Today's Message Index:
----------------------
1. 04:04 AM - GRT-EIS Tach input (carlrai@aol.com)
2. 06:35 AM - Re: Cutting off battery posts (Eric M. Jones)
3. 06:42 AM - Re: Cutting off battery posts (paul wilson)
4. 06:44 AM - Re: Digital Ampmeter (Robert L. Nuckolls, III)
5. 09:25 AM - Re: Cutting off battery posts (Chuck Jensen)
6. 09:31 AM - Re: Cutting off battery posts (Terry Miles)
7. 09:34 AM - Re: Radios squawk ...literally (jerry2dt@aol.com)
8. 07:09 PM - Re: The importance of "good" numbers . . . (Eric M. Jones)
Message 1
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| Subject: | GRT-EIS Tach input |
Fellow Builders,
Currently close to completing wiring on an RV-9A.=C2- Among the last of th
e=C2- connections to complete are the tach input to the GR EIS.=C2-
I'm going to connect both mags to the input, using a switch to select L or R
input for RPM drop at runup.=C2-=C2-Two toggle switches are used for th
e L and R mag on/off.
Do I need to connect the tach=C2-input directly to the mags using a sepera
te shielded wire or can I simply use a double faston tab at the toggle switc
h to continue the mag wire to the EIS input?=C2- I assume if a continuatio
n is acceptable, it should also be shielded with the shield grounded at the
mag switch end - for noise only, not as part of the grounding circuit to shu
t down the mags.
Any and all suggestions are appreciated.
Carl Raichle
Lutz, FL
________________________________________________________________________
AOL at AOL.com.
Message 2
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| Subject: | Re: Cutting off battery posts |
The Optimal Battery one might use is the D51:
See http://tinyurl.com/2e3drf
The Optima website is abysmal and never improved or added to.
D51 is 26 pounds and 46 AH. The reason I like this battery is the claimed superior
resistance to vibration. My plan is to eschew the twin-battery and switchover
technique in favor of single-battery simplicity. If you wanted two batteries
these are probably too heavy.
But in my plan, there is an XBM Xantrex Battery Monitor that tells me everything
I need to know beforehand about the battery condition AND how many minutes of
battery life remains if the alternator quits. A second battery is another way
to do this job, but I think the reserve battery is not as good as total info
about the only battery.
I use a racecar battery connect-disconnect switch instead of a contactor. to satisfy
the FAA "one-hand disconnect" rule. The kill switch also cuts off the fuel
and perfoms other "pre-crash" functions.
Yes cutting off the terminals was a mistake. Perhaps Opitma can repair it for you.
Or perhaps "That's the price of an education".
---------
Every act of conscious learning requires the willingness to suffer an injury to
one's self-esteem. That is why young children, before they are aware of their
own self-importance, learn so easily.
--Thomas Szasz
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=120199#120199
Message 3
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| Subject: | Re: Cutting off battery posts |
Hi Terry,
I have 4 un,molested yellow tops (2 trucks with dual setups) and
one with very little use acts just like yours. I think the guy you
talked to is blowing smoke. The vent is independent with the battery
posts, unless you cut into the plastic case. By looking at the
battery it is obvious that there is a conductor path from top to side
posts. If you cut above the plastic surface the conduction path or
vent would not be affected. I think the design uses the top terminal
as the primary connection to the plates and the side post are just an
extension. Thus cutting the top post just above the plastic would
maintain the integrity of the battery. If you have voltage at the
side terminal after the cutting then you still have contact to the
plates and the battery should take a charge.
Bottom line, I think you just got a bad battery. You are not the only
one out there. The last time I bought yellow tops I had to wait for 3
weeks as their production was backed up. Just a sign of problems at
the factory. The quality had been going down hill since Johnson
bought the company.
I am having second thought about Optima.
Regards, Paul
============================
At 08:21 PM 6/22/2007, you wrote:
><terrence_miles@hotmail.com>
>
>Hi all,
>
>I bought a pair of Yellow Top Optima batteries. They are the absorbed gas
>matt type. They are located in the nose area and stacked one on top of the
>other in my Velocity XL. I cut the top posts off the bottom battery due to
>height limitations and planned to use the side posts.
>
>That turned out to be a mistake. Even though I have good continuity between
>the top post nub and the side posts, the battery will not accept an external
>charge. It shows 12.1 v or so, but collapses under any kind of load.
>Without being all that clear despite my best efforts to learn more of the
>mechanical connections involved...the tech service arm of Optima said
>cutting off the posts somehow compromises the top-post-to-side-post physical
>connection. He also said removing the posts opens the battery's controlled
>venting system to outside air.
>
>I was surprised at both of these discoveries...and out $200 to boot.
>
>Anybody out there running side post batteries w/ the top posts removed?
>
>Likely I am back to the drawing boards for a complete redesign now of
>battery size and hold downs, but I am considering one alternative and that
>is mounting a new Optima upside down with the top posts still in place by
>drilling holes in my mounting floor for the posts to protrude into. Risks
>there would be if I ever overcharged it, electrolyte would leak on the base
>surface. Any thoughts? Suggestions?
>
>Thanks
>Terry
>
>
Message 4
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| Subject: | Re: Digital Ampmeter |
At 10:42 PM 6/22/2007 +0100, you wrote:
><trigo@mail.telepac.pt>
>
>Bob
>
>Thanks for your quick and complete response.
>
>I have a couple of (electric instruments challenged guy) questions:
>
>If I use the first digital panel meter you suggested
>(http://www.mpja.com/download/12205me.pdf)
>do I simply connect power (9V and -) and the 2 wires from the shunt, and
>it will indicate Amps?
