to buy all my switches, extensions, and battery packs 
          from them when I lived in the Great White North. Their advice was 1/10 C 
          also, but they had lots of other good info there as well. I recommend you 
          take a look, unless your one of those Lithium people.

          Mike Cohen 


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