Today's Message Index:
----------------------
1. 07:31 AM - Battery Load Testing (Robert L. Nuckolls, III)
2. 07:34 AM - Re: Wiper motors question (Robert L. Nuckolls, III)
3. 07:38 AM - Re: Re: Alternators - To Fuse or not to fuse - That IS the question (Robert L. Nuckolls, III)
4. 07:52 AM - Re: Re: Alternators - To Fuse or not to fuse - That IS the question (Robert L. Nuckolls, III)
5. 08:12 AM - Re: Battery Load Testing (Roger)
6. 08:13 AM - Re: Re: Alternators - To Fuse or not to fuse - That IS the question (Robert L. Nuckolls, III)
7. 10:03 AM - Re: Battery Load Testing (Robert L. Nuckolls, III)
8. 03:22 PM - Re: Manual intercom PTT (Jeff Point)
9. 05:03 PM - Re: Manual intercom PTT (Peter Pengilly)
10. 05:36 PM - Re: Manual intercom PTT (Earl Schroeder)
Message 1
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| Subject: | Battery Load Testing |
At 11:20 AM 9/9/2017, you wrote:
>A few weeks (?) ago, Bob posted a link to a Harbor Freight 500 Amp
>Carbon Pile Load Tester:
>
><https://www.harborfreight.com/500-amp-carbon-pile-load-tester-91129.html>https://www.harborfreight.com/500-amp-carbon-pile-load-tester-91129.html
>
>I thought that this is what we would use to annually test the
>capacity of our batteries. I thought that we would connect the
>battery, set the amps to our expected load (for example, 12 amps)
>and then time how long until battery voltage reaches an unacceptably low level.
>
>But, upon reviewing the user manual for this tool, it does not look
>like that is what this thing is for. It appears to just load the
>battery for a short period of time and then extrapolate the battery
>condition based on how it behaves for that very short test period.
>
>What's the deal? How do we use this tool to check on our battery
>condition, annually?
It is one of TWO tests, and the least $time$ consuming
of the two. There are two qualities of a battery that
described its performance. One is internal resistance,
the ability to DELIVER what ever energy is contained
to the outside world. This quality goes to getting
the engine started and is loosely linked to overall
quality of the battery . . . a battery whose internal
resistance is rising is loosing active material . . .
active material is directly related to the second
quality of interest: CAPACITY.
To capcheck a battery, you need to literally run
it down with some load that approximates your
anticipated ENDURANCE requirements. Then track
how many minutes that load is supported. There
are test sets that do this automatically and give
you data plots.
Here's one such device
http://tinyurl.com/mas7ea9
I've had these in the shop for over a decade.
Very handy. This tool produces data plots like
this:
Emacs!
This was a new battery in installed in Dr. Dee's Saturn
just over two years ago. With a 5a load, it produced
just over 32 a.h. of energy output. I just replace that
battery yesterday . . . it had suffered a couple of run-down-
and-sit events . . . the worst thing you can do to a
battery. The new one is sitting in the garage with
a Battery Tender on it like my lab batteries.
The HF load tester is the quick'n dirty battery evaluator.
When you install a NEW battery. Make sure it's topped off
(Go flying for an hour). After landing, put the load tester
on, start the timer (15 seconds) and quickly crank the
knob up until the voltage FALLS to 9 volts. Adjust the
knob to maintain the 9v reading until the timer light
goes out. Then quickly observe and record the CURRENT
being delivered.
Repeating this test at intervals will reveal a slow
decline in that current reading. When it falls to 75%
of new, then about 1/4th of the battery's chemistry
has become inactive.
Now, if you subscribe to the legacy notion of replacement
at 75-80% of new capacity, then you know when to do it
based on this admittedly coarser measurement.
But if you'd care to do a ground check on ENDURANCE
then you need something like the West Mountain Radio
instrument -OR- you simply set up an ENDURANCE mode
load scenario in the hangar and watch a voltmeter. When
the voltage drops to 11.0 volts the battery is 90+
percent used up. If that TIME does not meet our exceed
your personal design goals for alternator-out operations,
THEN is when you replace the battery.
Bob . . .
Message 2
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| Subject: | Re: Wiper motors question |
At 11:06 AM 9/9/2017, you wrote:
>My guess (based on having used one as a trim motor) is that most of
>them are dumb motors governed by external inputs like limit switches
>and timers....BWTHDIK
Correct, these are just DC motors with two or more
speed select features (brushes offset from optimum
torque position) or taps on series field windings
(only in the nearly antique, electric motors).