>
>The "Full scale range" of 200mV indicated in the specifications, has it
>anything to do with the 50mV characteristic of my shunt ?
>
>Carlos
Carlos, I'm not sure we've completely explained all the
toys and tools in the sandbox for achieving what you've
stated as a design goal:
See:
http://www.aeroelectric.com/Pictures/Schematics/DPM_Ammeter.jpg
This is a schematic for incorporating a low cost, digital
panel meter into an alternator loadmeter function using
a shunt. Note that while the low cost DPMs offer great
accuracy and value, they all have some limitations that make
it a challenge to install for your application. Note that
I show a separate 9v battery. These devices have a very limited
common mode range for the input signals. This means that we cannot
ground the power(-) lead for the DPM to power ground and supply
9V from ships power. The power supply has to "float" with
respect to the signal leads.
Using a battery to power this instrument is perhaps not as
bad an idea as you might think. The DPM draws very little
current and the battery will last for months. So if the
battery is easy to reach (velcro to some handy spot behind
panel) you can consider NOT having an on/off switch.
You'll want to have a 50A shunt . . . no matter what
size alternator you have so that the signal going to
the DPM is 1 millivolt per Amp. When you set the DPM
up to read in millivolts, then the display will
be calibrated to read out directly in amps. The
200 mV input to a 3-1/2 digit DPM has a max reading
of 199.9 mV so your instrument will read Amps of load
to the nearest 0.1 amps.
If you can accommodate the limitations of these inexpensive
but rather capable readout devices, they can offer some
dependable, accurate measurement at very reasonable
prices.
Bob . . .
Message 5
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| Subject: | Cutting off battery posts |
Hi, Terry,
I understand the dual battery setup and the reasons for it, but am still
not convinced the added complexity and weight is offset by the benefits.
I converted to the Odyssey PC925 with 980amp cranking. It's small,
lightweight, $130 and can be positioned any way except upside down. I
removed my original dual battery setup and went for simplicity. Even
with 14-15amp draw with everything turned on, I have more than enough
reserve to get to VFR is the alternator goes down. As far as cranking
power, the single PC925 has enough cranking power that the starter is
likely to melt before the juice is gone, so a second battery doesn't buy
me much except more weight, maintenance, electrical control complexity.
I've done both but would not go back to the two battery arrangement.
The single PC925 fits with lots of room to spare. Just a thought.
Chuck Jensen
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Terry
Miles
Sent: Friday, June 22, 2007 10:21 PM
Subject: AeroElectric-List: Cutting off battery posts
--> <terrence_miles@hotmail.com>
Hi all,
I bought a pair of Yellow Top Optima batteries. They are the absorbed
gas matt type. They are located in the nose area and stacked one on top
of the
other in my Velocity XL. I cut the top posts off the bottom battery
due to
height limitations and planned to use the side posts.
That turned out to be a mistake. Even though I have good continuity
between the top post nub and the side posts, the battery will not accept
an external charge. It shows 12.1 v or so, but collapses under any kind
of load. Without being all that clear despite my best efforts to learn
more of the mechanical connections involved...the tech service arm of
Optima said cutting off the posts somehow compromises the
top-post-to-side-post physical connection. He also said removing the
posts opens the battery's controlled venting system to outside air.
I was surprised at both of these discoveries...and out $200 to boot.
Anybody out there running side post batteries w/ the top posts removed?
Likely I am back to the drawing boards for a complete redesign now of
battery size and hold downs, but I am considering one alternative and
that is mounting a new Optima upside down with the top posts still in
place by drilling holes in my mounting floor for the posts to protrude
into. Risks there would be if I ever overcharged it, electrolyte would
leak on the base surface. Any thoughts? Suggestions?
Thanks
Terry
Message 6
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| Subject: | Cutting off battery posts |
Dear Bob, Paul and others,
Thanks for the thoughts and suggestions on my battery post issues. It's the
week-end now and I am not near the hangar to examine matters further. Since
Optima has refused any product warranty, it is all mine now, and so I will
carefully see if I can salvage the thing for shop use and let everyone know
what I discover. This was not my first faulted Yellow Top.
To answer your questions. The post turns out to actually be a lead ring
with a lead insert. The outer ring is about 3/16 inch thick. The lead
insert is clearly undersized maybe by 1/32 inch or so. It is not centered
within the outer ring nor does it appear to be precisely placed at all. (I
say this comparing one post to the other.) (I could have caused this by the
sawing activities--although they are not loose.)
The phone room Optima guy did try to blow smoke a little, but he was quick
to give me another phone number to engineering. The engineering fellow was
more helpful but still some shy on details. He was clear on the vent
issue--but I don't see any vents either, nor did I cut into the case.
They both said the vibration of the actual post sawing could have
compromised the top post/side post/battery chemisty connections.
Electrically there is no resistance from the outer ring to side posts, but
there was resistance when I measured the inner plugs to the side posts.
Bob, your battery link was correct. It is a "pig." I knew from reading
your book that I wanted the advantage of gel or of absorbed glass Mat (AGM)
technology. Mistakenly, I figured the more amps were always better and
saving wgt in the nose was not a factor for me. And I might add if it helps
anyone, I was perhaps over estimating my "in the chocks" ground delays
battery drain time prior to engine start up.
Thank you for helping. I will let everyone know if discover more about
Optima's structure in the week or so ahead. I still plan to stay with a
dual, matched-pair battery architecture. ...now maybe just more
appropriately sized. This was a good lesson learned and better so on the
ground.
