Today's Message Index:
----------------------
1. 06:33 AM - Re: Simple electrical System for wooden biplane VFR (racerjerry)
2. 07:06 AM - Re: Re-juvinate a NiCad Battery? (Robert L. Nuckolls, III)
3. 07:39 AM - Re: Re-juvinate a NiCad Battery? (rayj)
4. 08:27 AM - Re: Re-juvinate a NiCad Battery? (Noel Loveys)
5. 08:27 AM - Re: Coolie Hat Switch (David)
6. 08:28 AM - Re-juvinate a NiCad Battery? (Charles Brame)
7. 08:52 AM - Re: battery chargers (David)
8. 08:53 AM - Re: Re-juvinate a NiCad Battery? (David)
9. 12:35 PM - Re: Fw: Re: Fw: Coolie Hat Switch (Robert L. Nuckolls, III)
10. 12:36 PM - Re: Re-juvinate a NiCad Battery? (Robert L. Nuckolls, III)
11. 12:58 PM - Re: Fw: Re: Fw: Coolie Hat Switch ()
12. 12:58 PM - BNC Shells touching (rvg8tor)
13. 01:09 PM - Re: Re-juvinate a NiCad Battery? (Robert L. Nuckolls, III)
14. 01:16 PM - Re: Re-juvinate a NiCad Battery? (Robert L. Nuckolls, III)
15. 01:31 PM - Re: Re-juvinate a NiCad Battery? (rayj)
16. 02:28 PM - Re: Re-juvinate a NiCad Battery? (David)
17. 03:00 PM - Re: BNC Shells touching (Robert L. Nuckolls, III)
18. 03:31 PM - Re: Re: Lamar DSX1240-1 Alternator (Robert L. Nuckolls, III)
19. 10:47 PM - Re: Re-juvinate a NiCad Battery? (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Simple electrical System for wooden biplane VFR |
I am unfamiliar with your magneto. Check to see if your magneto P leads are shielded.
Typically, the P leads are made from 16 gauge shielded wire. Look at
the magneto end of the wire and you should see the shielding separated out and
terminated into a separate ground connection at the magneto housing.
Due to vibration, it is fairly common to see this ground connection break and open
up. Since you say the interference problem only recently began, I suspect
that this is what has occurred.
--------
Jerry King
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=367976#367976
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| Subject: | Re: Re-juvinate a NiCad Battery? |
At 03:20 PM 3/7/2012, you wrote:
In an earlier post you mentioned that the life of rechargeable
batteries could be extended by operating them in a 40% to 70%
range. My question is how is the percent of charge state quantified?
It it isn't . . . not without measurements. Many battery
powered devices, especially laptops have smart batteries
fitted with circuitry that measures the energy
required to top off a battery and compares it with the
energy demands of the computer. As the battery ages,
the predicted endurance for the battery goes down even
though the percentage of available capacity gets topped
off to 100% each cycle.
The better rule of thumb for both NiCd and HiMh
technologies is to use them. They seem to enjoy being
cycled. Unlike the LiIon battery that is damaged by deep
discharge below 10% or so, you don't hurt the metal
batteries by taking them all the way to zero. You don't
want to store them in a discharged state . . . which
suggests some form of maintainer tray to keep service-
ready cells topped off for regular use.
It's almost a certainty that I would have enjoyed much
longer service lives from metal cells I've owned if
I had invested time and equipment to their maintenance.
At some point the economics fall apart when you spend
many times more $value$ in maximizing the service
life than the battery costs to simply replace it.
Bob . . .
Message 3
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| Subject: | Re: Re-juvinate a NiCad Battery? |
Is it voltage that is measured. Does the manufacturer supply a voltage
vs. % charge graph or table? Or is it derived experimentally?
I understand that there are cost/benefit issues here, but my objective
is to understand the process from a physics perspective for my own
education.
Thanks again for taking the time to help.
