[NSRCA-discussion] Reducing the odds... - Now Cooling
Earl Haury
ehaury at houston.rr.com
Tue Mar 28 11:32:38 AKST 2006
Didn't get that far - a jury summons does provide the opportunity to sit
quietly for several hours - good time to think about pattern stuff.
Earl
----- Original Message -----
From: "Michael Wickizer" <mwickizer at msn.com>
To: <nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, March 28, 2006 1:47 PM
Subject: Re: [NSRCA-discussion] Reducing the odds... - Now Cooling
> Another good jurist overlooked...was it your stance on the death penalty
> or
> perhaps your response to preferred methods of execution?
>
>>From: "Earl Haury" <ehaury at houston.rr.com>
>>Reply-To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
>>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>Subject: Re: [NSRCA-discussion] Reducing the odds... - Now Cooling
>>Date: Tue, 28 Mar 2006 13:12:28 -0600
>>
>>
>>The foam cup trick works in some airplanes - fine in my E-Partner. Others,
>>like the Abbra, present some problems with motor cooling. It's not easy to
>>determine airflow into / inside the fuse - I played with smoke a bit to
>>observe flows, but with limited success. As Dean points out - high
>>pressure
>>air in contact with the item to be cooled is the way to go. The foam
>>"filler" is an easy way to achieve this - any air entering the ducts must
>>flow over the motor, there's no other route.
>>
>>An added function of the foam is a low weight way to strengthen the fuse
>>nose, some designs have little strength forward the normal firewall
>>location. Of course this is where we need to mount the motor. The foam
>>also
>>reduces gear noise.
>>
>>Hopefully there're a couple of pics attached of the Abbra installation.
>>The
>>large hole in the bottom of the foam aligns with a baffle in the chin.
>>Note
>>also that the Comp motor is longer than the regular C50, so it protrudes
>>from the rear mount (which actually forces some of the air through the
>>spiral fins on the motor).
>>
>>Earl
>>
>>
>>----- Original Message ----- From: "Michael Wickizer" <mwickizer at msn.com>
>>To: <nsrca-discussion at lists.nsrca.org>
>>Sent: Tuesday, March 28, 2006 9:54 AM
>>Subject: Re: [NSRCA-discussion] Reducing the odds...
>>
>>
>>>Nat:
>>>
>>>Not nearly as sexy or professional as Earl's solution, but I know
>>>somebody
>>>that has used styrafoam coffee cups cut to size and glued in with CA.
>>>Proved to be very effective and a quick install.
>>>
>>>Mike
>>>
>>>
>>>>From: "Nat Penton" <natpenton at centurytel.net>
>>>>Reply-To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
>>>>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>>Subject: Re: [NSRCA-discussion] Reducing the odds...
>>>>Date: Mon, 27 Mar 2006 17:08:27 -0600
>>>>
>>>>Earl
>>>>Can you provide more detail on the ducts ? Nat
>>>>
>>>>----- Original Message -----
>>>>From: "Earl Haury" <ehaury at houston.rr.com>
>>>>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>>Sent: Monday, March 27, 2006 4:07 PM
>>>>Subject: Re: [NSRCA-discussion] Reducing the odds...
>>>>
>>>>
>>>> > Jim
>>>> >
>>>> > I've used the datalogger to monitor in-flight performance quite a
>>>> > bit.
>>>> > Typically, during a P-07 flight the low voltage stays above 35v
>>>> > (typically
>>>> > <65A max) and power consumption is in the range of 3000 to 3400 mAh
>>>> > (depending on wind) for an eight minute flight. I've set the ESC min
>>>>volts
>>>> > /
>>>> > cell to 3.0v, but 3.3 would work. These numbers are similar with APC
>>>> > 20x15,
>>>> > 21x14, and 21x13W E props - Hacker C50XL-14 motor.
>>>> >
>>>> > Be observant of motor heating in the Abbra, I saw some pretty high
>>>>numbers
>>>> > with "typical" baffles. Filled the nose with foam (wing core type),
>>>>bored
>>>> > a
>>>> > "tunnel" for the motor, and hot wired ducts. Motor stays very cool
>>>>now.
>>>> >
>>>> > Earl
>>>> >
>>>> >
>>>> >
>>>> >
>>>> > ----- Original Message -----
>>>> > From: "J.Oddino" <joddino at socal.rr.com>
>>>> > To: <chad at f3acanada.org>; "NSRCA Mailing List"
>>>> > <nsrca-discussion at lists.nsrca.org>
>>>> > Sent: Monday, March 27, 2006 1:16 PM
>>>> > Subject: Re: [NSRCA-discussion] Reducing the odds...