There are numerous articles on the 'net for using
these motors in amateur robotics and other DIY
situations . . . they are cheap and robust . . .
but quite dumb. They have a servo-like behavior
in their ability to 'park' the wiper blades but
this is a simple limit switch mechanism.
Bob . . .
Message 3
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| Subject: | Re: Alternators - To Fuse or not to fuse - That |
IS the question
At 12:35 PM 9/9/2017, you wrote:
>Don,
>Thanks for the West Mountain CBA info. One possible problem I see
>with using the carbon pile is that the algorithms used to derive
>capacity are probably based on lead acid batteries, not LiFePO
>batteries. Aren't the discharge characteristics of Li batteries
>radically different from lead acid batteries?
Yes. You can use the load tester on LiPo but I'm
uncertain as to the target voltage for the test.
9v may be too low . . . but certainly 10v would
not hurt it.
The load test for battery performance is a COMPARATIVE
activity that looks as changes over time staring with
the new battery. You won't find useful data or algorithms
that equate load number to capacity values. This
is like using a dip stick in the oil pan . . . you
don't know the capacity of the pan . . . only how
much it has dropped from full.
Bob . . .
Message 4
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| Subject: | Re: Alternators - To Fuse or not to fuse - That |
IS the question
At 01:21 PM 9/9/2017, you wrote:
>The discharge characteristics are not dirrerent enough to cause a
>problem using the carbon pile. If you try the pile be careful, they
>get quite hot. I prefer to use the CBA, but it takes many hours to
>discharge to 10 volts.
Yes . . . because these are entirely different
kinds of tests. The carbon pile tester does get
hot . . . it will stink at the end of your test.
5-600 amps at 9v is 5400 watts . . . enough snort
to run your house. This energy is dumped into
that little stack of carbon disks.
http://tinyurl.com/ybcc9v9r
Emacs!
So yes, extending the test beyond 15 seconds
is probably not a good thing to do!
The CBA test gets you a whole different set
of data. It counts electrons under a specified
load (your ENDURANCE load) and measures the
time that load will be supported.
A much more precise measurement of the battery's
ability to perform in alternator-out conditions.
Another alternative is Z13/8. Here there is
no plan B that calls for tapping the battery
during main alternator out conditions. Hence,
you replace the battery at first sign of
sluggish cranking performance (the crudest
form of a load test).
This is why I've long suggested that Z13/8
is the lowest cost of ownership, highest
reliability system you can install on your
a/c. No test equipment, no preventative
maintenance, run the battery 'til it wheezes.
How much simpler can it get?
Bob . . .
Message 5
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| Subject: | Battery Load Testing |
=C2- The HF load tester is the quick'n dirty battery evaluator.
=C2- When you install a NEW battery. Make sure it's topped off
=C2- (Go flying for an hour).=C2- After landing, put the load tester
=C2- on, start the timer (15 seconds) and quickly crank the
=C2- knob up until the voltage FALLS to 9 volts. Adjust the
=C2- knob to maintain the 9v reading until the timer light
=C2- goes out. Then quickly observe and record the CURRENT
=C2- being delivered.
HF has a slightly different approach to this test.
Are there pros and cons of either method?
Roger
Message 6
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| Subject: | Re: Alternators - To Fuse or not to fuse - That |
IS the question
At 03:22 PM 9/9/2017, you wrote:
>Well, an single SLA has very different amp-hour
>ratings depending on the discharge rate. And
>'consumer' SLAs (PC680, etc that were originally
>intended for watercraft, and others that some of
>us use that were intended for UPSs and/or
>electric carts, etc) are rated differently from
>the certified a/c SLAs, if I've read spec sheets correctly.=C2
SVLA batteries have very significant internal
resistance which wastes energy under load . . .
a loss that increases with load. The battery's
USEFUL capacity must be tied to the load.
Here's the spread sheet on a PC680
Emacs!
Note that the LIGHTER you load it, the BETTER the
capacity. The PC680 is speced as a 16 a.h. device
at the 20 HOUR RATE.
But cranking your engine at 150 amps will get
your only 2 minutes of operation with a 65%
drop in capacity. The rest of that engergy will
be used up getting the battery hot.
Lithium's very low internal resistance produces
very flat load vs. capacity curves. Here's
an exemplar family of LiPo discharge curves.
Emacs!
Note that you get essentially ALL the capacity you
paid for irrespective of load.
