Today's Message Index:
----------------------
1. 06:41 AM - Re: Switch ratings? (user9253)
2. 07:51 AM - Re: Switch ratings? (Charlie England)
3. 09:58 AM - Re: Switch ratings? (user9253)
4. 10:33 AM - Re: Switch ratings? (Charlie England)
5. 10:46 AM - Re: Switch ratings? (David Saylor)
6. 11:05 AM - Re: Questions as I Design My Circuit Diagram (markfw)
7. 11:52 AM - Re: ATO vs ATC fuses (Robert L. Nuckolls, III)
8. 11:53 AM - Re: ATO vs ATC fuses (Robert L. Nuckolls, III)
9. 11:54 AM - Re: Switch ratings? (Robert L. Nuckolls, III)
10. 01:46 PM - Re: Desulfators and Lithium (Kelly McMullen)
11. 02:51 PM - Re: Desulfators and Lithium (skywagon185guy .)
12. 07:34 PM - Re: Switch ratings? (Robert L. Nuckolls, III)
13. 08:38 PM - Re: Alternator stops working at low idle RPM (Argonaut36)
Message 1
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| Subject: | Re: Switch ratings? |
A conservative rule of thumb is that the 14 volt DC rating is equal to the 120
volt AC rating. I would feel comfortable switching up to 20 amps with this
switch. Above that, consider using a relay. A switch that carries more than
its rated current is not going to immediately self destruct. But its life will
be
reduced. Instead of 100,000 operations, its life may be reduced to 50,000
operations. Even so, the switch could outlive the airplane.
If switching an inductive load, install an arc suppression diode across the
inductor coil to reduce sparking across the switch contacts.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=493818#493818
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| Subject: | Re: Switch ratings? |
On 12/13/2019 11:19 PM, David Saylor wrote:
> Are switchratings related to power? I'm wondering if I can assume
> that a 12A/28VDC rating would be equivalent to a 24A/12VDC rating.
> TheswitchI'm interested in is rated at 125VAC and 28VDC but not
> 14V. Is 24A a safe assumption at 14V? Or is there more to it? This
> is the switch: https://www.mcmaster.com/7337k98
>
> --Dave
I wouldn't consider doing that. Switches have to deal with both arcing
(make/break) and the heat created by the current flowing through the
components of the switch. Loading the switch with twice the rated
current sounds like serious abuse to me.
Charlie
Message 3
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| Subject: | Re: Switch ratings? |
There is a typo above and the switch is actually rated for 15 amps at 28 volts
DC.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=493820#493820
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| Subject: | Re: Switch ratings? |
On 12/13/2019 11:19 PM, David Saylor wrote:
> Are switchratings related to power? I'm wondering if I can assume
> that a 12A/28VDC rating would be equivalent to a 24A/12VDC rating.
> TheswitchI'm interested in is rated at 125VAC and 28VDC but not
> 14V. Is 24A a safe assumption at 14V? Or is there more to it? This
> is the switch: https://www.mcmaster.com/7337k98
>
> --Dave
If you can live without the locking feature, here are a few 25A
possibilities
https://www.newark.com/w/c/switches-relays/switches/toggle-switches?switch-operation=on-on&contact-configuration=dpdt&contact-current-max=25a
Message 5
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| Subject: | Re: Switch ratings? |
Thank you Charlie and Joe. Good advice. Looks like I'm going switch
shopping!
On Sat, Dec 14, 2019 at 10:39 AM Charlie England <ceengland7@gmail.com>
wrote:
> ceengland7@gmail.com>
>
> On 12/13/2019 11:19 PM, David Saylor wrote:
> > Are switch ratings related to power? I'm wondering if I can assume
> > that a 12A/28VDC rating would be equivalent to a 24A/12VDC rating.
