Today's Message Index:
----------------------
1. 03:46 AM - Re: Re: ADS-B and Transponder antenna... (Robert L. Nuckolls, III)
2. 09:46 AM - Re: Lead Acid Batteries ()
3. 08:14 PM - DIY LED landing light -- Wing skin as heat sink? (Finn Lassen)
4. 10:51 PM - Ai - Blue Prism Training in Bangalore | Certification | Onli (masko4224)
Message 1
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| Subject: | Re: ADS-B and Transponder antenna... |
At 10:45 AM 10/25/2020, you wrote:
>
>There's an RF Engineer who works for Tektronix, Alan Wolke, who has
>a very good YouTube channel. Among other things, he's recently been
>posting a series of videos on how to use the nanoVNA for various measurements.
>
>Note that the following playlist does not list the videos in the
>order they were posted, but I would recommend at least watching #312
>and #313 before any others.
>
>https://www.youtube.com/playlist?list=PL4ZSD4omd_AylEyNCQYR3RcEb0olukPEJ
just had a chance to review the gentleman's work . . . great find
Eric . . . thanks for the head's up!
Bob . . .
Message 2
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| Subject: | Lead Acid Batteries |
Thanks for the information on lead acid batteries...it seems that the Sears Die
Hard battery was never affected by cold temperatures (commercials never lie):
https://www.youtube.com/watch?v-SSLnwVRwA
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com <owner-aeroelectric-list-server@matronics.com>
On Behalf Of Kelly McMullen
Sent: Thursday, October 29, 2020 8:18 PM
Subject: Re: AeroElectric-List: Lead Acid Batteries
--> <kellym@aviating.com>
Hmmm, my wife is older than I am(and a pilot), and I worked on hard rubber case
batteries in both aircraft and autos. In fact battery recycling shops were common
that melted the lead after cleaning of old acid, made new plates, and installed
in the rubber cases. Of course many are now super fund sites. IIRC the
Diehard series was one of the first polyethylene or propylene, back in the late
60's.
Having an aircraft on open ramp in Fairbanks in the 70s, with no power at tiedowns,
had to pull battery, take home and occasionally charge.
Kelly
On 10/29/2020 8:00 PM, Matthew S. Whiting wrote:
> --> <m.whiting@frontier.com>
>
> I dont think any wives alive today were also around when batteries were last
made with hard rubber cases that contained carbon and were slightly porous.
>
> Yes, a fully charged battery is good to somewhere around -80 F, but a fully discharged
battery will freeze around 20 F. I always keep mine inside in the winter
or on a battery maintainer. And inside is best if you may need to install
the battery and use it as it will crank much better while warm than when sitting
outside at -40.
>
> Sent from my iPad
>
>> On Oct 29, 2020, at 10:48 PM, Kelly McMullen <kellym@aviating.com> wrote:
>>
>> <kellym@aviating.com>
>>
>> It was true when old wives were young, and battery cases were made of hard rubber.
Once the switch was made to polypropylene or equivalent, it was no longer
true. Battery's freeze point is dependent on state of charge. Discharged it
can be close to freezing, but if fully charged it is somewhere near -70F. When
I had plane in those temps, I made sure battery was removed before reaching
-40.
>>
>>> On 10/29/2020 6:19 PM, Matthew S. Whiting wrote:
>>> Yes, the sitting on concrete is an old wives tale.
>>> Allowing a lead acid battery to completely discharge will definitely shorten
its life as more lead sulphate will form than can be reversed when the battery
is charged. And if it is cold out, it will freeze which will really shorten
its life quickly as the case will often split and let the acid (well mostly
water once fully discharged) leak out once it thaws.
>>> Matt
>>> Sent from my iPad
>>>>> On Oct 29, 2020, at 8:54 PM, billhuntersemail@gmail.com wrote:
>>>>
>>>>
>>>>
>>>> Hi All,
>>>>
>>>> I hope everyone is doing well.
>>>>
>>>> I have a couple of questions about lead acid batteries
>>>>
>>>> First is the old tale that if you store a lead acid battery on the concrete
floor it will discharge so keep it on a work bench or on wood blocksis that
actually true or have I just been snipe hunting all of these years (decades)?
>>>>
>>>> Second question is about allowing a lead acid battery to discharge all the
way down to zeroor if it had gotten severely discharged a few timesit will no
longer be serviceable. Is this accurate? If so why would a good battery become
junk just because you left the lights on and drained it down to zero?
>>>>
>>>> Third question is what is the difference between a car battery and a marine
battery/ deep cycle battery?
>>>>
>>>> Thanks everyone!!!
>>>>
>>>> Bill
>>>>
>>
>>
>>
>
>
>
>
>
Message 3
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| Subject: | DIY LED landing light -- Wing skin as heat sink? |
Might say the most critical thing for LED life and high lumens output is
conducting heat away from the LED.
That usually means attaching heavy heat sinks.
Could we save weight by using the wing skin as a heat sink?
I understand it would present problems in adjusting (pointing) the light.
But, could we bond/attach the LED to a (alum?) plate that is then
bonded/riveted/screwed to the leading edge wing skin?
Let's say we use a 100W LED (~13,000 lumens). We'd have to remove 70 to
80W of heat from the LED. LED doesn't like more than 150C and it would
be better to keep it cooler. LED area 34x34mm.
I don't have a good grasp of thermal conductivity (conductance?). How
thick would the mount plate have to be? How much area would be needed
where the mount plate contacts the wing skin (using some kind of heat
sink compound/adhesive between the plate and skin)?
Am I right in assuming the plate has to be thickest were the LED is
mounted and then taper down in thickness as it expands out in width and
height?
Perhaps tapered layers of carbon fiber (with thermal epoxy) would be
better as the LED mount plate? (After a diamond, graphene or graphite
apparently has the best thermal conductivity.)
Any (thermal) engineers here that could enlighten me?
Finn
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Message 4
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| Subject: | Ai - Blue Prism Training in Bangalore | Certification |
| Onli
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