Today's Message Index:
----------------------
1. 03:32 AM - Re: new kids on the block (David Carter)
2. 06:28 AM - Re: new kids on the block (jdpnm)
3. 07:13 AM - Re: Re: new kids on the block (Jared Yates)
4. 07:42 AM - Re: Primary Power Diagram RV-14 (Mudfly)
5. 08:08 AM - Re: Re: new kids on the block (Tim Olson)
6. 08:32 AM - Re: Re: new kids on the block (Robert L. Nuckolls, III)
7. 10:25 AM - Re: new kids on the block (Sebastien)
8. 10:38 AM - Re: Re: new kids on the block (Robert L. Nuckolls, III)
9. 10:49 AM - Re: Re: new kids on the block (Charles Kuss)
10. 12:14 PM - Thermocouple test (Dave Saylor)
11. 12:55 PM - What's all this Lithium Specific Battery Charger stuff anyhow? (Robert L. Nuckolls, III)
12. 01:20 PM - Fusible link wire (jdpnm)
13. 01:55 PM - Re: Thermocouple test (Robert L. Nuckolls, III)
14. 02:16 PM - PIDG vs F crimp uninsulated terminals (Matthew S. Whiting)
15. 02:29 PM - Re: Re: Primary Power Diagram RV-14 (Werner Schneider)
16. 02:31 PM - Re: Thermocouple test (Dave Saylor)
17. 03:10 PM - Re: What's all this Lithium Specific Battery Charger stuff anyhow? (Sebastien)
Message 1
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| Subject: | Re: new kids on the block |
Bob,
Have you taken a look at the Noco chargers? I've used their Genius 5 on my
PC680 AGM for some time now, and it seems to do a good jo.
https://no.co/products/charging/genius
Regards,
David
On Mon, Mar 13, 2023 at 9:52 PM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> I have been a devoted user of both Battery Minder and
> Battery Tender products for the charging/maintenance
> of wet, svla, and automotive lithium batteries for
> decades.
>
> Got a half dozen or more of these things in my
> shop. While their charge rate is pedestrian (less
> than 1.0A) they DO ultimately top-off a lead-acid
> device and subsequently MAINTAIN it indefinitely.
>
> Sadly, my go-to favorites have been creeping up in
> price for some time which has prompted me to put
> a dip-stick into the emerging market of battery
> charger/maintainers.
>
> I've had one of these things for awhile . . .
>
> https://tinyurl.com/3e48emj4
>
> . . . and used it to conduct some battery performance
> tests as well as mitigate some battery issues on
> my vehicles.
>
> I can report that they do a credible (and much
> stronger) job of battery charging compared
> to my 'wall warts' (8 amps). They've got some
> 'features' that presumably favor seasonal
> variation in battery performance as well as
> a 'pulse repair' mode.
>
> I've not yet confirmed that these 'extra' features are
> valuable but I can tell you that the charge/maintenance
> modes for wet and SVLA technologies are solid.
> I'll have some data plots to share in future but
> in the mean time, the current price for this
> product is very competitive with the BatteryMinder/
> BatteryTender alternatives.
>
> I've also acquired a piece of test equipment
> that is of exceptional utility/value . . .
> watch this space.
>
>
> Bob . . .
>
> ////
> (o o)
> ===========o00o=(_)=o00o========
> < Go ahead, make my day . . . >
> < show me where I'm wrong. >
> ================================
>
> In the interest of creative evolution
> of the-best-we-know-how-to-do based
> on physics and good practice.
>
--
---
David Carter
david@carter.net
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| Subject: | Re: new kids on the block |
Looks like Amazon has same thing for a little less
https://www.amazon.com/Automotive-Battery-Automatic-Motorcycle-YONHAN/dp/B089VRXB2W/ref=sr_1_9?keywords=Intelligent+Automatic+Car+Battery+Charger+12%2F24V+8A+Pulse&sr=8-9
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=510396#510396
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| Subject: | Re: new kids on the block |
I have been testing similar chargers with good results. It is worth noting
that some have a trickle/float mode after the main charge, and some do not.
For maintaining a battery, the trickle mode is essential. For one-time
charging, no biggy. I wish it was selectable with a switch.