Regards,
Terry
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Saturday, June 23, 2007 1:07 AM
Subject: Re: AeroElectric-List: Cutting off battery posts
<nuckollsr@cox.net>
At 10:21 PM 6/22/2007 -0400, you wrote:
><terrence_miles@hotmail.com>
>
>Hi all,
>
>I bought a pair of Yellow Top Optima batteries. They are the absorbed gas
>matt type. They are located in the nose area and stacked one on top of the
>other in my Velocity XL. I cut the top posts off the bottom battery due
to
>height limitations and planned to use the side posts.
>
>That turned out to be a mistake. Even though I have good continuity
between
>the top post nub and the side posts, the battery will not accept an
external
>charge. It shows 12.1 v or so, but collapses under any kind of load.
>Without being all that clear despite my best efforts to learn more of the
>mechanical connections involved...the tech service arm of Optima said
>cutting off the posts somehow compromises the top-post-to-side-post
physical
>connection. He also said removing the posts opens the battery's controlled
>venting system to outside air.
>
>I was surprised at both of these discoveries...and out $200 to boot.
>
>Anybody out there running side post batteries w/ the top posts removed?
Without knowing the details of how the post is molded and retained
in the battery housing, the experiment is not without risk . . . when
you cut the posts off, were they not solid? I.e., a smooth lead alloy
surface with no holes? I'm mystified as to how this would have
compromised
the seal if they were smooth, contiguous surfaces after cutting.
>Likely I am back to the drawing boards for a complete redesign now of
>battery size and hold downs, but I am considering one alternative and that
>is mounting a new Optima upside down with the top posts still in place by
>drilling holes in my mounting floor for the posts to protrude into. Risks
>there would be if I ever overcharged it, electrolyte would leak on the base
>surface. Any thoughts? Suggestions?
Those are real "pig" batteries. Do you NEED the capacity? Or the weight?
As I recall, the smallest of the yellow-top batteries are something on
the order of 50 a.h. batteries at a 2-hour rate and weighs about 44
pounds.
Is this the battery we're talking about?
http://tinyurl.com/2z8xgu
Unless you need the weight, surely there are smaller batteries that meet
your electrical needs that don't cost so much and will fit into the space
allotted?
Bob . . .
Message 7
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| Subject: | Re: Radios squawk ...literally |
Thanks Wayne,
Already tried that, no joy. Currently on a trip, so will pursue the matter when
I get back to the hangar.
However, problem went away when copilot headset (brand new) is unplugged. Then
both COMMS work fine, transmit and receive...
Jerry Cochran
Time: 08:25:43 AM PST US
From: W Meier <befliegen@msn.com>
Subject: Re: AeroElectric-List: Radios squawk ...literally
Try turning one of the transmitters off. If both are transmitting at
the same time (not by design, but for some unknown reason), the
frequencies "beat" against each other and the resultant squeal is the
difference between them.
Wayne
Jerry2DT@aol.com wrote:
> Folks,
>
> Away from home with very annoying problem... Dual Icom's, dual
> antennas,same problem either one. Hit transmit and I send out a squeal
> with voice. other pilots say it is LOUD!! Before I borrow tools and
> tear things apart, any suggestions? Only one PTT switch wired in at
> present. Sound like a bad ground somewheres?
>
> Any and all help very appreciated.
>
> Jerry Cochran
-----Original Message-----
From: AeroElectric-List Digest Server <aeroelectric-list@matronics.com>
Sent: Fri, 22 Jun 2007 11:55 pm
Subject: AeroElectric-List Digest: 12 Msgs - 06/22/07
*
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AeroElectric-List Digest Archive
---
Total Messages Posted Fri 06/22/07: 12
----------------------------------------------------------
Today's Message Index:
----------------------
1. 04:25 AM - Internal reg failed. Everything fried (Bob Barrow)
2. 06:28 AM - Re: Question about Aux battery contactor on Z30 (Robert L.
Nuckolls, III)
3. 06:51 AM - Re: Internal reg failed. Everything fried (Robert L.
Nuckolls, III)
4. 08:25 AM - Re: Radios squawk ...literally (W Meier)
5. 08:56 AM - Digital Ampmeter (Carlos Trigo)
6. 01:08 PM - Re: Digital Ampmeter (Robert L. Nuckolls, III)
7. 01:26 PM - Digital Ampmeter (P.S.) (Robert L. Nuckolls, III)
8. 02:47 PM - Re: Digital Ampmeter (Carlos Trigo)
9. 07:23 PM - Cutting off battery posts (Terry Miles)
10. 07:40 PM - Re: Digital Ampmeter (Richard E. Tasker)
11. 07:46 PM - Re: Digital Ampmeter (Robert L. Nuckolls, III)
12. 09:08 PM - Re: Cutting off battery posts (Robert L. Nuckolls, III)
________________________________ Message 1 _____________________________________
Time: 04:25:24 AM PST US
From: "Bob Barrow" <bobbarrow10@hotmail.com>
Subject: AeroElectric-List: Internal reg failed. Everything fried
The following copy of a post on the Yahoo GRT_EFIS group site is most
interesting. It seems the internal regulator on a Vans supplied alternator
failed on an RV and the resultant overvoltage fried all of the avionics.
FOR THE WHAT ITS WORTH COLUMN. WE HAVE HAD THE GRT EFIS AND EIS
INSTALLED IN AN RV9A AND HAVE NOTHING BUT GOOD THINGS TO SAY ABOUT
THE COMPANY, THE PEOPLE AND THE EQUIPMENT.
WE HAD OVER 300 HRS ON THE GRT EQUIP AND WE WERE FLYING FROM TYLER
TEXAS TO VICKSBURG MISSISSIPPI WHEN OUR ALT (FROM VANS FIREWALL
FORWARD PACKAGE) TOSSED ITS INTERNAL VOLTAGE REGULATOR INTO THE
ARMATURE. THE RESULT WAS THAT EVERTYING FRIED.