Raymond Julian
Kettle River, MN
"And you know that I could have me a million more friends,
and all I'd have to lose is my point of view." - John Prine
On 03/08/2012 09:04 AM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 03:20 PM 3/7/2012, you wrote:
>
> In an earlier post you mentioned that the life of rechargeable batteries
> could be extended by operating them in a 40% to 70% range. My question
> is how is the percent of charge state quantified?
>
> It it isn't . . . not without measurements. Many battery
> powered devices, especially laptops have smart batteries
> fitted with circuitry that measures the energy
> required to top off a battery and compares it with the
> energy demands of the computer. As the battery ages,
> the predicted endurance for the battery goes down even
> though the percentage of available capacity gets topped
> off to 100% each cycle.
>
------ SNIP--------
>
>
Message 4
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| Subject: | Re-juvinate a NiCad Battery? |
This post converted to html
Bob I'll put my comments in red after each of your paragraphs only because I
feel you have so much there AI don't want to miss anything.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: March 7, 2012 12:46 AM
Subject: Re: AeroElectric-List: Re-juvinate a NiCad Battery?
--> < <mailto:nuckolls.bob@aeroelectric.com> nuckolls.bob@aeroelectric.com>
At 07:09 PM 3/6/2012, you wrote:
>--> < <mailto:raymondj@frontiernet.net> raymondj@frontiernet.net>
>
>Question: How do you determine the percent charge on a battery pack.
>Is it by voltage or current or what. That's one of my pet peeves with
>rechargeables in everything. The batteries die from old age rather
>than from reaching the max number of cycles.
>
>Looking forward to hearing about this.
Okay, but you're probably not going to like it.
Some years ago I wrote an article about the economics
of using house branded AA cells in my airborne hardware.
We shall see but I've used the El cheapo Cells with great success. Of
course you don't expect to get as much service out of them as a more
expensive cell but the price difference is enough to make the cheapies a
great deal.
<http://aeroelectric.com/articles/AA_Bat_Test.pdf>
http://aeroelectric.com/articles/AA_Bat_Test.pdf
The thrust of the article went to in-flight reliability
of my battery powered hand held GPS and Comm radios
coupled with risk mitigation. One night over west
TX I found it necessary to change the four AA cells
out in my GPS receiver. During the fumbles with the
loose cells in the bottom of the flight bag, I dropped
one of the last good set of four cells on the deck.
That has happened to me in the car... I wouldn't consider changing cells in
mif flight without someone else to hold the plane straight. Generally my
flights are short and over familiar territory so VFR is the order of the
day.
We'll you can guess how THAT went. Had to turn
on the (ugh) VOR receivers and finish the trip.
This event started a train of thought to deduce
(1) the practicality of carrying a charger on
trips - another piece of hardware - and using
rechargeable batteries to be topped off before
flight . . . or simply putting new cells into the
device and pitching them when I got home.
I like the second idea. The reason is the drop in voltage on rechargables
is so different from conventional batteries. One second they look full
charged the next second they are dead flat.
I'd already wrestled with the ni-cads for my
flashguns and found that under less than ideal
conditions, I MIGHT be good for a several dozen
cycles . . . but when the flash gun craps in
the middle of a shoot and only one cell out of
the 4 was bad . . . the economics of hassle
was rearing an ugly head.
Been there to the extent I carried a good quality loaded battery tester with
me on shooting assignments... hopefully to weed out dead cells... Note the
word hopefully because sometimes you will get another two flashes only to
find out another battery is no dead.
I did try to establish sets of cells that
had been cap-checked in the last 10 cycles
or so and tried to keep cells of similar
capacity together. This also spotted cells
that were crapping out. I'd pitch them when
they dropped to 75% of capacity. That preventative
maintenance process improved on-the-job reliability
but it also took TIME that was not adding value.
When cheap cells became available on eBay, I
started dating the new cells when I put them
in service and pitched them at 6 months.