> > The switch I'm interested in is rated at 125VAC and 28VDC but not
> > 14V. Is 24A a safe assumption at 14V? Or is there more to it? This
> > is the switch: https://www.mcmaster.com/7337k98
> >
> > --Dave
> If you can live without the locking feature, here are a few 25A
> possibilities
>
> https://www.newark.com/w/c/switches-relays/switches/toggle-switches?switch-operation=on-on&contact-configuration=dpdt&contact-current-max=25a
>
>
Message 6
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| Subject: | Re: Questions as I Design My Circuit Diagram |
Bob,
Thank you for your reply.
I changed Z11 in four ways:
1. I am using an EFI system so I enlarged the Endurance Bus to incorporate all
of the EFI component circuits;
2. I added a Lighting Bus with C/B's just to make wiring the panel easier and because
I was out of fuse positions on my Port side fuse block;
3. I did not incorporate the E-Bus alternate feed;
4. I used SSR relays rather than contactors.
I assumed that Z11 was correct. I was only asking about the reasoning about when
to use fuses for my own education.
Does 8AWG wire qualify as "fat" in this context of circuit protection?
I will have an O-340 from LyCon as my engine.
My load analysis is attached to this e-mail.
Joe, I was not asking about a second battery to backup my primary battery. I was
asking about it as a way to extend my flight time in the Alternator Out situation.
With my EFI my ALT OUT cruise power consumption is 20A so a 7 pound ETX1200
battery would give me approximately an hour of flight time, which should
work for most of my needs. I was just exploring what it would take to add in a
second battery for certain higher risk trips over water or mountains so I would
not have to carry that extra weight all of the time.
Mark
P.S. Is there any way to respond to replies to an original post individually rather
than as a group?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=493823#493823
Attachments:
http://forums.matronics.com//files/current_electric_loads__v5_214.xlsx
Message 7
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| Subject: | Re: ATO vs ATC fuses |
At 07:56 PM 12/13/2019, you wrote:
>Is there a preference for our OBAM aircraft between ATO (housing
>open at the bottom) and ATC (closed housing) fuses? I can imagine
>that when a fuse blows some particles of metal might get spewed out
>of an open housing, but I have no idea if this is the case.
Either is suited to our purposes.
Bob . . .
Message 8
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| Subject: | Re: ATO vs ATC fuses |
At 08:07 PM 12/13/2019, you wrote:
>Interesting question. At the same time I'd like to ask if there is
>any downside to using mini fuses.
Not aware of any pre-fabricated panels
for the mini fuses. You're looking for ease
of installation and robustness. The fuseblocks
eliminate breaker panels and bus bars while
allowing the distribution to be mounted out
of sight/mind.
Any 'savings' for down-sizing to mini fuses
would be small.
Bob . . .
Message 9
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| Subject: | Re: Switch ratings? |
At 11:19 PM 12/13/2019, you wrote:
>Are switch=C2 ratings related to power?=C2 I'm
>wondering if I can assume that a 12A/28VDC
>rating would be equivalent to a 24A/12VDC
>rating.=C2 The=C2 switch=C2 I'm interested in is
>rated at 125VAC and 28VDC but not 14V.=C2 Is 24A
>a safe assumption at 14V?=C2 Or is there more to
>it?=C2 This is the switch:=C2
>=C2 <https://www.mcmaster.com/7337k98>https://www.mcmaster.com/7337k98
>
>--Dave
That switch is fine for about anything you want to
do in the airplane . . . but why this one? It's
rather expensive
Bob . . .
Message 10
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| Subject: | Re: Desulfators and Lithium |
I just had pointed out to me a study that lends something to the discussion:
https://www.researchgate.net/publication/318890311_Impact_of_Pulse_Voltage_as_Desulfator_to_Improve_Automotive_Lead_Acid_Battery_Capacity
I can't say that it appears definitive, nor particularly quantitative,
but at least attempted to study the subject.
On 10/22/2019 8:45 AM, Robert L. Nuckolls, III wrote:
> At 01:33 AM 10/21/2019, you wrote:
>> *I too have read many articles that both applaud and disprove the
>> desulfurization theory. What I more or less believe is the results
>> that many tell about where they get 6 or 7 years from batteries well
>> maintained with with BATTERY MINDER maintainers.*
>
> Yup, been using the wall-wart BM and BT maintainers
> for decades enjoying very good service lives on
> a constellation of laboratory/test batteries.