AS YOU ALL PROBABLY KNOW , AN OVERVOLTAGE IS NOT PROTECTED BY
BREAKERS. OUR SL30, 327 AUTO PILOTS AND .....EVERYTHING FRIED.
WE SENT OUR COOKED EFIS, AND EIS TO GRT AND TOLD THEM THAT IT WAS
NOT THEIR EQUIPMENT THAT FAILED BUT RATHER THE ABOVE,,,, THEIR
RESPONSE.... THEY SENT US NEW ONES ? IT IS RARE TO FIND A COMPANY
WITH THAT MUCH EXPERTISE AND ... HOW DO YOU DESCRIBE THAT KIND OF
SERVICE? GOOD WILL?
FRED HOLLOWAY
_________________________________________________________________
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________________________________ Message 2 _____________________________________
Time: 06:28:27 AM PST US
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: RE: AeroElectric-List: Question about Aux battery contactor on Z30
At 08:50 PM 6/21/2007 -0600, you wrote:
>Bob,
>
>Thank you for the quick response and the multiply options. In building an
>airplane, so far, the electrical is by far the most intriguing to me.
>Thanks again,
I'm pleased that you find value in the
$time$ you spend here . . .
Bob . . .
________________________________ Message 3 _____________________________________
Time: 06:51:43 AM PST US
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: Internal reg failed. Everything fried
. . . any student of the assemblage of simple-ideas that
form a useful invention ultimately comes to understand
that the risk for such events is never zero . . . and the
$time$ to achieve 1x10^-6 reliability is great.
So, the cost effective approach hangs a hat on a parallel
concept . . . failure tolerance.
Assuming we know nothing about the pedigree of the simple-
ideas and cooks that crafted any particular alternator, the
prudent system designer simply assumes that the alternator can
and will fail in ugly ways at some point in time.
The traditional approach to making that failure tolerable
is to (1) fit the system with a means by which the pilot
exercises absolute control, (2) fit the system with active
notification of malfunction and (3) install an automatic,
milliseconds fast responder to the OV event that exercises
feature (1) which causes feature (2) to announce that the
alternator is off line . . . for whatever reason.
In terms of SYSTEM reliability, one can easily deduce that
the likelihood of a failure in the alternator and in either
(1), (2) or (3) happening together on the same tank full of
fuel is exceedingly small. Now if one has a well considered
plan-b for the unexpected alternator shut-down event, then
the builder has crafted great SYSTEM reliability from
a collection of components for which there is little or no
data as to the reliability of any one component.
The anecdote cited has no "hard evidence" by virtue of
an autopsy of the alleged failure but the byproducts of
that failure are inarguable and the source of the energy
that caused the damage is not debatable. This is an expensive
lesson that has taxed the $time$ of someone else . . . who has
seen fit to make us beneficiaries of his/her experience
and observations.
It would be foolish of us not to exploit that information
and apply the best-we-know-how-to-do as a prophylactic against
sharing the writer's experience. This ladies and gentlemen
is not a dark-n-stormy-night story that yields little
data for refining a recipe for success. It's a bright-light-
of-day-illumination of how a particular recipe failed
in expensive ways but fortunately without injury to the
"cooks".
Thank you Mr. Barrow for sharing this with us.
Bob . . .
At 09:23 PM 6/22/2007 +1000, you wrote:
><bobbarrow10@hotmail.com>
>
>The following copy of a post on the Yahoo GRT_EFIS group site is most
>interesting. It seems the internal regulator on a Vans supplied alternator
>failed on an RV and the resultant overvoltage fried all of the avionics.
>
>FOR THE WHAT ITS WORTH COLUMN. WE HAVE HAD THE GRT EFIS AND EIS
>INSTALLED IN AN RV9A AND HAVE NOTHING BUT GOOD THINGS TO SAY ABOUT
>THE COMPANY, THE PEOPLE AND THE EQUIPMENT.
>
>WE HAD OVER 300 HRS ON THE GRT EQUIP AND WE WERE FLYING FROM TYLER
>TEXAS TO VICKSBURG MISSISSIPPI WHEN OUR ALT (FROM VANS FIREWALL
>FORWARD PACKAGE) TOSSED ITS INTERNAL VOLTAGE REGULATOR INTO THE
>ARMATURE. THE RESULT WAS THAT EVERTYING FRIED.
>
>AS YOU ALL PROBABLY KNOW , AN OVERVOLTAGE IS NOT PROTECTED BY
>BREAKERS. OUR SL30, 327 AUTO PILOTS AND .....EVERYTHING FRIED.
>
>WE SENT OUR COOKED EFIS, AND EIS TO GRT AND TOLD THEM THAT IT WAS
>NOT THEIR EQUIPMENT THAT FAILED BUT RATHER THE ABOVE,,,, THEIR
>RESPONSE.... THEY SENT US NEW ONES ? IT IS RARE TO FIND A COMPANY
>WITH THAT MUCH EXPERTISE AND ... HOW DO YOU DESCRIBE THAT KIND OF
>SERVICE? GOOD WILL?
>
>FRED HOLLOWAY
________________________________ Message 4 _____________________________________
Time: 08:25:43 AM PST US
From: W Meier <befliegen@msn.com>
Subject: Re: AeroElectric-List: Radios squawk ...literally
Try turning one of the transmitters off. If both are transmitting at
the same time (not by design, but for some unknown reason), the
frequencies "beat" against each other and the resultant squeal is the
difference between them.