On Tue, Mar 14, 2023, 09:32 jdpnm <jdp3322@gmail.com> wrote:
>
> Looks like Amazon has same thing for a little less
>
> https://www.amazon.com/Automotive-Battery-Automatic-Motorcycle-YONHAN/dp/B089VRXB2W/ref=sr_1_9?keywords=Intelligent+Automatic+Car+Battery+Charger+12%2F24V+8A+Pulse&sr=8-9
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=510396#510396
>
>
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| Subject: | Re: Primary Power Diagram RV-14 |
I have updated my Primary Power System diagram.
Changes made:
* Removed two shunts and replaced with one hall effect sensor.
* Moved stdby alt field feed wire from avionics/essential bus to hot bat
bus.
* Moved essential bus relay firewall fwd.
*Removed current limiter between bat contactor and essential bus relay.
*Added 4-post bus bar between battery contactor and main power bus.
*Reduced wire size from 4awg to 6awg on pri alt b lead.
Pending:
*Possible removal of avionics switch and relay.
Questions:
* I moved the essential bus relay firewall fwd. My thinking was it
provides improved crash protection. Is this a good plan, or was the
30 amp current limiter I had in place on previous diagrams sufficient and keep
the
relay aft of firewall? Do these relays hold up well FWF?
* The stby alt fied wire is now fed from the hot bat bus. I show a 20awg
FLW protecting that wire. Is this ok for through the firewall wires?
*Is a FLW from the essential bus relay to the bus needed?
*I'm still figuring out relay types. I see most use a DPDT . For my setup
could I use a SPST? I'm looking at N.O. at 30 amp models.
Recommendations?
* I added a 4-post bus bar (Blue Sea System 2315 100 amp) between
bat contactor and main power bus. Reasoning was based on the fuse
block I'm using (Eaton 15711-20-21A) has one stud for power
connections.
My setup requires three
wires; main power bus feed, pri alt field flw, and avionics relay feed.
I don't see a good way to make those connections on that single stud. I have
a good location for the
4-post bus bar that will allow for clean wire runs and easy serviceability.
Thoughts?
Thanks, Shawn
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=510398#510398
Attachments:
http://forums.matronics.com//files/primary_power_system_3_14_23_121.pdf
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| Subject: | Re: new kids on the block |
Good find, on Amazon. At least there you can read reviews and after
reading the 1 star reviews, I decided to pass on it.
I have had good luck with the Ctec chargers, personally. But they're
nowhere near the price.
Tim
On 3/14/23 8:27 AM, jdpnm wrote:
>
> Looks like Amazon has same thing for a little less
> https://www.amazon.com/Automotive-Battery-Automatic-Motorcycle-YONHAN/dp/B089VRXB2W/ref=sr_1_9?keywords=Intelligent+Automatic+Car+Battery+Charger+12%2F24V+8A+Pulse&sr=8-9
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=510396#510396
>
>
>
Message 6
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| Subject: | Re: new kids on the block |
At 09:13 AM 3/14/2023, you wrote:
>I have been testing similar chargers with good results. It is worth
>noting that some have a trickle/float mode after the main charge,
>and some do not.
Yes. All batteries are plagued with a self-discharge
characteristic will ultimately bring stored energy
down to a level that promotes internal destruction
of the chemistry.
It would be interesting to know your experience
with the various products.
The ideal charger has a MAINTENANCE mode that supports
the battery's terminals to a voltage just above the
open circuit voltage. Well maintained batteries on
my bench present an O.C. voltage on the order of 12.9
volts. My maintainers support shelved batteries at 13.2
to 13.5 volts. Just enough to support self discharge
currents but not enough to ADD energy to the chemistry
thus leading to overcharge.
The original concept of a 'trickle' charge was to
constantly push some small charge current into the
battery . . . say 100 mA or so. But I've seen legacy
trickle chargers that put out 500 mA or more.
Yeah, they prevented self discharge but eventually
cooked the battery.
>For maintaining a battery, the trickle mode is essential.
>For one-time charging, no biggy. I wish it was selectable with a switch.
The charger I cited has a mode select switch that
claims to differentiate between wet and SLVA devices.
Not sure the physics really supports such an idea
but I'll continue to exercised this product and
gather more data.
Unlike the 'wall wart' devices, this one is a REAL
charger having an 8A rate at 12v and 4A rate at
24v. Further, it tapers down sharply at some
plateau and enters a 'top off' mode of approx
2 hours at something on the order of 1A with a
cutoff that appears to be about 0.8A.