> But those were batteries that lived in a house
> and were called upon perhaps a dozen hours/year
> or to jump start a vehicle.
>
>> *In my 50 years of dealing with batteries, I get about 3 or 4 years
>> from flooded batteries and sealed
>> batteries, but I have gotten 5 to 6 with the BATTERY MINDERS.*
>
Message 11
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| Subject: | Re: Desulfators and Lithium |
Battery Minders (maintainers)
I too am a big fan of using a Maintainer on any type of lead acid battery.
Been using them for years also with very good results EXCEPT for one
problem...
The Maintainer itself uses standard wall ac power, however, there is a
feedback that uses dc associated with the battery. The problem comes when
the main power stops, i.e. GFI controlled ac gets triggered off, main ac
power is cut, etc.
If this condition is not caught early enough, by disconnecting the
Maintainer, it will slowly discharge the battery until it is flat and quite
possibly damaged.
Maintainers are rarely checked once clipped on the battery as they are
dependable, except when primary ac power is dropped. I suggest to never
power the maintainer via a GFI controlled ac power plug as they are usually
on community circuits and subject to mysterious tripping. If no one is
present to notice and reset the fault, one will not be happy with the
results.....
On Sat, Dec 14, 2019 at 1:52 PM Kelly McMullen <kellym@aviating.com> wrote:
> kellym@aviating.com>
>
> I just had pointed out to me a study that lends something to the
> discussion:
>
> https://www.researchgate.net/publication/318890311_Impact_of_Pulse_Voltag
e_as_Desulfator_to_Improve_Automotive_Lead_Acid_Battery_Capacity
>
> I can't say that it appears definitive, nor particularly quantitative,
> but at least attempted to study the subject.
>
> On 10/22/2019 8:45 AM, Robert L. Nuckolls, III wrote:
> > At 01:33 AM 10/21/2019, you wrote:
> >> *I too have read many articles that both applaud and disprove the
> >> desulfurization theory. What I =9Cmore or less=9D believe
is the results
> >> that many tell about where they get 6 or 7 years from batteries well
> >> maintained with with BATTERY MINDER maintainers.*
> >
> > Yup, been using the wall-wart BM and BT maintainers
> > for decades enjoying very good service lives on
> > a constellation of laboratory/test batteries.
> > But those were batteries that lived in a house
> > and were called upon perhaps a dozen hours/year
> > or to jump start a vehicle.
> >
> >> *In my 50 years of dealing with batteries, I get about 3 or 4 years
> >> from flooded batteries and sealed
> >> batteries, but I have gotten 5 to 6 with the BATTERY MINDERS.*
> >
===========
===========
===========
===========
===========
===========
>
>
Message 12
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| Subject: | Re: Switch ratings? |
At 11:19 PM 12/13/2019, you wrote:
>Are switch=C2 ratings related to power?=C2 I'm
>wondering if I can assume that a 12A/28VDC
>rating would be equivalent to a 24A/12VDC
>rating.=C2 The=C2 switch=C2 I'm interested in is
>rated at 125VAC and 28VDC but not 14V.=C2 Is 24A
>a safe assumption at 14V?=C2 Or is there more to
>it?=C2 This is the switch:=C2
>=C2 <https://www.mcmaster.com/7337k98>https://www.mcmaster.com/7337k98
>
>--Dave
That switch is fine for about anything you want to
do in the airplane . . . but why this one? It's
rather expensive
Bob . . .
Message 13
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| Subject: | Re: Alternator stops working at low idle RPM |
Today the alternator went offline again after landing, despite a raised idle and
I was not able to reset it. I turned the engine off and I re-started it after
a few minutes. The alternator did not come online. So heat seems to be causing
the voltage regulator to cut off. My regulator is a VR371S. The S at the
end means sealed and, because it is sealed, it can be installed in the engine
compartment on the firewall. As pointed out by echristley, mine does not seem
to tolerate heat well.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=493831#493831
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