[NSRCA-discussion] Scary night of flying

Sun Aug 22 10:07:10 AKDT 2010

  This is why I'm a big fan of the West Mountain CBA.  I've attached a
screen grab of the discharge curve graph I did this spring of the battery in
my Evolution.  My Evolution sat in my garage from September 2008 until the
spring of 2010 with no maintenance whatsoever done to the battery.  I
charged the battery and then ran a discharge curve on the CBA, overlaying
the results on the graph I made when the battery was new.  The red and black
lines are the curves from when the battery was new, the green curve was
after the battery had sat for an entire year.

   The point I'm trying to make is that if you make a graph when a battery
is new, then you can continue to overlay discharge curves as the battery
ages or undergoes some significant event where you think it may have been
damaged.  By comparing the curves on the same graph you can tell immediately
if the battery is losing capacity or the ability to hold voltage under
load.

   Curiously, the A123 batteries I have don't seem to show any degradation
no matter how many amps I draw from them or after sitting for a year.  In
fact, if you look at the attached graph, the green line shows an improvement
over when the battery was new. . . go figure?

On Sun, Aug 22, 2010 at 12:29 PM, Paul LaChance <plachance at cox.net> wrote:

>  Jon,
>
> Good to hear from you again.  We met at the 2008 NATS.
>
> I plan to switch to the Li Ion packs, but cannot afford to do so at this
> time.  ANY flying I do right now is still on a VERY tight budget.  Life and
> the economy caught up with me right after the NATS.  I am just now getting
> to the point I can start to fly again.
>
> I thought that was the case about fast charging, so flying tonight is
> probably not going to happen.  Although my pack that died last night has now
> cycled to 1600 mah(rated at 1400)  I am trying to go to a contest in 4 weeks
> and trust me...I need all the practice I can get.  Have not flown the plane
> in 2 years since the 2008 NATS.
>
> BTW, I have always done the charge again just to be sure they have fully
> charged.  Taught to me MANY years ago by the man who taught me to fly.
>
> Paul
>
> ----- Original Message -----
> *From:* Jon Lowe <jonlowe at aol.com>
> *To:* nsrca-discussion at lists.nsrca.org
> *Sent:* Sunday, August 22, 2010 12:56 PM
> *Subject:* Re: [NSRCA-discussion] Scary night of flying
>
> Ron,
> I the question was " if NiCad can be quick charged on a first charging or
> do they have to be slow charged like NiMh?". The key word is FIRST. Answer
> is no, they shouldn't be.  Two or three cycles at c/10 are recommended to
> form the cells.  Radical RC has some good info on their website about
> forming charging, and will not warranty cells that are ruined by fast
> charging on the first cycle, whether they be nicads or NiMh.   Some cells
> should never be fast charged, ie ultra high capacity NiMh's.
>
> http://www.radicalrc.com/category/Tx-Packs-NiMH-&-NiCd-20
>
> Nicads and NiMh's can also "false peak" early in the charge cycle when they
> are pretty well drained, making you think they are fully charged, when they
> don't have much charge at all.  If I am peak charging well formed packs, I
> always turn off the charger and turn it oon again when it indicates they
> have peaked to make sure.
>
>  <http://www.radicalrc.com/category/Tx-Packs-NiMH-&-NiCd-20>This whole
> business is why I use Li Ion (not lipo) cells with a regulator for my
> receiver and servos.  Lighter, no memory, very high capacity, durable.
>  Fromeco or Central sell good 2600 mah packs.
>
> Jon Lowe
>
>
> -----Original Message-----
> From: Ron Van Putte <vanputte at cox.net>
> To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
> Sent: Sun, Aug 22, 2010 11:41 am
> Subject: Re: [NSRCA-discussion] Scary night of flying
>
> Nicads can be fast charged. The best charger for nicads that I've used is
> the FMA Super Nova. It has an algorithm which looks at the rate of change of
> voltage in the "automatic" mode. If the rate of change of battery voltage is
> positive, the charger ramps up the charge rate; if the rate of change of
> voltage is negative, it reduces the charge current. It was kind of scary at
> first to watch it do its thing, because the charge current can get pretty
> high. However, that's the sign of a healthy battery. When the charge rate
> doesn't go up much, or not at all, it's time to put the battery in the
> trash. Too bad Fred Marks' sons, who took over the business from Fred, are
> such bozos, or I'd still be doing business with them and selling the Super
> Nova charger.
>
> Ron
>
> On Aug 22, 2010, at 10:37 AM, Paul LaChance wrote:
>
> > Hi all,
> >
> > Thanks for all the advice. I have to admit I did not cycle the >
> batteries before flying this time. They were cycled when purchased > and
> were new for the 2008 NATS. I already bought a new battery but > wanted to
> know if NiCad can be quick charged on a first charging or > do they have to
> be slow charged like NiMh? Thanks in advance.
> >
> > Paul
> >
> >
> > ----- Original Message ----- From: "Lightfoot" <lightfoot at sc.rr.com>
> > To: "'General pattern discussion'" <nsrca-discussion at lists.nsrca.org>
> > Sent: Sunday, August 22, 2010 11:13 AM
> > Subject: Re: [NSRCA-discussion] Scary night of flying
> >
> >
> >> Might well have been a case of NiCad "memory". I wouldn't have >> thrown
> them
> >> away unless after cycling them twice they showed to be weak. Periodic
> >> cycling is a must!
> >>
> >> Jay Marshall
> >> -----Original Message-----
> >> From: nsrca-discussion-bounces at lists.nsrca.org
> >> [mailto:nsrca-discussion-bounces at lists.nsrca.org<nsrca-discussion-bounces at lists.nsrca.org?>]
> On Behalf Of >> Paul LaChance
> >> Sent: Saturday, August 21, 2010 10:57 PM
> >> To: General pattern discussion
> >> Subject: [NSRCA-discussion] Scary night of flying
> >>
> >> Hi all,
> >>
> >> I finally flew my Prestige tonight after not flying it since the >> NATS
> 2008.
> >> I have not flown it or ANY planes for 2 full years. I charged >>
> everything up
> >>
> >> and all seemed well. Flew my first flight and landed without >>
> incident. I
> >> checked the plane over and checked all my batteries and all looked >>
> well.
> >>
> >> Flew flight 2, all was going well. Flew the Advanced pattern >> twice
> and
> >> landed. Checked my batteries again and they still read over 6 volts.
> >> Engine was running great and all was well.
> >>
> >> Flew flight 3 and that is where things got scary. I flew the >> sequence
> once
> >> and everything was going well. When I started my second sequence >> the
> plane
> >> got sluggish and was not feeling right. I landed ASAP and as soon >> as
> the
> >> wheels tounched down, I went to add rudder to stear towards the >> pits
> and had
> >>
> >> no rudder, no elevator, and only one aileron was working but it >>
> barely moved
> >>
> >> and was very sluggish. I shut the plane off and checked the >> batteries
> and
> >> they were barely reading 4.5 volts. This was a 5 cell nicad >> pack. I
> guess
> >> I had a cell short and kill the pack. I was just amazed and am >> very
> lucky
> >> to have been able to get the plane back on the ground before the >>
> battery
> >> completely failed.
> >>
> >> Has anyone had this happen before? What would cause this? I am >> going
> to
> >> get a new pack in the morning and try to fly again tomorrow evening.
> >>
> >> Thanks in advance for the help,
> >>
> >> Paul
> >>
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-- 

Keith Hoard
Collierville, TN
khoard at gmail.com
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