I've got a plot of this behavior which I'll go
get later this morning (need to see up file
sharing over the WiFi to replace data-transfer-via-
thumbdrive!)
The important thing is that if you load a battery
under maintenance for a few seconds, the charger
reverts to a top-off mode and replaces expended
energy.
This behavior is consistent with a true MAINTAINER
as opposed to the legacy open-loop, trickle charge
philosophy of yesteryear.
I'm setting up a new test facility out in the
mess-making shop to explore the physics of things
like batteries, chargers and small alternators.
Will update the List as new information is secured.
I've got a couple of group 4, 100AH batteries on the
shelf that I've been storing for a client who seems to
have abandoned the goals for having purchased the
batteries.
They are new, old stock, sustained on maintainers for
about three years. I'm interested in seeing what
shape these batteries are in for having sat so
long! Need to finish my 50A discharge adapter
for the WestMountain CBA.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.
Message 7
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| Subject: | Re: new kids on the block |
The NOCOs are way overpriced. Bob's example does a better job at 1/6th the
price.
Bob, have you found a similar charger for lithium batteries?
On Tue, Mar 14, 2023 at 3:35=AFAM David Carter <david@carter.net> wro
te:
> Bob,
>
> Have you taken a look at the Noco chargers? I've used their Genius 5 on m
y
> PC680 AGM for some time now, and it seems to do a good jo.
>
> https://no.co/products/charging/genius
>
> Regards,
> David
>
> On Mon, Mar 13, 2023 at 9:52 PM Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com> wrote:
>
>> I have been a devoted user of both Battery Minder and
>> Battery Tender products for the charging/maintenance
>> of wet, svla, and automotive lithium batteries for
>> decades.
>>
>> Got a half dozen or more of these things in my
>> shop. While their charge rate is pedestrian (less
>> than 1.0A) they DO ultimately top-off a lead-acid
>> device and subsequently MAINTAIN it indefinitely.
>>
>> Sadly, my go-to favorites have been creeping up in
>> price for some time which has prompted me to put
>> a dip-stick into the emerging market of battery
>> charger/maintainers.
>>
>> I've had one of these things for awhile . . .
>>
>> https://tinyurl.com/3e48emj4
>>
>> . . . and used it to conduct some battery performance
>> tests as well as mitigate some battery issues on
>> my vehicles.
>>
>> I can report that they do a credible (and much
>> stronger) job of battery charging compared
>> to my 'wall warts' (8 amps). They've got some
>> 'features' that presumably favor seasonal
>> variation in battery performance as well as
>> a 'pulse repair' mode.
>>
>> I've not yet confirmed that these 'extra' features are
>> valuable but I can tell you that the charge/maintenance
>> modes for wet and SVLA technologies are solid.
>> I'll have some data plots to share in future but
>> in the mean time, the current price for this
>> product is very competitive with the BatteryMinder/
>> BatteryTender alternatives.
>>
>> I've also acquired a piece of test equipment
>> that is of exceptional utility/value . . .
>> watch this space.
>>
>>
>> Bob . . .
>>
>> ////
>> (o o)
>> ===========o00o=(_)=o00o======
==
>> < Go ahead, make my day . . . >
>> < show me where I'm wrong. >
>> =======================
=========
>>
>> In the interest of creative evolution
>> of the-best-we-know-how-to-do based
>> on physics and good practice.
>>
> --
> ---
> David Carter
> david@carter.net
>
Message 8
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| Subject: | Re: new kids on the block |
At 10:07 AM 3/14/2023, you wrote:
>
>Good find, on Amazon. At least there you can read reviews
>and after reading the 1 star reviews, I decided to pass on it.
The 1-star comments are often problematic.
OFTEN short on DATA that promotes meaningful
analysis. One such review blamed a near-miss
house fire on the charger. He included a photo
of an extension cord powering the charter where
heating effects caused catastrophic damage to
the cord's receptacle.
Joints at connectors always fail in the female
pin . . . that's were pressure good conductivity
is maintained on the mated members. This charger
puts out about 100W when puffing hard to charge
a battery. Even at 50% efficiency, input current
to the charger would be on the order of 1.6A.
For destruction to have occurred at that current
level suggests a severely compromised receptacle
on the end of the cord.