Wayne
Jerry2DT@aol.com wrote:
> Folks,
>
> Away from home with very annoying problem... Dual Icom's, dual
> antennas,same problem either one. Hit transmit and I send out a squeal
> with voice. other pilots say it is LOUD!! Before I borrow tools and
> tear things apart, any suggestions? Only one PTT switch wired in at
> present. Sound like a bad ground somewheres?
>
> Any and all help very appreciated.
>
> Jerry Cochran
>
>
> ------------------------------------------------------------------------
> See what's free at AOL.com
> <http://www.aol.com?ncid=AOLAOF00020000000503>.
> *
>
>
> *
________________________________ Message 5 _____________________________________
Time: 08:56:21 AM PST US
From: "Carlos Trigo" <trigo@mail.telepac.pt>
Subject: AeroElectric-List: Digital Ampmeter
I installed a 50 mV shunt in the AWG 6 wire coming from the alternator, to
measure Amps "produced" by it, and I don't want to put an analog Ampmeter in
my pannel.
Can someone please indicate me a source and a model of digital ampmeter to
connect to my shunt.
TIA
Carlos
________________________________ Message 6 _____________________________________
Time: 01:08:04 PM PST US
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: Digital Ampmeter
At 04:48 PM 6/22/2007 +0100, you wrote:
><trigo@mail.telepac.pt>
>
>I installed a 50 mV shunt in the AWG 6 wire coming from the alternator, to
>measure Amps "produced" by it, and I don't want to put an analog Ampmeter
>in my pannel.
>Can someone please indicate me a source and a model of digital ampmeter to
>connect to my shunt.
>
>TIA
>Carlos
It's not a simple answer. Unlike the ordinary analog instrument,
a digital instrument cares about how much voltage is on the shunt
with respect to ground. The instrument is trying to deduce and display
a voltage on the order of millivolts while shunt is riding above ground
by about 14,000 millivolts and has a lot of 'noise' on it. The ability
to ignore the big picture while staying accurately focused on the little
picture is not a trivial task.
Most manufacturers get around it by using the hall effect sensor
which doesn't care how much voltage is on the sensed wire . . . it
cares only about the magnetic field around the wire that results
from the flow of the current to be measured.
If you're dead set against an analog (pretty cheap at $50) like
https://matronics.com/aeroelectric/Catalog/AEC/9007/9007.html
then in order to use a digital instrument, you'll need to
find one that can either run from your 14v bus and resolve
a millivolt signal riding on 14v common mode or select an
LCD instrument that runs from a 9v battery (just leave it on
all the time. Battery lasts for months!) and doesn't worry
about the 14v common mode thing. An example of the later
instrument can be seen at:
http://www.mpja.com/download/12205me.pdf
These are inexpensive but you'll note that the input
signal must lie within plus or minus 1.0 volts of
the instrument's ground (Com Mode Voltage).
Now, there ARE ways that one can craft a shunt signal
processing amplifier using a device with a very high
common mode capability. And example of such a part is
the Analog Devices AD628
http://www.analog.com/UploadedFiles/Data_Sheets/AD628.pdf
Note that this puppy is designed to live in a very
large common mode range of over plus/minus 100 volts.
This is the type of device employed by folks to choose to
offer digital displays driven by shunts. However, most
digital suppliers no probably use hall-sensors and step
over the common mode limits.
I thought JPI or Electronics International had stand
alone ammeters and voltmeters but a quick check of their
websites didn't turn anything up. Perhaps someone else on
the list will have some suggestions. It seems the trends
are toward multifunction instrument packages that include
volts and amps. Stand alone instruments are going to be
increasingly difficult to find.
The easiest thing to do is bite the bullet and
go the stone-simple analog instrument. You can spend
a lot of time and a lot more money getting to the
digital solution.
Bob . . .
________________________________ Message 7 _____________________________________
Time: 01:26:34 PM PST US
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: AeroElectric-List: Digital Ampmeter (P.S.)
At 03:05 PM 6/22/2007 -0600, you wrote:
<nuckollsr@cox.net>
At 04:48 PM 6/22/2007 +0100, you wrote:
I installed a 50 mV shunt in the AWG 6 wire coming from the
alternator, to measure Amps "produced" by it, and I don't want
to put an analog Ampmeter in my pannel. Can someone please indicate
me a source and a model of digital ampmeter to connect to my shunt.
TIA
Carlos
It's not a simple answer. Unlike the ordinary analog instrument,
a digital instrument cares about how much voltage is on the shunt
with respect to ground. The instrument is trying to deduce and display
a voltage on the order of millivolts while shunt is riding above ground
by about 14,000 millivolts and has a lot of 'noise' on it. The ability
to ignore the big picture while staying accurately focused on the little
picture is not a trivial task.
Most manufacturers get around it by using the hall effect sensor
which doesn't care how much voltage is on the sensed wire . . . it
cares only about the magnetic field around the wire that results
from the flow of the current to be measured.
If you're dead set against an analog (pretty cheap at $50) like
https://matronics.com/aeroelectric/Catalog/AEC/9007/9007.html
then in order to use a digital instrument, you'll need to
find one that can either run from your 14v bus and resolve
a millivolt signal riding on 14v common mode or select an
LCD instrument that runs from a 9v battery (just leave it on
all the time. Battery lasts for months!) and doesn't worry
about the 14v common mode thing. An example of the later
instrument can be seen at:
http://www.mpja.com/download/12205me.pdf
These are inexpensive but you'll note that the input
signal must lie within plus or minus 1.0 volts of
the instrument's ground (Com Mode Voltage).
Now, there ARE ways that one can craft a shunt signal
processing amplifier using a device with a very high
common mode capability. And example of such a part is
the Analog Devices AD628
http://www.analog.com/UploadedFiles/Data_Sheets/AD628.pdf
Note that this puppy is designed to live in a very
large common mode range of over plus/minus 100 volts.