>>>> >
>>>> >
>>>> >> Hi Chad,
>>>> >>
>>>> >> I'm about to launch my first electric pattern plane and I'd like to
>>>> >> get
>>>> >> your
>>>> >> opinion on my logic for setting the cutoff voltage. First of all
>>>> >> I'd
>>>> >> prefer
>>>> >> that I'd never let any cell get below 3.3 volts per cell. However,
>>>> >> I'd
>>>> >> also
>>>> >> prefer that the motor never stopped. My plan is to get to know the
>>>> >> battery
>>>> >> voltage vs. flight profile to accomplish both. I will set the
>>>> >> cutoff
>>>> >> voltage very low so it will never cut the motor. I will telemeter
>>>>the
>>>> >> voltage and current and keep track of the mAh consumed. If I see
>>>> >> the
>>>> >> voltage getting too low (<33V)under max load or use more than 80% of
>>>>the
>>>> >> capacity I will land. If I can't get through the pattern I'll >>
>>>>probably
>>>> >> need
>>>> >> to go to a smaller prop. Once I am confident that the profile is
>>>> >> consistent
>>>> >> I can remove the TM system. What do you think?
>>>> >>
>>>> >> Jim O
>>>> >>
>>>> >> ----- Original Message -----
>>>> >> From: "Chad Northeast" <chad at f3acanada.org>
>>>> >> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>> >> Sent: Sunday, March 26, 2006 10:45 AM
>>>> >> Subject: Re: [NSRCA-discussion] Reducing the odds...
>>>> >>
>>>> >>
>>>> >>> Hi Eric,
>>>> >>>
>>>> >>> Regardless of cutoff, its the resting voltage that is of paramount
>>>> >>> importance for good pack life. A 1C discharge with a 3V/cell
>>>> >>> cutoff
>>>> >>> will leave you with a very low resting voltage, as compared to a
>>>> >>> 15C
>>>> >>> discharge with the same cutoff. Recently there has been a number
>>>> >>> of
>>>> >>> discussions about increasing safe cutoff values as the C rates go
>>>> >>> up
>>>> >>> since most of the current packs hold voltage so well up until then
>>>> >>> end
>>>> >>> when they simply dump everything they have....so 3 v/cell now
>>>> >>> equals
>>>>to
>>>> >>> a much deeper discharge than in the past.
>>>> >>>
>>>> >>> Then there is the problem that the ESC is only seeing average pack
>>>> >>> voltage and not cell voltage...so its entirely possible while under
>>>> >>> discharge to have a pair of cells at 3.2v (6.4 total) and the third
>>>> >>> at
>>>> >>> 9-6.4....or 2.6V, and now your ESC will cut properly...but that one
>>>>cell
>>>> >>> is being damaged.
>>>> >>>
>>>> >>> If you run a bit higher cutoff (3.1-3.2) and fly so that your open
>>>> >>> circuit resting voltage is 3.75-3.8 you will have very happy
>>>>batteries.
>>>> >>>
>>>> >>> I agree...there is not enough of this information available without
>>>>a
>>>> >>> lot of online reading. There is a lot of this on RC >>>
>>>>Groups...although
>>>> >>> it can take a significant amount of time to wade through the BS and
>>>> >>> gather what is useful.
>>>> >>>
>>>> >>> Chad
>>>> >>>
>>>> >>> Grow Pattern wrote:
>>>> >>>
>>>> >>> >Chad,
>>>> >>> > The speed controller cuts out at 9V. It actually drops
>>>> >>> > to
>>>> >>> > about
>>>> >>> >8.3V under load and then settles back to 9.0V after the motor
>>>> >>> >cuts.
>>>> >>> >
>>>> >>> >You know it's not so much that I am reporting what I personally do
>>>> >>> >as
>>>> >> much
>>>> >>> >more like I am stating what the system does.
>>>> >>> >
>>>> >>> >The voltage cut-off end-user value options on the speed controller
>>>>are
>>>> >>> >selectable but still have fixed values. A three-cell pack has to
>>>>use
>>>> >>> >the
>>>> >>> >9.0V option. I used my in-line meter to monitor and measure these
>>>> >> results.
>>>> >>> >
>>>> >>> >Once again we are back to the instructions verses acquired >>>
>>>> >knowledge!
>>>> >>> >
>>>> >>> >Regards,
>>>> >>> >
>>>> >>> >Eric.
>>>> >>> >
>>>> >>> >
>>>> >>> >----- Original Message -----
>>>> >>> >From: "Chad Northeast" <chad at f3acanada.org>
>>>> >>> >To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>> >>> >Sent: Sunday, March 26, 2006 10:30 AM
>>>> >>> >Subject: Re: [NSRCA-discussion] Reducing the odds...