Early on in the marketing of LiPo you saw the
term "lead acid equivalent". This was a smoke-n-
mirrors term created by the LiPo marketing that
spoke only to cranking ability . . . fine if
you owned a motor cycle or snowmobile. Totall
bogus for airplane guys that had ENDURANCE
requirements. I hammered EarthX about this and
in years since you will see BOTH numbers.
LAEQ and CAPAH.
I'll have to back off on that 10v figure for
using a load tester on LiPo batteries. The
Significant load test for LiPo has to be
select a number on a par with the real cranking
current of your engine. Apply THAT load for
15 seconds then read the voltage at the
end of 15 seconds.
The most telling figure of merit is still
ENDURANCE under anticipated load. Do that
in the hangar or get the instruments that
will count the electrons.
Bob . . .
Message 7
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| Subject: | Battery Load Testing |
>At 10:10 AM 9/10/2017, you wrote:
>
> The HF load tester is the quick'n dirty battery evaluator.
> When you install a NEW battery. Make sure it's topped off
> (Go flying for an hour). After landing, put the load tester
> on, start the timer (15 seconds) and quickly crank the
> knob up until the voltage FALLS to 9 volts. Adjust the
> knob to maintain the 9v reading until the timer light
> goes out. Then quickly observe and record the CURRENT
> being delivered.
>
> HF has a slightly different approach to this test.=C2
> Are there pros and cons of either method?
One could debate that for a long time. This
is comparative test . . . How much does
test #2 depart from test #1? Then test #3,
#4, etc.
Use any protocol that pushes the battery to
the edge of its performance capability and
keep track of results.
Bob . . .
Message 8
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| Subject: | Re: Manual intercom PTT |
That is clever, I'll try that. I've also been experimenting with using a tablespoon
measuring spoon as a wind shield. The two together might be a winner.
Jeff
Sent from my iPad
> On Sep 9, 2017, at 10:36 AM, Richard Girard <aslsa.rng@gmail.com> wrote:
>
> I made a mic cover from a battery terminal cover and some porous foam. Helped
with the wind noise in my trike.
>
> Rick Girard
>
>>
Message 9
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| Subject: | Re: Manual intercom PTT |
Jeff, early Extra 300s had an intercom system like you describe. The
throttle of both seats had a momentary push button to open the mike for
intercom and the stick had the radio PTT. That worked well for the pilot
but not so well for inexperienced pax who took a while to understand the
need to press the button on the throttle. Like Stein suggested I would
install a good I intercom first (and I would go with his recommendation, he
has some experience in this field...) before going down the intercom button
route. Peter
On 10 Sep 2017 3:34 p.m., "Jeff Point" <jpoint@wi.rr.com> wrote:
>
> That is clever, I'll try that. I've also been experimenting with using a
> tablespoon measuring spoon as a wind shield. The two together might be a
> winner.
>
> Jeff
>
> Sent from my iPad
>
> > On Sep 9, 2017, at 10:36 AM, Richard Girard <aslsa.rng@gmail.com> wrote:
> >
> > I made a mic cover from a battery terminal cover and some porous foam.
> Helped with the wind noise in my trike.
> >
> > Rick Girard
> >
> >>
>
>
Message 10
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| Subject: | Re: Manual intercom PTT |
Suggest contacting Sigtronics who designed an acceptable headset & intercom
for their T6. They also added a 'glove' over the mic with a very small
hole. It worked great in our Mustang II for years.
On Sun, Sep 10, 2017 at 7:01 PM, Peter Pengilly <peter@sportingaero.com>
wrote:
> Jeff, early Extra 300s had an intercom system like you describe. The
> throttle of both seats had a momentary push button to open the mike for
> intercom and the stick had the radio PTT. That worked well for the pilot
> but not so well for inexperienced pax who took a while to understand the
> need to press the button on the throttle. Like Stein suggested I would
> install a good I intercom first (and I would go with his recommendation, he
> has some experience in this field...) before going down the intercom button
> route. Peter
>
> On 10 Sep 2017 3:34 p.m., "Jeff Point" <jpoint@wi.rr.com> wrote:
>
>>
>> That is clever, I'll try that. I've also been experimenting with using a
>> tablespoon measuring spoon as a wind shield. The two together might be a
>> winner.
>>
>> Jeff
>>
>> Sent from my iPad
>>
>> > On Sep 9, 2017, at 10:36 AM, Richard Girard <aslsa.rng@gmail.com>
>> wrote:
>> >
>> > I made a mic cover from a battery terminal cover and some porous foam.
>> Helped with the wind noise in my trike.
>> >
>> > Rick Girard
>> >
>> >>
>>
>>
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