The cost of time to test them exceeded the
value of the cells!
Now you're right i don't like this... I wish I'd thought of dating the
cells because in real terms after six months the really become iffy. Thanks
for the idea.
Premium, highly advertised batteries in
one radio (or flashgun) was worth a gallon
of gas. So I began to wonder just how bad the
el-cheeso brands of AA alkaline battery could be.
In the article, you read how even the least
expensive cells (about 22 cents apiece)
offered VERY good value for contained energy.
We don't get any cells (AA) that cheap this far north, wish we did. The
discharge profile of alkaline cells is so different from that of NiCad cells
that even a cheap cell is better value than a NiCad especially if you don't
get the advertised 1000 recharges.. BTW did you ever find a person who
actually go anywhere near that number of recharges?
That's when I began the practice of installing
a fresh set of cells to go outbound, another
fresh set to come home. Fresh batteries
were dropped into the flight bag with a piece
of masking tape on them. I took the tape off
when the battery was installed. When I got
home un-tapped batteries were pressed into
other service and I never found myself fiddling
with batteries and battery box covers in flight.
That's what I started doing with my photoflashes on the ground. Then I took
the idea a step further. When I checked on the price of motorcycle tires I
decided I needed a tire to go around five years (3 mo Season/ yr) After
talking to a couple of tire vendors I came to the conclusion to buy
El-Cheapo tires (turns out they are actually made in the same factory as
more expensive units) and change them every year. That was in fact cheaper
but it also gave me fresh rubber every year. The type of riding I used to
do was not extreme in any sense of the word.
Wrestling with Ni-Cd or Ni-Mh arrays still
comes with the attendant uncertainties. Just
how good are these cells and how closely
matched are they for capacity? So to this day,
I still don't use rechargeable cells in flight
hardware or mission critical devices. The AA
cells are so cheap that keeping fresh ones in
the electrowhizzy takes very little time,
attention and/or expense.
I think you came to that conclusion faster than I did.
Now, the short answer to your question: You
need a device tailored to the task of fully
discharging a cell and reporting its contained
energy. I.e. a cap-checker. If you use a lot
of loose cells, this isn't too hard but if
the cells in question are in a soldered up
array inside a radio . . . you're flying
"blind" with respect to the real reliability
of the device.
As you say it is easy to deal with loose cells to discharge them but using
jumper wires it is possible to check and discharge individual cells in a
pack. In fact everything I've read warned not to allow one cell in a pack
to go so low in comparison to the other cells so that it will act as a
reverse potential. Therefore most of the things I've read suggested before
starting to discharge a pack check every cell in it and anything close to
flat should be shorted to prevent reverse charge. During the discharge the
cells should be checked often to short out those that are close to flat.
Once all the jumpers are in place and the pack itself is completely shorted
than the 24 hr starts to time the zero state of the pack.. I guess this
tells each battery what "0" should look like so there will be no memory
effect. Btw you don't recycle one cell in a pack If you flat one cell you
have to flat them all.
Cell arrays that are regularly excerised seem
to do real well. My Makita and DeWalt drill
batteries seem to be good for a year or more
but there's a fast charger nearby with another
battery of unknown quality setting in it.
Worst thing in the world is to leave the batteries with a full charge on it.
If you want to leave a battery for an extended period do so with that
battery flat. That is why when you get a new device the batteries are NEVER
charged! Daily use, especially complete use of batteries is a secret to
long life.
Rechargeable batteries are fine on the ground
but I'm reluctant to fly with them as part
of my failure tolerance team of electrowhizzies.
I agree especially if you are inclined to try to fool with the things in the
air.