This is the type of device employed by folks to choose to
offer digital displays driven by shunts. However, most
digital suppliers no probably use hall-sensors and step
over the common mode limits.
I thought JPI or Electronics International had stand
alone ammeters and voltmeters but a quick check of their
websites didn't turn anything up. Perhaps someone else on
the list will have some suggestions. It seems the trends
are toward multifunction instrument packages that include
volts and amps. Stand alone instruments are going to be
increasingly difficult to find.
The easiest thing to do is bite the bullet and
go the stone-simple analog instrument. You can spend
a lot of time and a lot more money getting to the
digital solution.
P.S.
If you wanted to shed the shunt and roll your own hall-effect
loadmeter, consider the parts from AmpLoc at:
http://amploc.com/PRO%20Series.pdf
You could combine one of these sensors with an inexpensive
DPM . . .
http://mpja.com/productview.asp?product=16179+ME
. . . and probably craft a loadmeter for under $40 in materials
and take care of the common mode problem at the same time.
Bob . . .
________________________________ Message 8 _____________________________________
Time: 02:47:46 PM PST US
From: "Carlos Trigo" <trigo@mail.telepac.pt>
Subject: Re: AeroElectric-List: Digital Ampmeter
Bob
Thanks for your quick and complete response.
I have a couple of (electric instruments challenged guy) questions:
If I use the first digital panel meter you suggested
(http://www.mpja.com/download/12205me.pdf)
do I simply connect power (9V and -) and the 2 wires from the shunt, and it
will indicate Amps?
The "Full scale range" of 200mV indicated in the specifications, has it
anything to do with the 50mV characteristic of my shunt ?
Carlos
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Sent: Friday, June 22, 2007 10:26 PM
Subject: AeroElectric-List: Digital Ampmeter (P.S.)
> <nuckollsr@cox.net>
>
> At 03:05 PM 6/22/2007 -0600, you wrote:
>
> <nuckollsr@cox.net>
>
> At 04:48 PM 6/22/2007 +0100, you wrote:
>
> <trigo@mail.telepac.pt>
>
> I installed a 50 mV shunt in the AWG 6 wire coming from the
> alternator, to measure Amps "produced" by it, and I don't want
> to put an analog Ampmeter in my pannel. Can someone please indicate
> me a source and a model of digital ampmeter to connect to my shunt.
>
> TIA
> Carlos
>
> It's not a simple answer. Unlike the ordinary analog instrument,
> a digital instrument cares about how much voltage is on the shunt
> with respect to ground. The instrument is trying to deduce and display
> a voltage on the order of millivolts while shunt is riding above ground
> by about 14,000 millivolts and has a lot of 'noise' on it. The ability
> to ignore the big picture while staying accurately focused on the little
> picture is not a trivial task.
>
> Most manufacturers get around it by using the hall effect sensor
> which doesn't care how much voltage is on the sensed wire . . . it
> cares only about the magnetic field around the wire that results
> from the flow of the current to be measured.
>
> If you're dead set against an analog (pretty cheap at $50) like
>
> https://matronics.com/aeroelectric/Catalog/AEC/9007/9007.html
>
> then in order to use a digital instrument, you'll need to
> find one that can either run from your 14v bus and resolve
> a millivolt signal riding on 14v common mode or select an
> LCD instrument that runs from a 9v battery (just leave it on
> all the time. Battery lasts for months!) and doesn't worry
> about the 14v common mode thing. An example of the later
> instrument can be seen at:
>
> http://www.mpja.com/download/12205me.pdf
>
> These are inexpensive but you'll note that the input
> signal must lie within plus or minus 1.0 volts of
> the instrument's ground (Com Mode Voltage).
>
> Now, there ARE ways that one can craft a shunt signal
> processing amplifier using a device with a very high
> common mode capability. And example of such a part is
> the Analog Devices AD628
>
> http://www.analog.com/UploadedFiles/Data_Sheets/AD628.pdf
>
> Note that this puppy is designed to live in a very
> large common mode range of over plus/minus 100 volts.
> This is the type of device employed by folks to choose to
> offer digital displays driven by shunts. However, most
> digital suppliers no probably use hall-sensors and step
> over the common mode limits.
>
> I thought JPI or Electronics International had stand
> alone ammeters and voltmeters but a quick check of their
> websites didn't turn anything up. Perhaps someone else on
> the list will have some suggestions. It seems the trends
> are toward multifunction instrument packages that include
> volts and amps. Stand alone instruments are going to be
> increasingly difficult to find.
>
> The easiest thing to do is bite the bullet and
> go the stone-simple analog instrument. You can spend
> a lot of time and a lot more money getting to the
> digital solution.
>
> P.S.
>
> If you wanted to shed the shunt and roll your own hall-effect
> loadmeter, consider the parts from AmpLoc at:
>
> http://amploc.com/PRO%20Series.pdf
>
> You could combine one of these sensors with an inexpensive
> DPM . . .
>
> http://mpja.com/productview.asp?product=16179+ME
>
> . . . and probably craft a loadmeter for under $40 in materials
> and take care of the common mode problem at the same time.
>
>
> Bob . . .
>
>
>
________________________________ Message 9 _____________________________________
Time: 07:23:21 PM PST US
From: "Terry Miles" <terrence_miles@hotmail.com>
Subject: AeroElectric-List: Cutting off battery posts
Hi all,
I bought a pair of Yellow Top Optima batteries. They are the absorbed gas
matt type. They are located in the nose area and stacked one on top of the
other in my Velocity XL. I cut the top posts off the bottom battery due to
height limitations and planned to use the side posts.