Read another 1-star beef complaining that the
charger would not pick up the task on a 24v
battery discharged to less than 10V. Of course
the smart charger deduced this to be a 12v battery
and 'topped it off' at 14.5 volts! It pays to
read the instructions.
To be sure, there are MANY battery maintenance
products out there with satisfactory performance.
I'm sure that BatteryTenders and BatteryMinders
have worthy competitors for performance.
But there is no analog to Consumer's Report on
battery maintenance products so we're kinda stuck
with LEARNED reviews of a few products by COGNIZANT
OBSERVERS.
So thank you Tim . . . and any others who care
to search around in the marketplace for good
value.
Here's the 'first look' plot I promised on the charger's
performance:
https://tinyurl.com/2p92yzjv
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.
Message 9
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| Subject: | Re: new kids on the block |
The unit linked below is for 220/240 volt input.
On Tuesday, March 14, 2023, 09:37:38 AM EDT, jdpnm <jdp3322@gmail.com>
wrote:
Looks like Amazon has same thing for a little less
https://www.amazon.com/Automotive-Battery-Automatic-Motorcycle-YONHAN/dp/B0
89VRXB2W/ref=sr_1_9?keywords=Intelligent+Automatic+Car+Battery+Charger+
12%2F24V+8A+Pulse&sr=8-9
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=510396#510396
-
S -
WIKI -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
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| Subject: | Thermocouple test |
I got into a little debate at work the other day about testing
thermocouples. The task is to check for a millivolt rise while heating
each probe. My coworker was checking for resistance and got a little
defensive when I pointed out that it calls to check for millivolts. The
justification was "well, I use resistance". He was seeing a change in
resistance with heat applied. I was seeing a change too, but I was looking
at millivolts.
Now I'm wondering. Does checking for resistance give a less valid result
than checking for voltage? The instructions just say to look for a rise in
voltage, not any specific value. Does a "rise" in millivolts give any
better information than a change in resistance? FWIW, the resistance was
rising when heat was applied as well.
The system consists of four thermocouples in parallel. Application is a
helicopter engine.
Thanks for your help,
Dave
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| Subject: | What's all this Lithium Specific Battery Charger stuff |
anyhow?
At 12:24 PM 3/14/2023, you wrote:
>The NOCOs are way overpriced. Bob's example does a better job at
>1/6th the price.
>
>Bob, have you found a similar charger for lithium batteries?
There are lithium and then there are LITHIUM batteries.
I've oft pondered the contradictions in performance
claims by the various purveyors of lithium products.
There are dozens of batteries that are simple
assemblies of cells stacked 4-high proposed
for service in a 14v system. They claim
to be drop-in replacements for wet or SVLA
products.
Okay, if the thing is claimed to live happily
in a lead-acid environment, then what's
this "special lithium charger" stuff all about?
Then there are products that offer battery
management systems within the battery itself.
The term "BMS" does not offer an industry
wide description of form and function.
Products that seek to assure consumers of
100% compatibility with the lead-acid world
often include electronics adding substantially
to the cost of the battery! Yet, there are as
many (if not more) products offered with NO
built in electronics. Some do offer a
cell-balancing connector. Ebay and Amazon
are replete with cell-balancing modules
that cater to the DIY battery-array market.
I'll call your attention to the figures here
on my website:
https://tinyurl.com/mw4fz3pf
One figure illustrates a family of capacity
vs. charge voltage plots for an A123
LiFePO4 cell. Note the battery performance
when charged at various termination voltages
ranging from 3.3 to 3.7 volts. In a 4-stack
array intended for 14v systems, these voltages
correspond to system voltages of 13.2 to 14.8
volts.
Note that cell capacity is essentially maxed
out with a charge voltage of 3.4 Volts/Cell
(13.6V system) with no significant improvement
above that.
The other image is a snapshot of specs for
a well known variety of LiFePO4 cells that
state a max charging voltage of 4.2 until the
current drops below 100mA. This would be a system
voltage of 16.8 Volts!
Perhaps this offers a reason for the success
of the many bare-foot, 4-stack engine cranking
products out there. As long as system voltage
is greater than 13.6 (but less than 16.8),
the battery has a high order probability of
a useful life.
So, what's all this lithium specific charger
stuff about? The charger we've been discussing
in this thread tops out at just under 15V. No
red flags there.