Now for the best batteries I have ever seen. They are the batteries that
Kodak used to put in their disposable flash cameras. Most of those
batteries only saw a dozen flashes from micro flash units. So when they
came into the processing lab they were just about full. Each cell was
marked not for reuse but use them I certainly did and fifteen years after I
still have one or two that are still showing a full charge.. I have never
seen one of those batteries leak and generally they will out last the copper
top.. my second choice. The best part was they were free. I've visited
photo shops where they throw them out in the garbage. They shouldn't do
that but some places do and if you ask for them a lot of places will give
you a couple of dozen if they have them.
<http://aeroelectric.com/Pictures/Misc/Vacination_for_Dark_Panel_Syndrom.pdf
>
http://aeroelectric.com/Pictures/Misc/Vacination_for_Dark_Panel_Syndrom.pdf
Bob . . .
http://www.matronics.com/Navigator?AeroElectric-List
http://www.matronics.com/contribution
Message 5
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| Subject: | Re: Coolie Hat Switch |
Can't you just remove one from a $40 joystick?
David M
Etienne Phillips wrote:
> On 5 March 2012 06:50, <sam.marlow@roadrunner.com
> <mailto:sam.marlow@roadrunner.com>> wrote:
>
> <sam.marlow@roadrunner.com <mailto:sam.marlow@roadrunner.com>>
>
> Does anyone have a source for a roll your own coolie hat switch?
>
>
> Hi Sam
>
> Not cheap, but available from RS Components...
> *http://tinyurl.com/6u8ephu
> *
> Hope that helps!
> Etienne*
> *
> *
>
>
> *
--
Tell the truth. Be honest. Be responsible to and for yourself.
We want our freedoms back. Strike the illegal legislations called: 1) obamacare,
2) "Patriot (HA!) Act", and 3) 'presidential orders' that affect anyone besides
gubmnt worker bees.
Hate crime laws? Really? Thought police? Orwell would be proud.
Every gram of cocaine you buy from elsewhere contributes to an innocent being murdered
in Central and South America. Grow your own or Stop taking it.
Message 6
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| Subject: | Re-juvinate a NiCad Battery? |
Bob and others have mentioned trying the 3V/1Amp charge. What device
or battery do you use to provide the 3V - 1Amp charge?
Charlie Brame
RV-6A N11CB
San Antonio
----------------------------------------------------------------------------
> Time: 12:06:32 PM PST US
> From: "Noel Loveys" <noelloveys@yahoo.ca>
> Subject: RE: AeroElectric-List: Re-juvinate a NiCad Battery?
>
>
> The only way I've been able to determine if a battery is reaching
> its end of
> life is to use it. As a professional photographer I've had lots of
> experience with NiCads going dead at the wrong time (Murphy's law)
> so I used
> to always carry a couple of sets of alkalines for backup. A couple of
> things I found when batteries got to the point the just wouldn't
> hold a
> charge I would completely discharge them... keep a short across the
> terminals for 24 hr. Then hit them with a current of close to an amp
> with a
> voltage around 3V for about ten seconds... then recharge them
> normally. It
> seemed to rejuvenate somewhat and remove memory effect. The only
> batteries
> I tried this on were pretty well discharged at the time of applying
> the-------snip---------
Message 7
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| Subject: | Re: battery chargers |
The explosions I referred to were in the recreational vehicles (RV)
world, not in aviation. In mine, I was using a state-of-the-art mounted
charger ( as of 1986!) and did not watch the batteries closely enough so
definitely an over-charging situation caused this. I have since
replaced it with a more modern unit that has float charging capability.
The old one could vary charging rate a little but was always pushing
electrons into the batteries.
David M.
Robert L. Nuckolls, III wrote:
> At 11:40 AM 3/4/2012, you wrote:
>>
>> During charging, offgases are produced. If those gasses collect
>> somewhere, a spark can indeed set them off. Yes, thay can collect
>> inside the battery itself. Several RV batteries have been blown up
>> that way so I assume that it happens all over the place. Happened to
>> me once and my battery compartment is well ventilated.