>>>> >>> >
>>>> >>> >
>>>> >>> >
>>>> >>> >
>>>> >>> >>>I now believe that I had a bad cell on the one that blew-up.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>If you were discharging to 3 v/cell as I read it from your data
>>>> >>> >>then
>>>> >>> >>its
>>>> >>> >>not surprising that you would have bad cells....a 3v/cell resting
>>>> >>> >>would
>>>> >>> >>indicate that you are discharging much below that under load.
>>>> >>> >>
>>>> >>> >>shoot for 3.7-3.8 v/cell resting (5-10 minutes) after the flight
>>>> >>> >>and
>>>> >>> >>your batteries will be much happier, and stay in balance all by
>>>> >>> >>themselves for the most part.
>>>> >>> >>
>>>> >>> >>Chad
>>>> >>> >>
>>>> >>> >>
>>>> >>> >>Grow Pattern wrote:
>>>> >>> >>
>>>> >>> >>
>>>> >>> >>
>>>> >>> >>>First of all thanks for all of the suggestions and advice from
>>>>the
>>>> >>> >>>list
>>>> >>> >>>surrounding the charging of my Lipo's.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>I have been messing with the big Lipo's since before Jason flew
>>>> >>> >>>his
>>>> >> most
>>>> >>> >>>notable entry at the world's four years ago. This was my first
>>>> >>> >>>catastrophic
>>>> >>> >>>failure of a battery pack. I have spent around $7000 on
>>>> >>> >>>electrics
>>>>in
>>>> >> that
>>>> >>> >>>period of time and have closely monitored their technical
>>>> >>> >>>development.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Right now I am working on sport type or sport level electrics.
>>>>Not
>>>> >>> >>>the
>>>> >>> >>>foamy
>>>> >>> >>>type or super light type of models, but the alternatives to 40
>>>>sized
>>>> >> glow
>>>> >>> >>>motor powered models.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>I particularly like the HIMAX offerings where they sell a motor,
>>>>a
>>>> >> motor
>>>> >>> >>>mount, a matching speed controller and a prop all in one box.
>>>>This
>>>> >> saves a
>>>> >>> >>>lot of guessing and previous trial and error on the part of the
>>>> >>> >>>buyer.
>>>> >> You
>>>> >>> >>>are left with the choice of what battery pack and what plane to
>>>> >>> >>>put
>>>> >>> >>>it
>>>> >> in.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Which brings us back to the exploding Thunderpower 4400 pack. I
>>>> >>> >>>had
>>>> >> been
>>>> >>> >>>using my Astroflight 109 chargers with great success. I have 4
>>>> >>> >>>of
>>>> >>> >>>them.
>>>> >>> >>>This
>>>> >>> >>>was before the little add-on balancers were available. They >>>
>>>> >>>charged
>>>>a
>>>> >>> >>>bunch
>>>> >>> >>>of different packs up to and including the big 4S3P packs with
>>>> >>> >>>no
>>>> >> problems
>>>> >>> >>>etc. I am familiar with their warning etc. In particular, it >>>
>>>> >>>states
>>>> >> that
>>>> >>> >>>it
>>>> >>> >>>is not recommenced to charge a fully charged pack, (note: not
>>>> >> forbidden).
>>>> >>> >>>It
>>>> >>> >>>further states that the charger will shut down the charge after
>>>>about
>>>> >>> >>>4
>>>> >>> >>>minutes if you actually try and do this.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Now we get to the 3S pack in question. I was not satisfied with
>>>> >>> >>>the
>>>> >>> >>>knowledge of what happened and the comfort of how to prevent it
>>>> >> happening
>>>> >>> >>>again. I did not have another pack, or at least I was not going
>>>>to
>>>> >>> >>>risk
>>>> >> an
>>>> >>> >>>old friend's second and last pack. I did a couple of things.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>I measured the each cell of my 3600 mAh Tanic's using the
>>>> >>> >>>voltage
>>>> >>> >>>taps
>>>> >>> >>>that
>>>> >>> >>>are part of the assembled pack.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>CELL UP CELL DOWN
>>>> >>> >>>
>>>> >>> >>>I 4.18 3.01
>>>> >>> >>>
>>>> >>> >>>II 4.18 3.00
>>>> >>> >>>
>>>> >>> >>>III 4.19 3.01
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Charging the pack when at 9.2V gave-
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>CELL UP
>>>> >>> >>>
>>>> >>> >>>I 4.18
>>>> >>> >>>
>>>> >>> >>>II 4.19
>>>> >>> >>>
>>>> >>> >>>III 4.18
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Charging the pack when fully charged caused the charged to read
>>>>it
>>>>as
>>>> >>> >>>3
>>>> >>> >>>cells. It went through the 3 minute determination pause.