In the BMS camp for lithium products, we're
told that the battery is a plug-n-play replacement
of the EXISTING wet or SVLA battery. Rest assured
that the BMS will protect your substantial investment
from alternator malfeasance . . . except that its
not clear to me that the legacy lead-acid system
set up to charge and 14.2 to 14.8 volts is something
to be worried about.
So that's a long introduction to my response to
your question. Unless someone has DATA to suggest
otherwise, I'm of the not-so-humble opinion that
lithium specific chargers are in the same class
as battery desulfators. There are dozens of patents
on desulfation processes NONE of which are accompanied
by repeatable laboratory grade tests that demonstrate
efficacy of their claims.
I've got a EarthX battery on the bench that's
be maintained by one of my venerable BatteryMinders
for about 10 years. That reminds me, I think I'll
run a new cap and load check on the little feller.
Don't have an airplane to run it in but it's jump
started a dozen or so vehicles over the years!
The one thing I've not yet mentioned is the 'cell-
balancing' feature suggested in some battery
management philosophies.
Cell balancing becomes a significant concern as
the cells age. If the internal impedance and/or voltage
vs. charge current one layer in the 4-stack array
rises significantly over the others, it's capacity has
been depressed. So while its brothers are still actively
taking on more Joules of energy, the 'weak sister' is
at risk for exacerbated damage due to over-charging.
A cell balancing system places a dummy-load resistor
across a compromised layer of cells to reduce the
risks to the cells.
Given what we've observed of the lithium art and
science over the last decade, I'll suggest that cell
balancing is probably not applicable to aircraft
applications. Keep in mind that the majority market
for batteries is populated with customers who routinely
deep-discharge their batteries and flog 'em until they
don't get up and hunt any more.
We airplane guys are intently interested in
CAPACITY of a battery compared against DESIGN
GOALS for Plan-B endurance in battery only
ops. The rule of thumb for battery replacement
is to take it out of service at 80% of new
or when battery-only endurance goals are not
satisfied.
In both SVLA and Lithium worlds, a battery is
likely to still be cranking an engine when it's
time to replace and before cell balancing becomes
a significant issue.
That's kind of a long winded answer to your
question but hopefully gives you understanding
that supports future decisions.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.
Message 12
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| Subject: | Fusible link wire |
Standard Motor parts sells Fusible link wire in 20ga 25ft roll.
Retailer are Rock Auto $8+ ship
Amazon $10.50 free shipping
Walmart.com $10.37 free shipping
ebay $15.42 free shipping
Part number is Standard Motor Products CW20F Fusible Link Wire
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=510406#510406
Message 13
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| Subject: | Re: Thermocouple test |
At 02:13 PM 3/14/2023, you wrote:
>I got into a little debate at work the other=C2
>day about testing thermocouples.=C2 The task is
>to check for a millivolt rise while heating each
>probe.=C2 My coworker was checking for resistance
>and got a little defensive when I pointed out
>that it calls to check for millivolts.=C2 The
>justification=C2 was "well, I use
>resistance".=C2 He was seeing a change in
>resistance with heat applied.=C2 I was seeing a
>change too, but I was looking at millivolts.
>
>Now I'm wondering.=C2 Does checking for
>resistance give a less valid result than
>checking for voltage?=C2 The instructions just
>say to look for a rise in voltage, not any
>specific value.=C2 Does a "rise" in millivolts
>give any better information than a change in
>resistance?=C2 FWIW, the resistance was rising when heat was applied as
well.
>
>The system consists of four thermocouples in
>parallel.=C2 Application is a helicopter engine.
The procedure(s) you've described are gross
functionality tests to (1) show continuity across
the thermocouple and (2) verify that the thing
on the other end is indeed a thermocouple. I.e.
marked change of voltage with temperature.
These tests say nothing about calibration or accuracy
although if there is continuity, then there is little doubt
as to accuracy. Thermoelectric effects are kinda
molecular and not subject to 'drift'.
4 thermocouples in parallel, assuming similar
environments within the engine, will yield an
AVERAGE temperature measurement for the 4
items of interest. At the same time, testing
one of the 4 while still parallel connected
to the other 3 greatly reduces the sensitivity
of effects attributable to the one.
