"Miracle switch" failures
wgalligan
wgalligan at cnbcom.net
Thu Mar 27 11:33:05 AKST 2003
THANKS Gene, thats just what I wanted to hear. For me one battery, one switch...go fly probably wont happen agian in a thousand flights. Just a different gremlin next time (fingers crossed).
With that I am going to let this post die.
Wayne
> The problem with redundant batteries is that unless you put something
> between the two circuits to isolate them, it is possible for one of the
> batteries to go bad (shorted cell) and actually drain the other battery.
>
> There are battery backup systems available. I believe this is what they do,
> a backup battery is isolated from the main source. If the main source goes
> below some point, it is switched off and the backup is then switched on. So,
> in this case, the backup is never actually being used until there is a
> failure in the main battery. There in lies the problem, the backup is never
> being exercised. Unless you cycle it periodically you won't know it's going
> south until it's to late.
>
> Plus, you just put something else in the system that can fail! K.I.S.S.
>
> Gene Maurice
> gene.maurice at attbi.com
> Plano, TX
> AMA 3408
> NSRCA 877
>
>
>
> -----Original Message-----
> From: discussion-request at nsrca.org
> [mailto:discussion-request at nsrca.org]On Behalf Of wgalligan
> Sent: Thursday, March 27, 2003 12:51 PM
> To: discussion at nsrca.org
> Subject: Re: "Miracle switch" failures
>
>
> I range checked just proIr to take off and everything was great. Your right
> it had to just be the voltage flash off prior to the battery settling down
> on the voltage load. There is no way to test for this unless you disconnect
> the lead form the receiver. As I had checked the battery just prior to take
> off, 6.5v on the ESV. This one however is putting out some voltage and is
> not low enough like in the cases Jim has heard of.
>
> I was just reading a big article Jim wrote about servo equalizers(like
> matchboxs) and switching. Some people have gone as far as splitting
> batteries and going to double switches and packs. You could easily do this
> since I was running 1650mil NiMh pack. Just go to two 750mil or 800 mil
> packs and two switches for the absolute in redundancy. There would not be
> much of a weight penalty. But then there you go... adding more equipment
> to your airplane and doubling the potential for something to goof up. Like
> forgetting to charge one of the batteries.
>
> Does the voltage low meter work between the switch and receiver? If it does
> this would have alerted me to the problem.
>
> Wayne
>
> > You are right. The regulator is bad. Jim Oddino thinks this is unlikely
> > to happen in the air. My experience concurs. It could fail during use,
> > but is more likely to fail on powerup. Therefore it is likely that the
> > failure occurred on the ground, but was not evident until the charge flash
> > burned off. No way you could have checked for this, is there?
> >
> > I have a Voltwatch on my Entropy and have used it on all non-canopy
> > planes. This would tell you about a voltage low. Maybe we need to start
> > using them on the Aries too>
> >
> > --Lance
> >
> >
> >
> >
> > wgalligan
> > <wgalligan at cnbco To: Lance
> VanNostrand/249603/US/EKC at Kodak
> > m.net> cc:
> > Subject: Re: "Miracle
> switch" failures
> > 03/27/03 10:47
> > AM
> >
> >
> >
> >
> >
> >
> >
> > yes... with no load it is at 5.97v normal but with just my ESV on it it
> > only shows 4.2v.
> > certainly the load of an ESV shouldnt trick the regulator to drop the
> > voltage that low.
> >
> >
> > > So, you are saying that the voltage after the regulator (at the
> receiver)
> > > was fine with no load,but dropped to 4.4v wiht a load. What load did
> you
> > > apply?
> > >
> > > ----- Forwarded by Lance VanNostrand/249603/US/EKC on 03/27/03 10:06 AM
> > > -----
> > >
> >
> > > wgalligan
> >
> > > <wgalligan at cnbcom To:
> > "discussion at nsrca.org" <discussion at nsrca.org>
> > > .net> cc:
> >
> > > Sent by: Subject: Re: "Miracle
> > switch" failures
> > > discussion-reques
> >
> > > t at nsrca.org
> >
> > >
> >
> > >
> >
> > > 03/25/03 12:30 PM
> >
> > > Please respond to
> >
> > > discussion
> >
> > >
> >
> > >
> >
> > >
> > >
> > >
> > >
> > > I tested battery hooked to the switch and off the switch. Check voltage
> > on
> > > the input side of battery with VOM while expanded meter was hooked to
> > > output side. IN all cases the battery was at 6.5+v. the output when
> > > checked with just the VOM was 5.97v(normal) but when I hooked up a
> loaded
> > > meter the voltage dropped to 4.2v when th e inout was at 6.5.
> > > When the battery had a fresh charge the output was like 4.4v just enough
> > to
> > > get it in the air and after a littel discharge it had to be dropping
> > below
> > > the recievers voltage threshold.
> > >
> > > Anyway.... off to finish building the new one.