>>>> >>> >>>Charged
>>>>for
>>>> >>> >>>about
>>>> >>> >>>a minute and said "I'm done!" did this with two different 3600
>>>>mAh
>>>> >> packs.
>>>> >>> >>>The charger did what it said it would do.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Then just as an FYI, I flew the model with both packs wired in
>>>> >> parallel.
>>>> >>> >>>One
>>>> >>> >>>pack was giving me 5 minutes of flight at full throttle. I
>>>> >>> >>>needed
>>>> >>> >>>more
>>>> >>> >>>air-time on the sport plane. (World models Sky Raider). I now
>>>> >>> >>>had
>>>>10
>>>> >>> >>>minutes
>>>> >>> >>>plus and the flight did not run out of steam.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>The two packs were fully charged and the plane flown for about
>>>>seven
>>>> >>> >>>minutes.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>This created a 3S2P pack. The readings were very encouraging.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>PACK-A
>>>> >>> >>>
>>>> >>> >>>CELL UP CELL PARTIALLY DOWN
>>>> >>> >>>
>>>> >>> >>>I 4.18 3.68
>>>> >>> >>>
>>>> >>> >>>II 4.18 3.68
>>>> >>> >>>
>>>> >>> >>>III 4.17 3.67
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>PACK-B
>>>> >>> >>>
>>>> >>> >>>CELL UP CELL PARTIALLY DOWN
>>>> >>> >>>
>>>> >>> >>>I 4.18 3.68
>>>> >>> >>>
>>>> >>> >>>II 4.19 3.68
>>>> >>> >>>
>>>> >>> >>>III 4.18 3.67
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>The cells were discharging and charging nice and equally.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>My charging practices have been upgraded to.
>>>> >>> >>>
>>>> >>> >>>1. Test voltage of each cell before each charge.
>>>> >>> >>>
>>>> >>> >>>2. Monitor the charge initiation.
>>>> >>> >>>
>>>> >>> >>>3. Place pack on 1/2" metal plate on table outside of van. (Deep
>>>> >>> >>>Cycle
>>>> >>> >>>marine 12V is in back of van).
>>>> >>> >>>
>>>> >>> >>>4. Check reading periodically.
>>>> >>> >>>
>>>> >>> >>>5. Test voltage of each cell after each charge.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>I now believe that I had a bad cell on the one that blew-up. I
>>>> >>> >>>also
>>>> >> would
>>>> >>> >>>not charge the TP pack without the after-market device. In fact
>>>> >>> >>>I
>>>>now
>>>> >> do
>>>> >>> >>>anything to reduce the odds of another accident.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Just looking at the display on the 109 charger tells you a lot.
>>>> >>> >>>The
>>>> >> number
>>>> >>> >>>cells, the voltage during initialization and during charge, must
>>>> >>> >>>be
>>>> >>> >>>correct,
>>>> >>> >>>or at least in range. Putting the pack in a fire safe place is
>>>> >> paramount.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Regards,
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>Eric.
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>_______________________________________________
>>>> >>> >>>NSRCA-discussion mailing list
>>>> >>> >>>NSRCA-discussion at lists.nsrca.org
>>>> >>> >>>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>>
>>>> >>> >>_______________________________________________
>>>> >>> >>NSRCA-discussion mailing list
>>>> >>> >>NSRCA-discussion at lists.nsrca.org
>>>> >>> >>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>> >>> >>
>>>> >>> >>
>>>> >>> >>
>>>> >>> >
>>>> >>> >_______________________________________________
>>>> >>> >NSRCA-discussion mailing list
>>>> >>> >NSRCA-discussion at lists.nsrca.org
>>>> >>> >http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>> >>> >
>>>> >>> >
>>>> >>> >
>>>> >>> _______________________________________________
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>>>> >>>
>>>> >>>
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>>>> >>> Version: 7.1.385 / Virus Database: 268.3.2/293 - Release Date:
>>>>3/26/2006
>>>> >>>
>>>> >>
>>>> >> _______________________________________________
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>>>> >> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>> >>
>>>> >
>>>> >
>>>> > _______________________________________________
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>>>> > http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>> >
>>>> >
>>>> >
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>>>> > Checked by AVG Free Edition.
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>>>> >
>>>> >
>>>>
>>>>
>>>>
>>>>--
>>>>Internal Virus Database is out-of-date.
>>>>Checked by AVG Free Edition.
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>>>
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>
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>
>><< Foam-2.jpg >>
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