>>
>> David M,
>
>
> Was there any sort of failure analysis done? Pictures
> taken? An RG battery stressed so hard as to produce
> gasses not contained in the mats combined with some
> spark-producing condition begs for answers as to root
<<<snip>>>
Message 8
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| Subject: | Re: Re-juvinate a NiCad Battery? |
Probably not.
David M.
Charles Brame wrote:
> <chasb@satx.rr.com>
>
> Is there anyway to rejuvenate an old NiCad battery? I have an iCOM
> hand held radio with a rechargeable battery pack. I assume the battery
> is a NiCad. The radio requires a 9.6v charge, but I can't get the pack
> charged above 9.25v. At that level I can listen to the radio, but
> cannot transmit. The charger that came with the radio puts out 10.4v
> when hooked to the battery, but the battery voltage won't increase
> even after a day or so of recharging. Is there any way to save this
> battery pack?
>
> Charlie Brame
> RV-6A N11CB
> San Antonio
>
>
--
Tell the truth. Be honest. Be responsible to and for yourself.
We want our freedoms back. Strike the illegal legislations called: 1) obamacare,
2) "Patriot (HA!) Act", and 3) 'presidential orders' that affect anyone besides
gubmnt worker bees.
Hate crime laws? Really? Thought police? Orwell would be proud.
Every gram of cocaine you buy from elsewhere contributes to an innocent being murdered
in Central and South America. Grow your own or Stop taking it.
Message 9
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| Subject: | Re: Coolie Hat Switch |
At 03:39 PM 3/7/2012, you wrote:
>
>I'll second that. I have some "delicate" switches that would benefit.
Now you dun it . . . got started on a good idea
last night and couldn't put it down until after 2
a.m.
Here's a first pass at an all solid state, two channel
relay deck and trim speed controller for a pair of
Ray-Allen trim actuators. It features adjustable
rates for both pitch and roll trim, dual inputs from
pilot and copilot stick grips, conflicting command
lockout, 10 to 30 volt input so it can be used on both
14 and 28v systems, AND . . . it will only load the
trim-switch contacts very lightly . . . about 20 mA.
http://www.aeroelectric.com/Misc/7299_Ray-Allen_Relay-Deck_Schematic.pdf
The parts values are not assigned yet so don't run
of an start buying parts. This is a preliminary look
at one concept for integrating those $22 switches
from Digikey into a Ray-Allen trim system.
I know it looks 'busy' . . . and not everyone will
want a full-up system. But the added expense of
including provisions for unneeded features is trivial.
The builder can take an assembly like this and craft
any one of many combinations of features.
At first blush, it looks like it would assemble onto
a 2.5 x 2.0 inch ECB with a 25 pin d-sub connector down
one side.
I need to quit 'playing' and get back on some committed
activities. I've got a young fellow who is interested
in learning how to lay out etched circuit boards. I'll
email him a copy of the drawing and see if he can get
all the parts on that size board. I know I can but
we'll give him a something to do over the up coming
spring break.
Bob . . .
Message 10
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| Subject: | Re: Re-juvinate a NiCad Battery? |
At 09:36 AM 3/8/2012, you wrote:
>
>Is it voltage that is measured. Does the manufacturer supply a
>voltage vs. % charge graph or table? Or is it derived experimentally?
>
>I understand that there are cost/benefit issues here, but my
>objective is to understand the process from a physics perspective
>for my own education.
Understand . . .
I don't think that open circuit terminal voltage
has a strong correlation to stored energy on the
metal cells. Least wise, I've not seen any charts
claiming to offer insight.
Bob . . .
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| Subject: | Re: Coolie Hat Switch |
wow looks great Bob!
---- "Robert L. Nuckolls wrote:
============
At 03:39 PM 3/7/2012, you wrote:
>
>I'll second that. I have some "delicate" switches that would benefit.
Now you dun it . . . got started on a good idea
last night and couldn't put it down until after 2
a.m.