But you are correct . . . Thermocouples are
VOLTAGE generators with known scale factors
(millivolts per degree C change). An ohmmeter
deduces resistance of a conductor path by measuring
the voltage drop through that path when it's
'excited' by some test bias. Since the ohmmeter
is translating voltage values to displayed
resistance, it stands to reason that heating
a thermocouple connected to an ohmmeter would
manifest in a change of resistance reading.
But again, while this test says, "yeah, there
may be a thermocouple out there I'm seeing,"
it's no better or worse test of function than
simply looking for the generated voltage. It's
VOLTAGE that offers knowledge about what's
happening in the engine.
Bob . . .
////
(o o)
===========o00o=(_)=o00o=======
=
< Go ahead, make my day . . . >
< show me where I'm wrong. >
========================
========
In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.
Message 14
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| Subject: | PIDG vs F crimp uninsulated terminals |
Bob,
I read your preference for PIDG terminals in your AeroElectric Connection book.
I am curious as to your preference for these as compared to F crimp uninsulated
terminals.
Ive always preferred the latter as I generally label my wirings using printed shrink
wrap and that makes a neater installation over the uninsulated terminals
and provides decent insulation. I simply find the uninsulated connectors easier
to inspect for a good crimp and smaller in OD which is nice on small gauge
wires.
I see that both B & C and SteinAir only carry the insulated style terminals, but
Ive never seen a discussion as to pros and cons as compared to uninsulated F
crimps.
Thanks,
Matt
Sent from my iPad
Message 15
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| Subject: | Re: Primary Power Diagram RV-14 |
On 04.03.2023 16:22, Robert L. Nuckolls, III wrote:
> At 02:38 PM 3/2/2023, you wrote:
>> <shawntedwards@hotmail.com>
>>
>> I have made changes to the Primary Power system design.=C2- I switche
d
>> from CBs to fuses as recommended my several.=C2-=C2- I eliminated o
ne bus
>> completely, and moved the Hot Batt Bus firewall fwd . . .
>
>
> =C2-=C2- I note that you're planning a rather sophisticated
> =C2-=C2- (and expensive) regulator for the standby alternator.
> =C2-=C2- You also wire it per B*C suggestions to power regulator
> =C2-=C2- from the bus which is not firmly connected to the
> =C2-=C2- b-lead of that same alternator.
>
> =C2-=C2- In Z101 I suggest a dirt-cheap regulator for standby
> =C2-=C2- service powered from the battery bus. Probability of
> =C2-=C2- needing the stand-by alternator in flight is very
> =C2-=C2- low. It gets pre-flight tested and then 'stowed'.
> =C2-=C2- No o.v. protection necessary . . . the likelihood of
> =C2-=C2- an o.v. event less than 4 hours after a pre-flight
> =C2-=C2- test is low on a system already unlikely to
> =C2-=C2- see service under 'duress'.
>
> =C2-=C2- Further, powering from the battery bus keeps
> =C2-=C2- the s/b alternator available in every situation.
>
Hi Bob,
I'm planing as well a Z101 version with the SB1B-14 instead of the cheap
regulator.
Reason is, that with the SB1B-14 I can just switch both alternators on
for a single pilot IFR plane, so to lower the workload in case of (rare)
failure of the primary alternator.
I guess there is no drawback on that except price (which is a small
percentage of the avionics price :), but the Voltage sense taken of the
battery bus (Shawn you still have that on the essential).
I still would go along the 101 route, having both alternators on a
separate switch and the essential bus feed via a diode matrix and
alternate feed path via relay direct from battery.
I will share all of this in a few weeks when I have sorted out all
details in a separate entry in this list.
Am I right with my thinking on this?
Thanks for your support (I'm able to profit from since 23 years :)
Cheers Werner
Message 16
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| Subject: | Re: Thermocouple test |
Thanks Bob, that's just the kind of answer I was looking for. We'll all
talk about this and maybe each learn a bit. --Dave
On Tue, Mar 14, 2023 at 1:57=AFPM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 02:13 PM 3/14/2023, you wrote:
>
> I got into a little debate at work the other=C3=82 day about testing
> thermocouples.=C3=82 The task is to check for a millivolt rise while hea
ting
> each probe.=C3=82 My coworker was checking for resistance and got a litt
le
> defensive when I pointed out that it calls to check for millivolts.=C3=82
The
> justification=C3=82 was "well, I use resistance".=C3=82 He was seeing a
change in
> resistance with heat applied.=C3=82 I was seeing a change too, but I was
> looking at millivolts.