That turned out to be a mistake. Even though I have good continuity between
the top post nub and the side posts, the battery will not accept an external
charge. It shows 12.1 v or so, but collapses under any kind of load.
Without being all that clear despite my best efforts to learn more of the
mechanical connections involved...the tech service arm of Optima said
cutting off the posts somehow compromises the top-post-to-side-post physical
connection. He also said removing the posts opens the battery's controlled
venting system to outside air.
I was surprised at both of these discoveries...and out $200 to boot.
Anybody out there running side post batteries w/ the top posts removed?
Likely I am back to the drawing boards for a complete redesign now of
battery size and hold downs, but I am considering one alternative and that
is mounting a new Optima upside down with the top posts still in place by
drilling holes in my mounting floor for the posts to protrude into. Risks
there would be if I ever overcharged it, electrolyte would leak on the base
surface. Any thoughts? Suggestions?
Thanks
Terry
________________________________ Message 10 ____________________________________
Time: 07:40:54 PM PST US
From: "Richard E. Tasker" <retasker@optonline.net>
Subject: Re: AeroElectric-List: Digital Ampmeter
Since Bob has not answered yet, I will. The 50mV shunt will drop 50mV
at it's rated amperage. You didn't specify what one you have, but let's
assume that it is a 50mV shunt at 50 Amps. The voltage drop across the
shunt will vary from 0V to 50 mV as the current goes from 0A to 50 A.
The digital voltmeter has a 200 mV full scale readout so it will read 0
to 50 mV. If you indeed have the shunt in the example above, then the
meter will read 0-50mV which you can interpret to be 0-50A.
If you have some other range shunt, the you will have to interpret the
reading. For example, if you have a 100 A shunt then it will have a 50
mV drop at 100 amps and the digital meter will read 50 mV when you have
100 amps flowing.
Dick Tasker
Carlos Trigo wrote:
> <trigo@mail.telepac.pt>
>
> Bob
>
> Thanks for your quick and complete response.
>
> I have a couple of (electric instruments challenged guy) questions:
>
> If I use the first digital panel meter you suggested
> (http://www.mpja.com/download/12205me.pdf)
> do I simply connect power (9V and -) and the 2 wires from the shunt,
> and it will indicate Amps?
>
> The "Full scale range" of 200mV indicated in the specifications, has
> it anything to do with the 50mV characteristic of my shunt ?
>
> Carlos
>
>
> ----- Original Message ----- From: "Robert L. Nuckolls, III"
> <nuckollsr@cox.net>
> To: <aeroelectric-list@matronics.com>
> Sent: Friday, June 22, 2007 10:26 PM
> Subject: AeroElectric-List: Digital Ampmeter (P.S.)
>
>
>> <nuckollsr@cox.net>
>>
>> At 03:05 PM 6/22/2007 -0600, you wrote:
>>
>> <nuckollsr@cox.net>
>>
>> At 04:48 PM 6/22/2007 +0100, you wrote:
>>
>> <trigo@mail.telepac.pt>
>>
>> I installed a 50 mV shunt in the AWG 6 wire coming from the
>> alternator, to measure Amps "produced" by it, and I don't want
>> to put an analog Ampmeter in my pannel. Can someone please indicate
>> me a source and a model of digital ampmeter to connect to my shunt.
>>
>> TIA
>> Carlos
>>
>> It's not a simple answer. Unlike the ordinary analog instrument,
>> a digital instrument cares about how much voltage is on the shunt
>> with respect to ground. The instrument is trying to deduce and display
>> a voltage on the order of millivolts while shunt is riding above
>> ground
>> by about 14,000 millivolts and has a lot of 'noise' on it. The ability
>> to ignore the big picture while staying accurately focused on the
>> little
>> picture is not a trivial task.
>>
>> Most manufacturers get around it by using the hall effect sensor
>> which doesn't care how much voltage is on the sensed wire . . . it
>> cares only about the magnetic field around the wire that results
>> from the flow of the current to be measured.
>>
>> If you're dead set against an analog (pretty cheap at $50) like
>>
>> https://matronics.com/aeroelectric/Catalog/AEC/9007/9007.html
>>
>> then in order to use a digital instrument, you'll need to
>> find one that can either run from your 14v bus and resolve
>> a millivolt signal riding on 14v common mode or select an
>> LCD instrument that runs from a 9v battery (just leave it on
>> all the time. Battery lasts for months!) and doesn't worry
>> about the 14v common mode thing. An example of the later
>> instrument can be seen at:
>>
>> http://www.mpja.com/download/12205me.pdf
>>
>> These are inexpensive but you'll note that the input
>> signal must lie within plus or minus 1.0 volts of
>> the instrument's ground (Com Mode Voltage).
>>
>> Now, there ARE ways that one can craft a shunt signal
>> processing amplifier using a device with a very high
>> common mode capability. And example of such a part is
>> the Analog Devices AD628
>>
>> http://www.analog.com/UploadedFiles/Data_Sheets/AD628.pdf
>>
>> Note that this puppy is designed to live in a very
>> large common mode range of over plus/minus 100 volts.
>> This is the type of device employed by folks to choose to
>> offer digital displays driven by shunts. However, most
>> digital suppliers no probably use hall-sensors and step
>> over the common mode limits.
>>
>> I thought JPI or Electronics International had stand
>> alone ammeters and voltmeters but a quick check of their
>> websites didn't turn anything up. Perhaps someone else on
>> the list will have some suggestions. It seems the trends
>> are toward multifunction instrument packages that include
>> volts and amps. Stand alone instruments are going to be
>> increasingly difficult to find.
