[NSRCA-discussion] Fwd: New fast charge battery

Thu Mar 19 21:09:17 AKDT 2009

Going back to my "How many of you guys ever raced R/C cars" question - the reason I asked is because if you did you'd already be thinking like Dave. Well, not exactly. I don't believe anyone can think like Dave! LOL

Back when I raced, we used NiCADs. Why? Because that's all we had. We had basically 2 kinds: high output / fast charge (SCR) and high capacity / slow charge (SCE) types. At the risk of oversimplifying - the difference had to do with internal resistance. For stock class we ran the high output type, for modifieds we used the high capacity type. To get Max performance from the high output batteries in stock class we charged them at 1 - 4C, then we re-peaked them before the race at 10 - 30C! Some guys used to charge until the cell vents opened. The result: a super hole-shot, lotsa power, 4 minutes worth of fun. Then we threw the battery pack out. They could only handle this kind of abuse once. You didn't do this every weekend, just for the really big events. OK, if you were spoonsored you did this all the time. :)
The high capacity batteries had to be treated differently. Normally you charged at 1-4C. In a 2WD modified car you could expect to get at least a few cycles before you used the pack for practice. If you were "cheap" you'd take a pack that had been used 4 or 5 times, put it on a trickle charger overnight to "re-balance" the cells (sound familiar?) and used it until it dumped on the last lap and cost you a race. If you were sponsored you always had brand new "computer matched" batteries so you didn't have to do this.

Bottom line: You can't have everything. You're going to trade off something. You need to understand exactly what you're getting with a new technology and if it's worth giving up something that the existing technology might do better. I doubt very much that you'll see a 30C discharge rate + 3C charge rate capable pack that weighs half as much as what we have now AND delivers more usable cycles as well. But I guess we can dream. VBG

John Pavlick
http://www.idseng.com
  ----- Original Message ----- 
  From: Dave 
  To: 'General pattern discussion' 
  Sent: Thursday, March 19, 2009 9:54 PM
  Subject: Re: [NSRCA-discussion] Fwd: New fast charge battery

  The faster you charge, the fewer the cycles you get!!  Figure cycle life is reduced by about 50% at 3C charge rates.

  Regards,

  Dave

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  From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Stuart Chale
  Sent: Thursday, March 19, 2009 6:48 PM
  To: General pattern discussion
  Subject: Re: [NSRCA-discussion] Fwd: New fast charge battery

  The key in my mind as we already have enough power in a makable weight for a new set of batteries, is the number of cycles you can get.  It the new technology gets us 200 cycles before degradation then I'll take 2 :)  Don't need three any more because they charge faster.
  Stuart

  Ed Alt wrote: 

  This is very straightforward.  The ideal battery is one that has 0 ohms internal resistance and infinite current delivery capability.  This new technology gets you somewhat closer to that ideal.  All it means is that it minimizes power losses due to much lower internal resistance, and reduces limitations that are placed on the performance of the thing you are powering with it.  Even the ideal battery can only deliver as much current into the load as that device will draw based on its own resistance (actually impedance, but we'll keep it simple) Doesn't matter whether it is a motor, a light bulb or whatever.  It's all good...

  Ed

    ----- Original Message ----- 

    From: Keith Hoard 

    To: General pattern discussion 

    Sent: Thursday, March 19, 2009 5:15 PM

    Subject: Re: [NSRCA-discussion] Fwd: New fast charge battery

    How good would these batteries work in my glow starter?. . .

    2009/3/19 Ed Alt <ed_alt at hotmail.com>

    No way! That is simply evidence that your paint needs to be upgraded!

      ----- Original Message ----- 

      From: Rex 

      To: NSRCA-discussion 

      Sent: Thursday, March 19, 2009 4:33 PM

      Subject: Re: [NSRCA-discussion] Fwd: New fast charge battery

      Now I'm just guessing here....  I'm thinking that if you throttle up and the paint
      strips off the fuse, that's probably a bit too much!

      Rex

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      From: joddino at socal.rr.com
      To: nsrca-discussion at lists.nsrca.org
      Date: Thu, 19 Mar 2009 14:10:06 -0700
      Subject: Re: [NSRCA-discussion] Fwd: New fast charge battery

      I used to say that an engine is a machine that doesn't make enough power.  Now I say a motor is also a machine that doesn't make enough power.   

      Jim

      On Mar 19, 2009, at 8:29 AM, J N Hiller wrote:

        Hay Rex how much power do you need? You can do a vertical ROG now.

        Jim

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    -- 

    Keith Hoard
    Collierville, TN
    khoard at gmail.com

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