Today's Message Index:
----------------------
1. 05:03 AM - Re: Photo needed (Robert L. Nuckolls, III)
2. 10:16 AM - Re: Re: DIY CBOVM: variations on a theme (Jan de Jong)
3. 11:13 AM - Re: Re: DIY CBOVM: variations on a theme (Robert L. Nuckolls, III)
4. 01:02 PM - Re: Re: DIY CBOVM: variations on a theme (Jan de Jong)
5. 03:42 PM - Re: Photo needed (Robert L. Nuckolls, III)
6. 04:24 PM - Re: Re: DIY CBOVM: variations on a theme (Robert L. Nuckolls, III)
7. 06:00 PM - Simple Diode Tester (Eric M. Jones)
8. 09:04 PM - Re: Simple Diode Tester (Jeff B.)
Message 1
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| Subject: | Re: Photo needed |
At 07:29 PM 3/27/2014, you wrote:
><nuckolls.bob@aeroelectric.com>
>
>I'm needing a nose-on picture of an OBAM aircaft
>for use on the counter display for the AEC9012
>programmable wig-wag at Osh . . .
Thanks to all who have contributed to this
call for photos! I've received some very nice
suggestions . . . some of which are excellent
candidates for the cover of R13.
It has been suggested that I clarify my
original request. I'm crafting a counter-top
display for the AEC9012 programmable wig-wag.
I'd like have a full wing span, nose-on view
of an airplane on which I'll mount white leds
out on the wings . . . and paste the whole over
a background that emulates an in-flight scenario.
Hence, the photo need not . . . be of an airplane
in flight, sitting on the ground would be just
fine. Preferably a tricycle gear so that the
tail feathers are disposed in a 'level flight'
position to the nose.
Bob . . .
Message 2
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| Subject: | Re: DIY CBOVM: variations on a theme |
That's another issue with a lithium battery - it does not keep OV down
well - even if not fitted with a BMS. And it seriously dislikes
overvoltage. It thus requires a fast OV switch at the alternator.
And if it has a BMS it will also have a battery OV cutoff switch built
in. Making the battery unavailable just when it is needed.
My conclusion has been that if I want Lithium I will have to make the
under/over cell voltage and cell temperature monitoring and top
balancing myself.
With backed up OV protection at the alternator.
And have the individual cells accessible to thermistors.
Jan de Jong
On 3/26/2014 8:45 PM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 11:45 AM 3/26/2014, you wrote:
>>
>> In regards to stability you might check that there is a capacitor
>> across the voltage reference diode and another from the SCR gate to
>> ground. If you happen to have an old circuit diagram dated before
>> about 2005 it may not show that update.
>>
>> One nice thing about the crowbar and circuit breaker in the Z
>> diagrams is that the voltage is brought under control immediately
>> when the SCR fires. If I understand your post it sounds like your
>> implementation waits for the relay to open and for any subsequent
>> arcing to extinguish. Perhaps that is good enough but it seems
>> preferable to use the circuit breaker as per the Z diagrams so that
>> the SCR clamps the voltage faster. Might be other small advantages as
>> well such as a subsequent dead battery could not cause the alternator
>> to come back on line.
>
> For the run-of-the-mill ov conditions with a good
> battery, an ov even is not one of extreme urgency.
> The ships air-worthy battery will stand off a runaway
> alternator for significant intervals. If one waited
> 100 mS to evaluate an ov condition for a true runaway
> alternator, it wouldn't be a bad thing.
>
> In fact, the next generation ov module will do just
> that. Sensing an ov condition start a 100mS timer
> that continue to run as long as the voltage does not
> drop back below 16V before the timer runs out.
>
> On the other hand, a second threshold at 20V assumes
> no air worthy battery is present and an immediate trip
> is initiated.
>
> We're still going to pull down on the field supply
> breaker . . .
>
>
> Bob . . .
>
>
Message 3
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| Subject: | Re: DIY CBOVM: variations on a theme |
At 12:15 PM 3/31/2014, you wrote:
>
>That's another issue with a lithium battery - it does not keep OV
>down well - even if not fitted with a BMS. And it seriously dislikes
>overvoltage. It thus requires a fast OV switch at the alternator.
>And if it has a BMS it will also have a battery OV cutoff switch
>built in. Making the battery unavailable just when it is needed.