>
> Now I'm wondering.=C3=82 Does checking for resistance give a less valid
result
> than checking for voltage?=C3=82 The instructions just say to look for a
rise
> in voltage, not any specific value.=C3=82 Does a "rise" in millivolts gi
ve any
> better information than a change in resistance?=C3=82 FWIW, the resistan
ce was
> rising when heat was applied as well.
>
> The system consists of four thermocouples in parallel.=C3=82 Application
is a
> helicopter engine.
>
>
> The procedure(s) you've described are gross
> functionality tests to (1) show continuity across
> the thermocouple and (2) verify that the thing
> on the other end is indeed a thermocouple. I.e.
> marked change of voltage with temperature.
>
> These tests say nothing about calibration or accuracy
> although if there is continuity, then there is little doubt
> as to accuracy. Thermoelectric effects are kinda
> molecular and not subject to 'drift'.
>
> 4 thermocouples in parallel, assuming similar
> environments within the engine, will yield an
> AVERAGE temperature measurement for the 4
> items of interest. At the same time, testing
> one of the 4 while still parallel connected
> to the other 3 greatly reduces the sensitivity
> of effects attributable to the one.
>
> But you are correct . . . Thermocouples are
> VOLTAGE generators with known scale factors
> (millivolts per degree C change). An ohmmeter
> deduces resistance of a conductor path by measuring
> the voltage drop through that path when it's
> 'excited' by some test bias. Since the ohmmeter
> is translating voltage values to displayed
> resistance, it stands to reason that heating
> a thermocouple connected to an ohmmeter would
> manifest in a change of resistance reading.
>
> But again, while this test says, "yeah, there
> may be a thermocouple out there I'm seeing,"
> it's no better or worse test of function than
> simply looking for the generated voltage. It's
> VOLTAGE that offers knowledge about what's
> happening in the engine.
>
> Bob . . .
>
> ////
> (o o)
> ===========o00o=(_)=o00o======
==
> < Go ahead, make my day . . . >
> < show me where I'm wrong. >
> =======================
=========
>
> In the interest of creative evolution
> of the-best-we-know-how-to-do based
> on physics and good practice.
>
Message 17
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| Subject: | Re: What's all this Lithium Specific Battery Charger |
stuff anyhow?
All agreed Bob. Many years ago while on the phone with an EarthX tech
trying to understand their prohibition against most smart chargers out
there in frustration I asked him if it was safe to charge their batteries
with my aircraft. Of course the answer was yes but a little further
discussion convinced me that it's not the battery they are trying to
protect, it's the BMS. Apparently their BMS can be damaged by the voltage
pulses sent by "desulfating" chargers. That seems to be not a concern from
your plot and the pictures which show that the "desulfating" mode is
selectable, not automatic.
I was specifically asking about this charger you have let us know about
because the description states *(lithium batteries are not charged)* which
makes me wonder if the "smart" part of the charger could end seeing some
behaviour of the lithium battery that it mistakes for a lead acid battery
problem, and shutting off.
Recently a client of mine replaced a $400+ EarthX because "it goes dead".
They dropped the offending one off and it was 0V. I left it hooked up to my
power supply overnight at 14.5V and then tested it. It came out at 96% of
new capacity (after 5 years, not bad). After checking the engine monitor
data and asking a few questions the best theory we can come up with is that
this perfectly good battery was replaced because they discharged it to BMS
shutoff a few times and their "smart" charger assumed a problem and
wouldn't charge it. So now they've spent $200 on a charger and have a spare
battery.
On Tue, Mar 14, 2023 at 12:58=AFPM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 12:24 PM 3/14/2023, you wrote:
>
> The NOCOs are way overpriced. Bob's example does a better job at 1/6th th
e
> price.
>
> Bob, have you found a similar charger for lithium batteries?
>
>
> There are lithium and then there are LITHIUM batteries.
> I've oft pondered the contradictions in performance
> claims by the various purveyors of lithium products.
>
> There are dozens of batteries that are simple
> assemblies of cells stacked 4-high proposed
> for service in a 14v system. They claim
> to be drop-in replacements for wet or SVLA
> products.
>
> Okay, if the thing is claimed to live happily
> in a lead-acid environment, then what's
> this "special lithium charger" stuff all about?
>
> Then there are products that offer battery
> management systems within the battery itself.