> > >
> > > Wayne
> > >
> > > > First of all the electronic "switch" is a device used in a linear mode
> > > when
> > > > regulating. If the input voltage drops below the set regulated
> voltage
> > > it
> > > > will saturate and if it is a good regulator will have an on resitance
> > of
> > > 50
> > > > milliohms or so. I didn't hear if he checked the input voltage under
> > the
> > > > same conditions he measured 4.2 volts on the output. Either the input
> > > > voltage was low or the on resistance was high and/or the load current
> > was
> > > > too high.
> > > > Second, the electronic switch/regulator is not in parallel or tandem
> > with
> > > > the mechanical switch. If the mechanical switch fell off the plane
> you
> > > > would not lose power. In fact I don't even have a mechanical switch
> on
> > > my
> > > > new plane. I use a safeing plug to turn it off.
> > > > The device I use protects itself and I wouldn't know how to make it
> > fail
> > > > within its rated operating conditions. You can put a dead short on
> the
> > > > output and not hurt anything. Try that with your mechanical switch
> but
> > > have
> > > > a fire extinguisher handy.
> > > > Think about how long the old mechanical tuners on TVs lasted. When
> was
> > > the
> > > > last time you heard of an electronic tuner going bad? I rest my case.
> > > > Jim
> > > > ----- Original Message -----
> > > > From: "John Ferrell" <johnferrell at earthlink.net>
> > > > To: <discussion at nsrca.org>
> > > > Sent: Tuesday, March 25, 2003 6:24 AM
> > > > Subject: Re: "Miracle switch" failures
> > > >
> > > >
> > > > > If I understand the failure conditions, the electronic switch was
> > > > paralleled
> > > > > with a mechanical switch.
> > > > > That is not something that would be considered a 'normal'
> > configuration
> > > > for
> > > > > the electronic switch.
> > > > > I refrain from using these devices because I have never had a switch
> > > > problem
> > > > > with a Futaba switch.
> > > > > Most electronic power switching devices that I am aware of are
> MOSFET
> > > > > technology.
> > > > > These devices switch many amps with great reliability, but are
> > > extremely
> > > > > vulnerable to voltage spikes.
> > > > > The inputs and outputs are protected by internal diodes from these
> > > spikes.
> > > > > I have been unable to puzzle out if there is an unprotected
> > > input-output
> > > > > junction.
> > > > > Here is a possible scenario:
> > > > > The mechanical switch is turned off generating a spike that
> > damages
> > > > the
> > > > > elecronic switch in a failure
> > > > > mode that drags down the receiver voltage feed.
> > > > > My personal conclusion is that either switch will work as
> advertised,
> > > but
> > > > > when used in tandem it is
> > > > > not a matter of if it will fail but when it will fail.
> > > > >
> > > > > John Ferrell
> > > > > 6241 Phillippi Rd
> > > > > Julian NC 27283
> > > > > Phone: (336)685-9606
> > > > > Dixie Competition Products
> > > > > NSRCA 479 AMA 4190 W8CCW
> > > > > "My Competition is Not My Enemy"
> > > > >
> > > > >
> > > > >
> > > > > ----- Original Message -----
> > > > > From: <s.vannostrand at kodak.com>
> > > > > To: <discussion at nsrca.org>
> > > > > Sent: Monday, March 24, 2003 1:16 PM
> > > > > Subject: "Miracle switch" failures
> > > > >
> > > > >
> > > > > > I know there are some vendors and users of those voltage
> regulators
> > > with
> > > > > > the built in switch. One mfg calls it the miracle switch. I have
> > > one,
> > > > > > hooked it up, am using it with no problems so far, but I may be
> > just
> > > > > lucky.
> > > > > > Is there a right/wrong way to hook up the connectors? I have a
> > radio
> > > > > south
> > > > > > one and there are two male connectors (one for the receiver, and
> > one
> > > for
> > > > > > recharging), and one female (for the battery input). The system
> > > works
> > > > > with
> > > > > > either male plugged into the receiver. Based on Wayne's sad story
> > > below
> > > > > > I'm wondering if maybe only one should be connected to the
> receiver
> > > in
> > > > > > order to maintain voltage when the switch fails.
> > > > > >
> > > > > > Anyone know if there is a sure way to tell if you have it hooked
> up
> > > > > > correctly?
> > > > > >
> > > > > >
> > > > > > Wayne writes, " I am/was using a MCI Miracle switch that is a
> > > regulator
> > > > > and
> > > > > > has fail safe if the mechanical switch contacts fail the switch
> > stays
> > > on
> > > > > > all the time. I tested the battery and it checked at 6.5v. I
> > > checked
> > > > > > through the charge port and 6.5v. But when I checked it through
> > the
> > > > > > connector to the receiver it only registered 4.25v just below the
> > > > > > receivers voltage threshold. "
> > > > > >
> > > > > > --Lance
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > =====================================
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> > >
> > >
> > >
> > >
> > >
> >
> >
> >
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> >
> >
> >
> >
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