>
>My conclusion has been that if I want Lithium I will have to make
>the under/over cell voltage and cell temperature monitoring and top
>balancing myself.
>With backed up OV protection at the alternator.
>And have the individual cells accessible to thermistors.
Your perceptions of being inadequately informed
with respect to operating details of the various
lithium products are accurate.
There is no industry standard for the term "BMS".
I'm working the 4th installment on the series
of battery articles for Kitplanes. The past 7
weeks have been enlightening.
I'm not sure that alternator OV protection needs
to be anything beyond the ordinary . . . I'm still
stirring the stew of simple-ideas . . .
Bob . . .
Message 4
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| Subject: | Re: DIY CBOVM: variations on a theme |
The implicit "trust us" attitude is in any case unwarranted. Full
specifications of the built-in electronics are absolutely necessary.
What I have seen is not very compatible with aircraft use. We do not
want OV cut-out built-in (should be done somewhere up in the charging
path). We probably do not want LV cut-out built-in either (saving the
battery may not always be the highest goal). But we want monitoring and
warning. And as a pilot I want to know about temperatures. When used
well (correct voltages and currents within limits, no recharging ever
after full discharge) the remaining danger is a manufacturing fault,
with temperature discrepancy the only available signal.
And a measure of top balancing is needed unless we are willing to adopt
a discipline of doing that externally. A certain minimum balancing
current per Ah, say 50mA or so is required. I've seen balancing currents
quoted for Chinese BMS products that are likely useless for any
realistic battery size (they may be intended for UPS batteries - very
long charging times and smallish charging currents).
And the balancing algorithm is often primitive - most balancers only
balance at the very end of the charging process by comparing a cell
voltage with a high limit-voltage, not during the charging process by
comparing a cell voltage with the voltages of other cells. The latter
allows good balancing with a lower alternator set voltage. In exchange
for a few percent of charge you get much longer life - apparently.
I wish you wisdom with the 4th article on batteries (great articles so
far, I approve of the current editor in chief of KP!)
Jan de Jong
On 3/31/2014 8:12 PM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 12:15 PM 3/31/2014, you wrote:
>> <jan_de_jong@casema.nl>
>>
>> That's another issue with a lithium battery - it does not keep OV
>> down well - even if not fitted with a BMS. And it seriously dislikes
>> overvoltage. It thus requires a fast OV switch at the alternator.
>> And if it has a BMS it will also have a battery OV cutoff switch
>> built in. Making the battery unavailable just when it is needed.
>>
>> My conclusion has been that if I want Lithium I will have to make the
>> under/over cell voltage and cell temperature monitoring and top
>> balancing myself.
>> With backed up OV protection at the alternator.
>> And have the individual cells accessible to thermistors.
>
> Your perceptions of being inadequately informed
> with respect to operating details of the various
> lithium products are accurate.
>
> There is no industry standard for the term "BMS".
> I'm working the 4th installment on the series
> of battery articles for Kitplanes. The past 7
> weeks have been enlightening.
>
> I'm not sure that alternator OV protection needs
> to be anything beyond the ordinary . . . I'm still
> stirring the stew of simple-ideas . . .
>
>
> Bob . . .
>
Message 5
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At 03:40 PM 3/31/2014, you wrote:
>Bob,
>
>I couldn't find a plain front on shot that was suitable. I don't
>suppose the attached would be any good though?
>
>All the shots I sent are my own work.
Yes! That will work!
Thanks.
Unless you're submitting candidate photos for R13
front cover, know that Ed has nicely filled my needs
for the AEC9012 wig-wag display.
We're still compiling a library of R13 Cover
photos. Just as we did last time, I'll probably
pick 5 or 6 from what's offered and the AeroElectric-List
members will pick the winner.
Thanks to all who assisted with the current
project.
Bob . . .
Message 6
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| Subject: | Re: DIY CBOVM: variations on a theme |
At 03:00 PM 3/31/2014, you wrote:
The implicit "trust us" attitude is in any case unwarranted. Full
specifications of the built-in electronics are absolutely necessary.
that will be a primary premise of the 'last' article.
What I have seen is not very compatible with aircraft use. We do not
want OV cut-out built-in (should be done somewhere up in the charging path).