> The term "BMS" does not offer an industry
> wide description of form and function.
>
> Products that seek to assure consumers of
> 100% compatibility with the lead-acid world
> often include electronics adding substantially
> to the cost of the battery! Yet, there are as
> many (if not more) products offered with NO
> built in electronics. Some do offer a
> cell-balancing connector. Ebay and Amazon
> are replete with cell-balancing modules
> that cater to the DIY battery-array market.
>
> I'll call your attention to the figures here
> on my website:
>
> https://tinyurl.com/mw4fz3pf
>
> One figure illustrates a family of capacity
> vs. charge voltage plots for an A123
> LiFePO4 cell. Note the battery performance
> when charged at various termination voltages
> ranging from 3.3 to 3.7 volts. In a 4-stack
> array intended for 14v systems, these voltages
> correspond to system voltages of 13.2 to 14.8
> volts.
>
> Note that cell capacity is essentially maxed
> out with a charge voltage of 3.4 Volts/Cell
> (13.6V system) with no significant improvement
> above that.
>
> The other image is a snapshot of specs for
> a well known variety of LiFePO4 cells that
> state a max charging voltage of 4.2 until the
> current drops below 100mA. This would be a system
> voltage of 16.8 Volts!
>
> Perhaps this offers a reason for the success
> of the many bare-foot, 4-stack engine cranking
> products out there. As long as system voltage
> is greater than 13.6 (but less than 16.8),
> the battery has a high order probability of
> a useful life.
>
> So, what's all this lithium specific charger
> stuff about? The charger we've been discussing
> in this thread tops out at just under 15V. No
> red flags there.
>
> In the BMS camp for lithium products, we're
> told that the battery is a plug-n-play replacement
> of the EXISTING wet or SVLA battery. Rest assured
> that the BMS will protect your substantial investment
> from alternator malfeasance . . . except that its
> not clear to me that the legacy lead-acid system
> set up to charge and 14.2 to 14.8 volts is something
> to be worried about.
>
> So that's a long introduction to my response to
> your question. Unless someone has DATA to suggest
> otherwise, I'm of the not-so-humble opinion that
> lithium specific chargers are in the same class
> as battery desulfators. There are dozens of patents
> on desulfation processes NONE of which are accompanied
> by repeatable laboratory grade tests that demonstrate
> efficacy of their claims.
>
> I've got a EarthX battery on the bench that's
> be maintained by one of my venerable BatteryMinders
> for about 10 years. That reminds me, I think I'll
> run a new cap and load check on the little feller.
> Don't have an airplane to run it in but it's jump
> started a dozen or so vehicles over the years!
>
> The one thing I've not yet mentioned is the 'cell-
> balancing' feature suggested in some battery
> management philosophies.
>
> Cell balancing becomes a significant concern as
> the cells age. If the internal impedance and/or voltage
> vs. charge current one layer in the 4-stack array
> rises significantly over the others, it's capacity has
> been depressed. So while its brothers are still actively
> taking on more Joules of energy, the 'weak sister' is
> at risk for exacerbated damage due to over-charging.
> A cell balancing system places a dummy-load resistor
> across a compromised layer of cells to reduce the
> risks to the cells.
>
> Given what we've observed of the lithium art and
> science over the last decade, I'll suggest that cell
> balancing is probably not applicable to aircraft
> applications. Keep in mind that the majority market
> for batteries is populated with customers who routinely
> deep-discharge their batteries and flog 'em until they
> don't get up and hunt any more.
>
> We airplane guys are intently interested in
> CAPACITY of a battery compared against DESIGN
> GOALS for Plan-B endurance in battery only
> ops. The rule of thumb for battery replacement
> is to take it out of service at 80% of new
> or when battery-only endurance goals are not
> satisfied.
>
> In both SVLA and Lithium worlds, a battery is
> likely to still be cranking an engine when it's
> time to replace and before cell balancing becomes
> a significant issue.
>
> That's kind of a long winded answer to your
> question but hopefully gives you understanding
> that supports future decisions.
>
>
> Bob . . .
>
> ////
> (o o)
> ===========o00o=(_)=o00o======
==
> < Go ahead, make my day . . . >
> < show me where I'm wrong. >
> =======================
=========
>
> In the interest of creative evolution
> of the-best-we-know-how-to-do based
> on physics and good practice.
>
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