Here's a first pass at an all solid state, two channel
relay deck and trim speed controller for a pair of
Ray-Allen trim actuators. It features adjustable
rates for both pitch and roll trim, dual inputs from
pilot and copilot stick grips, conflicting command
lockout, 10 to 30 volt input so it can be used on both
14 and 28v systems, AND . . . it will only load the
trim-switch contacts very lightly . . . about 20 mA.
http://www.aeroelectric.com/Misc/7299_Ray-Allen_Relay-Deck_Schematic.pdf
The parts values are not assigned yet so don't run
of an start buying parts. This is a preliminary look
at one concept for integrating those $22 switches
from Digikey into a Ray-Allen trim system.
I know it looks 'busy' . . . and not everyone will
want a full-up system. But the added expense of
including provisions for unneeded features is trivial.
The builder can take an assembly like this and craft
any one of many combinations of features.
At first blush, it looks like it would assemble onto
a 2.5 x 2.0 inch ECB with a 25 pin d-sub connector down
one side.
I need to quit 'playing' and get back on some committed
activities. I've got a young fellow who is interested
in learning how to lay out etched circuit boards. I'll
email him a copy of the drawing and see if he can get
all the parts on that size board. I know I can but
we'll give him a something to do over the up coming
spring break.
Bob . . .
Message 12
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| Subject: | BNC Shells touching |
My GNS-430W is a tight fit and the connections for the 4 antenna cables are very
close to each other. One of them is close to a cross cabin brace and the outside
of the BNC can touch this metal brace.
Is this a big deal, should I wrap the outsides of all the BNC connectors so that
they can't make metal to metal contact or does it matter.
Cheers
--------
Mike "Nemo" Elliott
RV-8A QB (Engine)
www.mykitlog.com/rvg8tor
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=368023#368023
Message 13
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| Subject: | Re-juvinate a NiCad Battery? |
or simply putting new cells into the
device and pitching them when I got home.
I like the second idea. The reason is the drop in voltage on
rechargables is so different from conventional batteries. One second
they look full charged the next second they are dead flat.
Which goes to my posting a few minutes ago considering
an inquiry about voltage versus state of charge on the
metal cells. The discharge curves are so flat (and I
believe temperature dependent) that the only reliable
measure of capacity is to run them down and count the
electrons
------------
When cheap cells became available on eBay, I
started dating the new cells when I put them
in service and pitched them at 6 months.
The cost of time to test them exceeded the
value of the cells!
Now you're right i don't like this... I wish I'd thought of dating
the cells because in real terms after six months the really become
iffy. Thanks for the idea.
Certainly your results may vary. But given that I
can buy a metal cell for about the same retail price as
a premium pink-bunny battery, I figure if I recharge
the things 10 times, I've received more than my money's
worth out of them. From that point on, it's gravy and
I've got no regrets for pitching a set of cells at first
sign of becoming an impediment to completion of task.
------------
We don't get any cells (AA) that cheap this far north, wish we did.
Buy them off eBay. Got any Sam's Clubs around? The Members
Mark AA cells are about $13 for a pack of 48 cells. Here's
a good mail order source for low cost premium cells
http://www.batteriesandbutter.com/DUBU.html
----------------
The discharge profile of alkaline cells is so different from that of
NiCad cells that even a cheap cell is better value than a NiCad
especially if you don't get the advertised 1000 recharges.. BTW did
you ever find a person who actually go anywhere near that number of recharges?
Don't think so. You might get that kind of result
in the lab . . . or maybe that's based on putting partially
discharged cells in the charger every night. We know that
an SVLA battery is good for about 100 deep discharge cycles
under ideal conditions and "thousands" of engine starts
when never called upon to supply a lot of energy. I suspect
that 1000 cycles thing is more advertising hype than real
world performance.
Worst thing in the world is to leave the batteries with a full charge
on it. If you want to leave a battery for an extended period do so
with that battery flat. That is why when you get a new device the
batteries are NEVER charged! Daily use, especially complete use of
batteries is a secret to long life.