This is certainly the legacy philosophy for lead-acid
and/or Ni-Cad batteries wherein the battery was a
'current sink' of demonstrable value for managing
a runaway generator/alternator.
But let's assume for the moment that one of our
future design goals is to craft and prove airworthiness
of an alternator-only operation protocol. Now we need
to show that the runaway alternator can be controlled
within the DO160/MilSTD704 envelope.
If that proves to be practical, then the electronics
in the battery need not assume any duties beyond those
for protecting the battery . . . the battery MIGHT be
relieved of duty for standing guard at the gates
standing off runaway alternators.
We probably do not want LV cut-out built-in either (saving the
battery may not always be the highest goal). But we want monitoring
and warning.
Yeah . . . but it depends on WHERE the l.v. cutout
occurs.
Toyota writes software intended to maintain their
lithium cells at some place between 30 and 85% capacity.
This is the ENERGY operating range that offers the
advertised cell life. But they don't force disconnect
the battery . . . as far as I've been able to learn
so far.
Depending on the BMS designer's charter from on-high . . .
he may well have other bounds. Without advocating for
any particular energy range . . . I'll suggest that any
offering that includes a BMS would do well to tell
all . . . inquiring pilots NEED to know.
And as a pilot I want to know about temperatures. When used well
(correct voltages and currents within limits, no recharging ever
after full discharge) the remaining danger is a manufacturing fault,
with temperature discrepancy the only available signal.
And a measure of top balancing is needed unless we are willing to
adopt a discipline of doing that externally. A certain minimum
balancing current per Ah, say 50mA or so is required. I've seen
balancing currents quoted for Chinese BMS products that are likely
useless for any realistic battery size (they may be intended for UPS
batteries - very long charging times and smallish charging currents).
Exactly. An these issues drive cost of ownership. Yes,
the lithium products have stellar performance in some
venues but with LIMITS that much be UNDERSTOOD and
incorporated into the user's operating philosophy.
$time$ fiddling with batteries is $time$ not available
to go flying.
And the balancing algorithm is often primitive - most balancers only
balance at the very end of the charging process by comparing a cell
voltage with a high limit-voltage, not during the charging process by
comparing a cell voltage with the voltages of other cells. The latter
allows good balancing with a lower alternator set voltage. In
exchange for a few percent of charge you get much longer life - apparently.
"Apparently" is the operative term. The family
of lithium cells available for incorporation into
finished goods is not large . . . There's probably
no more than a half dozen shakers-n-movers in
the cylindrical cell market. They're all pretty
big names . . . I doubt that core capabilities
of the range of offerings varies much. But we
see a large variation in proposed operating
philosophies across the spectrum of "assemblers"
who package these cells up for market.
I wish you wisdom with the 4th article on batteries (great articles
so far, I approve of the current editor in chief of KP!)
Thank you my friend. I'm learning. But I wish that the
questions were being answered faster than they surface!
This first past at lithium-for-airplanes will probably
be disappointing for many who hope that a an ideal
drop-in-replacement for SVRLA is going to emerge.
But as you've noted, no matter what the advertising
hype says, "Their ain't no such thing as a lithium
drop-in for lead-acid."
For anything beyond the day-vfr machine with
gravity flow fuel and magnetos, the prudent
owner/pilot would do well to understand the
limitations. Further, assuming a willingness to
$invest$ in weight savings know that changes to
ownership and operating philosophy are inevitable.
Thank you for contributing to the dialog . . .
Bob . . .
Message 7
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| Subject: | Simple Diode Tester |
Simple Diode Tester.
Here is a simple diode tester you may find useful:
http://www.energpolarit.com/docs/muscletest_withdirect.pdf
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=421409#421409
Message 8
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| Subject: | Re: Simple Diode Tester |
Just think! If you apply this to anything experiencing interference on your
airplane, you can solve the problem! If you apply it to your airplane it
might become <gasp> invisible to radar!
So, how hard do we tap to wake the electrical system up?
-Jeff-
On Mon, Mar 31, 2014 at 6:59 PM, Eric M. Jones <emjones@charter.net> wrote:
> emjones@charter.net>
>
> Simple Diode Tester.
>
> Here is a simple diode tester you may find useful:
>
> http://www.energpolarit.com/docs/muscletest_withdirect.pdf
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones(at)charter.net
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=421409#421409
>
>
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