[NSRCA-discussion] Max volts

Mon Mar 1 16:10:23 AKST 2010

Along the lines of taking advantage of better batteries, ESC's could compensate for packs as they flatten out.  Essentially, an ESC could be designed to automatically de-rate the battery when it is above a prescribed level of charge.  I don't really keep up with what the various ESCs have feature-wise, but I haven't heard of this being done yet.  I don't think it would be hard either.  Effectively, it's like a built-in ATV that simply limits the pulse width at full power when the battery is above a certain level, just as it already does in response to throttle inputs.  There's an advantage to this in that the battery pack & wiring arrangement stays simple and that all cells in the pack get used simultaneously.  I still like Jim's original idea, especially because it got some more thinking on the topic going.

Ed

From: AtwoodDon at aol.com 
Sent: Monday, March 01, 2010 8:01 PM
To: nsrca-discussion at lists.nsrca.org 
Subject: Re: [NSRCA-discussion] Max volts

This approach could also function as a backup RX battery.  No rules against having redundant RX power.  The BEC could be programmed to 'divert' power to the flight batteries to maintain the near max voltage when needed.

However, I agree with Jim, I don't see the need for this.  Battery technology has/is progressing fast enough to provide us with enough power for our sequences.  I prefer the simpler approach.

Don

In a message dated 3/1/2010 4:34:31 P.M. Pacific Standard Time, ed_alt at hotmail.com writes:
  That's a good idea.  I imagine it would take a little modification to the 
  rule to specify how a system like this could be applied.  This could be put 
  together external to the speed controller and function automatically through 
  active voltage sensing.  Eventually the ESC mfgs could go a step further an 
  just integrate this right into the controller.  Slick, simple concept Jim!

  Ed

  --------------------------------------------------
  From: "James Oddino" <joddino at socal.rr.com>
  Sent: Monday, March 01, 2010 7:15 PM
  To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
  Subject: Re: [NSRCA-discussion] Max volts

  > I have the functional concept that solves the rules problem.  Picture a 
  > 10S pack positive lead wired to the common of a switch with two poles, a 
  > piece of wire connected from one pole to a pole on a second two pole 
  > switch with its common connected to the ESC.  Between the other two poles 
  > we place our 11th cell.  When the 10S pack is above 37.5 volts the 11th 
  > cell is bypassed and when it is below, like it will be during vertical 
  > maneuvers late in flight, the 11th cell is put in series to boost the 
  > voltage to up to 41.7 volts.  At no time is the voltage over the spec.
  >
  > Having said that, I believe the 10S system provides adequate power with 
  > the right motor at all times of flight even if the voltage drops to 35 
  > volts.
  >
  > Jim
  >
  >
  > On Mar 1, 2010, at 8:59 AM, Bob Kane wrote:
  >
  >> Going higher and regulating down would be against the rules, the max 
  >> volts is still limited to 42.56.
  >>
  >> Bob Kane
  >> getterflash at yahoo.com
  >>
  >>
  >> --- On Mon, 3/1/10, krishlan fitzsimmons <homeremodeling2003 at yahoo.com> 
  >> wrote:
  >>
  >>> From: krishlan fitzsimmons <homeremodeling2003 at yahoo.com>
  >>> Subject: Re: [NSRCA-discussion] Max volts
  >>> To: chad at f3acanada.org, "General pattern discussion" 
  >>> <nsrca-discussion at lists.nsrca.org>
  >>> Date: Monday, March 1, 2010, 9:54 AM
  >>>
  >>> Couldn't we go to a higher voltage and
  >>> regulate it back down? A contstant 42.56v would be nice!
  >>>
  >>> Chris
  >>>
  >>>
  >>>
  >>>
  >>>
  >>>
  >>>
  >>>
  >>>
  >>> From: Chad
  >>> Northeast <chad at f3acanada.org>
  >>> To:
  >>> nsrca-discussion at lists.nsrca.org
  >>> Sent: Sun,
  >>> February 28, 2010 8:48:48 PM
  >>> Subject: Re:
  >>> [NSRCA-discussion] Max volts
  >>>
  >>> You would be at about 50% capacity at 3.85 ish volts/cell
  >>> (resting open circuit), so unless you up the capacity you
  >>> will have a pretty restricted flight time.
  >>>
  >>> Chad
  >>>
  >>> On 10-02-28 9:25 PM, Ron Van Putte wrote:
  >>>> That stirs a wild thought in my brain.  Fully
  >>> charged packs don't stay at 4.2 volts per cell very
  >>> long.  On the other hand, once the initial charge
  >>> voltage is burned off by a constant load, the voltage loss
  >>> curve "flattens out".  What if you put fully
  >>> charged 6S and a 5S packs in series and "burn them
  >>> down" to 3.869 volts per cell (a total of 42.56
  >>> volts for an 11-cell pack) so they were legal for
  >>> use.  Would the voltage of this depleted 11S pack be
  >>> higher than a fully charged 10S pack at the end of a typical
  >>> flight?  If the end-of-flight voltage might be
  >>> significantly higher for the 11S pack vice a 10S pack, it
  >>> would be worth investigating, even considering the extra
  >>> weight of the additional cell.  Come on you electronic
  >>> gurus, show me where I'm wrong.
  >>>>
  >>>> Ron Van Putte
  >>>>
  >>>> On Feb 28, 2010, at 10:00 PM, James Oddino wrote:
  >>>>
  >>>>> What comes after ...?  Does it specify a load
  >>> or any other conditions?  Is it measured during the
  >>> noise test and have a minimum value?
  >>>>>
  >>>>> Just stirring the pot, Jim O
  >>>>>
  >>>>>
  >>>>> On Feb 28, 2010, at 5:21 PM, John Fuqua wrote:
  >>>>>
  >>>>>> No its not (assuming we are talking RC
  >>> Aerobatics).  Try page RCA-2 para 4.1
  >>>>>> which
  >>> states "Electrically-powered model aircraft are
  >>> limited to a maximum
  >>>>>> of 42.56 volts.."
  >>>>>>
  >>>>>> -----Original Message-----
  >>>>>> From: nsrca-discussion-bounces at lists.nsrca.org
  >>>>>> [mailto:nsrca-discussion-bounces at lists.nsrca.org]
  >>> On Behalf Of Ron Van Putte
  >>>>>> Sent: Sunday, February 28, 2010 7:07 PM
  >>>>>> To: General pattern discussion
  >>>>>> Subject: Re: [NSRCA-discussion] Max volts
  >>>>>>
  >>>>>> It's in the general rules, not in the R/C
  >>> section.
  >>>>>>
  >>>>>>
  >>>>>> On Feb 28, 2010, at 6:50 PM, Jim Quinn wrote:
  >>>>>>
  >>>>>>> Where can I find the rule
  >>> for max volts?
  >>>>>>>
  >>>>>>>
  >>> _______________________________________________
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  >>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
  >>>>>>
  >>>>>>
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