I don't think my experience confirms this. Nickle cells have
such high discharge rates that I would be surprised to find
anything so equipped to run right out of the box.
Now for the best batteries I have ever seen. They are the batteries
that Kodak used to put in their disposable flash cameras. Most of
those batteries only saw a dozen flashes from micro flash units. So
when they came into the processing lab they were just about full.
Do you know that the disposable camera uses a nickle battery? I'd think
they would have to use alkaline or lithium to get any sort
of shelf life . . . and yes, running one roll of film through
the camera shouldn't even come close to discharging the cell(s).
Bob . . .
Message 14
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| Subject: | Re: Re-juvinate a NiCad Battery? |
At 10:27 AM 3/8/2012, you wrote:
>Bob and others have mentioned trying the 3V/1Amp charge. What device
>or battery do you use to provide the 3V - 1Amp charge?
There's nothing magic about either 3 volts or 1 amp. The task
is to see if you can burn away any whiskers that have grown
between the (+) and (-) plates to cause a short. I've used
a D-size, Ni-Cad which has a considerable short circuit delivery
characteristic. A computer grade, 200KuF electrolytic capacitor charged
up with one or two alkaline cells (1.5 to 3 volts) can be a potent
whisker blower. If you're successful in opening such faults,
it will happen in milliseconds.
Bob . . .
Message 15
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| Subject: | Re: Re-juvinate a NiCad Battery? |
Noel mentioned he read an article indicating the 40-70% range as
optimal. I was hoping the same article might have told how to determine
the charge state so the recommendations could be applied.
I use throw away batteries if I have a choice, but some of my tools only
have rechargeable packs. Doing what I can to maximize their life.
Thanks again,
Raymond Julian
Kettle River, MN
"And you know that I could have me a million more friends,
and all I'd have to lose is my point of view." - John Prine
On 03/08/2012 02:36 PM, Robert L. Nuckolls, III wrote:
> At 09:36 AM 3/8/2012, you wrote:
>>
>> Is it voltage that is measured. Does the manufacturer supply a voltage
>> vs. % charge graph or table? Or is it derived experimentally?
>>
>> I understand that there are cost/benefit issues here, but my objective
>> is to understand the process from a physics perspective for my own
>> education.
>
> Understand . . .
> I don't think that open circuit terminal voltage
> has a strong correlation to stored energy on the
> metal cells. Least wise, I've not seen any charts
> claiming to offer insight.
>
> Bob . . .
>
> *
>
>
> *
Message 16
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| Subject: | Re: Re-juvinate a NiCad Battery? |
Also, be advised that some of the dirt cheap batteries (and even some
full priced ones) are scams. They hold very little battery material and
last only a very short time. Think of the batteries that "are included"
with some of the cheap toys, for example. Some of those have made it
into the mainstream marketplace. Caveat Emptor.
David M.
Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 07:09 PM 3/6/2012, you wrote:
>>
>> Question: How do you determine the percent charge on a battery pack.
>> Is it by voltage or current or what. That's one of my pet peeves
>> with rechargeables in everything. The batteries die from old age
>> rather than from reaching the max number of cycles.
>>
>> Looking forward to hearing about this.
>
> Okay, but you're probably not going to like it.
> Some years ago I wrote an article about the economics
> of using house branded AA cells in my airborne hardware.
>
> http://aeroelectric.com/articles/AA_Bat_Test.pdf
>
> The thrust of the article went to in-flight reliability
> of my battery powered hand held GPS and Comm radios
> coupled with risk mitigation. One night over west
> TX I found it necessary to change the four AA cells
<<<snip>>>
Message 17
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| Subject: | Re: BNC Shells touching |
At 02:58 PM 3/8/2012, you wrote:
>
>My GNS-430W is a tight fit and the connections for the 4 antenna
>cables are very close to each other. One of them is close to a
>cross cabin brace and the outside of the BNC can touch this metal brace.