>>
>> The easiest thing to do is bite the bullet and
>> go the stone-simple analog instrument. You can spend
>> a lot of time and a lot more money getting to the
>> digital solution.
>>
>> P.S.
>>
>> If you wanted to shed the shunt and roll your own hall-effect
>> loadmeter, consider the parts from AmpLoc at:
>>
>> http://amploc.com/PRO%20Series.pdf
>>
>> You could combine one of these sensors with an inexpensive
>> DPM . . .
>>
>> http://mpja.com/productview.asp?product=16179+ME
>>
>> . . . and probably craft a loadmeter for under $40 in materials
>> and take care of the common mode problem at the same time.
>>
>>
>>
>> Bob . . .
>>
>>
>>
>>
>>
>>
>>
>
>
--
Please Note:
No trees were destroyed in the sending of this message. We do concede, however,
that a significant number of electrons may have been temporarily inconvenienced.
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________________________________ Message 11 ____________________________________
Time: 07:46:48 PM PST US
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: Digital Ampmeter
At 10:42 PM 6/22/2007 +0100, you wrote:
><trigo@mail.telepac.pt>
>
>Bob
>
>Thanks for your quick and complete response.
>
>I have a couple of (electric instruments challenged guy) questions:
>
>If I use the first digital panel meter you suggested
>(http://www.mpja.com/download/12205me.pdf)
>do I simply connect power (9V and -) and the 2 wires from the shunt, and
>it will indicate Amps?
>
>The "Full scale range" of 200mV indicated in the specifications, has it
>anything to do with the 50mV characteristic of my shunt ?
No, the instrument cited doesn't have sufficient common mode range to
use with your shunt. You would either have to convert from a shunt to
a hall-effect sensor . . .
-OR- build the signal conditioning amplifier I suggested using the
AD628 chip
-OR- you could use a 9v battery to power the instrument, leave it
hooked up all the time (but easy to replace) and set the instrument
to read 200.0 Mv full-scale. Now, if your shunt is a 50A shunt
(50 mv = 50A) then the instrument will now read correctly in amps
to the nearest 0.1 amps.
Bob . . .
________________________________ Message 12 ____________________________________
Time: 09:08:05 PM PST US
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Subject: Re: AeroElectric-List: Cutting off battery posts
At 10:21 PM 6/22/2007 -0400, you wrote:
><terrence_miles@hotmail.com>
>
>Hi all,
>
>I bought a pair of Yellow Top Optima batteries. They are the absorbed gas
>matt type. They are located in the nose area and stacked one on top of the
>other in my Velocity XL. I cut the top posts off the bottom battery due to
>height limitations and planned to use the side posts.
>
>That turned out to be a mistake. Even though I have good continuity between
>the top post nub and the side posts, the battery will not accept an external
>charge. It shows 12.1 v or so, but collapses under any kind of load.
>Without being all that clear despite my best efforts to learn more of the
>mechanical connections involved...the tech service arm of Optima said
>cutting off the posts somehow compromises the top-post-to-side-post physical
>connection. He also said removing the posts opens the battery's controlled
>venting system to outside air.
>
>I was surprised at both of these discoveries...and out $200 to boot.
>
>Anybody out there running side post batteries w/ the top posts removed?
Without knowing the details of how the post is molded and retained
in the battery housing, the experiment is not without risk . . . when
you cut the posts off, were they not solid? I.e., a smooth lead alloy
surface with no holes? I'm mystified as to how this would have compromised
the seal if they were smooth, contiguous surfaces after cutting.
>Likely I am back to the drawing boards for a complete redesign now of
>battery size and hold downs, but I am considering one alternative and that
>is mounting a new Optima upside down with the top posts still in place by
>drilling holes in my mounting floor for the posts to protrude into. Risks
>there would be if I ever overcharged it, electrolyte would leak on the base
>surface. Any thoughts? Suggestions?
Those are real "pig" batteries. Do you NEED the capacity? Or the weight?
As I recall, the smallest of the yellow-top batteries are something on
the order of 50 a.h. batteries at a 2-hour rate and weighs about 44 pounds.
Is this the battery we're talking about?
http://tinyurl.com/2z8xgu
Unless you need the weight, surely there are smaller batteries that meet
your electrical needs that don't cost so much and will fit into the space
allotted?
Bob . . .
________________________________________________________________________
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| Subject: | Re: The importance of "good" numbers . . . |
Nice info Bob. Temperature measuments are hard to do. I think this problem has
kept cold fusion guys going for over a decade. I frankly worry about global warming
that has been accelerating for the past six years... on Mars. There are
some "hand-waving" explanations for this, but you gotta' wonder....
> (From USA Today: The USA's highest temperature, 134 on July 10, 1913 in Death
Valley, Calif., is also the official highest temperature in the Western Hemisphere.
>
> The world's highest official temperature is 136 recorded at El Azizia, Libya,
on Sept. 13, 1922.
>
> Not everyone agrees that the Death Valley and El Azizia records are valid. Some
meteorologists say that a sandstorm was going on at the time 134 was measured
at Greenland Ranch in Death Valley and that very hot sand and dust could have
hit the thermometer inside its shelter, pushing its measurement higher than
the actual temperature of the air.
Now the TRUE story (well...legend has it), is that the guy at Furnace Creek July
10, 1913, didn't go out to Badwater, where the official thermometer coop was
a 1/2 mile out on the salt flat. He merely estimated the temperature at the -282
elevation by knowing that it ran some few degrees hotter than the temperature
at Furnace Creek. So the record USA high temperature is unofficial in the
strictest sense. If you go to Furnace Creek in mid-July you will know this is
probably true.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=120280#120280
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