>
>Is this a big deal, should I wrap the outsides of all the BNC
>connectors so that they can't make metal to metal contact or does it matter.
Making contact isn't a big deal electrically but having
things bang together or rub mechanically can wear things
where they were not intended to wear.
Certainly some sort of buffer between otherwise touching
parts is a good idea. We wouldn't be allowed such liberties
in a TC airplane. As much as we'd like to think that
the machine is a rigid body, there are in-flight stresses
that can cause clearances to change under certain
conditions. I recall reading a spec at Beech on minimum
clearances both for access and separation.
But anything you stick in the gap might be the occasion
for considerable force to bear against the connectors
if that gap were to close for any reason.
In the best of all worlds, you'd strive for a half inch
or so of clearance.
Bob . . .
Message 18
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| Subject: | Re: Lamar DSX1240-1 Alternator |
At 10:16 AM 3/7/2012, you wrote:
>
>Modifying this circuit would be difficult. Much easier to delete the
>regulator in favor of an external one. Even easier still is selling
>the existing alternator and purchasing a more suitable one, which is
>what he has decided to do.
Good. It's is difficult sometimes to make
a useful trade between multiple solutions
without have a good grasp of the "big picture".
It's easy to be distracted by what one might
call false economics. E.g., a cousin of mine
was recipient of a nice Lincoln 4-door. He
was in tall cotton until something broke. My
first 'good' car was a '57 Chevy BelAire
with all the goodies. I too was riding high
until something broke. My next car was a '59
6-cyl, stick shift with a good heater and
crank windows. Best return-on-investment in
transportation I ever made. In spite of 1/2
the gas mileage, my total cost of ownership
per mile traveled was less than buying a
new Volkswagon Bug.
Availability of small externally regulated
alternators is limited. I just checked the
MPA catalog for single-tension, two-pivot
externally regulated alternators. Couldn't fine
anything under 90 amps. Doing the internal-to-
external mod isn't real difficult. How much
money does he have tied up in the alternator
he has?
Bob . . .
Message 19
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| Subject: | Re: Re-juvinate a NiCad Battery? |
At 03:55 PM 3/8/2012, you wrote:
>
>Also, be advised that some of the dirt cheap batteries (and even
>some full priced ones) are scams. They hold very little battery
>material and last only a very short time. Think of the batteries
>that "are included" with some of the cheap toys, for example. Some
>of those have made it into the mainstream marketplace. Caveat Emptor.
Yeah . . . you can find Ni-Cd and Ni-Mh AA cells rated
with over 2:1 differences in capacity. It would be
interesting to do the How Bad Can a Metal Battery Be?
experiment on some of these cells.
I've also noted that many so-called Ni-Cd "D" cells
are a bit . . . shall we say . . . light? They
are also rated in the 1500 to 2000 mAh range commensurate
with a "C" cell. I think these batteries would be
a disappointment too . . . a real Ni-Cad "D" is good
for about 4000 mAh.
The computer and DAS I used on the original battery
killer experiments bit the dust a couple of years ago.
I've got a new set of tools that I need to adapt to a
battery box that holds at least 8 cells for testing at
a time.
I'm debating whether to stay with the original testing
protocol for the AA alkaline cells that used a fixed
resistor. Certainly good enough for comparative
studies. I think I'd like to fit the test set with
software controlled loads . . . probably power fets.
This would let me run a wide range of discharge currents.
It would also allow modulation of the test current
during a discharge cycle to measure the cell's internal
resistance. Dynamic loads would also let me discharge
in a constant resistance, constant current or constant
power modes. I need to talk to my software guy and see
if he's up to making this hardware 'hum'. I'm not going
to have time to do it for awhile.
But you're quite right. What's marked on the label may
not be all it claims to be.
Bob . . .
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