Today's Message Index:
----------------------
1. 06:37 AM - Re: Re: Brownout Step Up Converter (Robert L. Nuckolls, III)
2. 09:25 AM - Difference between B&C Starter Contactors? (David Carter)
3. 09:59 AM - Re: Difference between B&C Starter Contactors? (user9253)
4. 10:21 AM - Re: Difference between B&C Starter Contactors? (Jeff Luckey)
5. 12:00 PM - Re: Difference between B&C Starter Contactors? (Robert L. Nuckolls, III)
6. 12:12 PM - Re: Difference between B&C Starter Contactors? (Robert L. Nuckolls, III)
7. 09:06 PM - Re: Re: Brownout Step Up Converter (Sebastien)
Message 1
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| Subject: | Re: Brownout Step Up Converter |
At 06:54 PM 9/15/2020, you wrote:
>
>How about using the DC-DC converter (no backup battery), but only energize
>it during engine start? A dual diode will allow either the DC-DC
>converter or the power bus to supply current to the EFIS. Wired that way,
>there is no concern about the DC-DC converter malfunctioning during flight.
>
>--------
>Joe Gores
Yup . . . see Z101
Bob . . .
Message 2
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| Subject: | Difference between B&C Starter Contactors? |
Anyone know if there is any practical difference between the S702-1 & the
S811-1, besides $10.00? I'm redoing the electrical system in my RV-7A (I'm
not the builder) per Z101, and want to replace the existing contactors,
which I believe are the ones Vans sells. The form factor on the B&C starter
contactors is different, which will make it slightly more complicated to
retrofit. Is it worth the effort?
Thanks,
David
---
David Carter
david@carter.net
Message 3
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| Subject: | Re: Difference between B&C Starter Contactors? |
The $10 might pay for the PMA.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498396#498396
Message 4
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| Subject: | Re: Difference between B&C Starter Contactors? |
Hi David,
It is my understanding that the S702-1 (sometimes called a "pancake" soleno
id) is a solenoid that has been optimized for cranking duty.=C2- I believ
e that Ford created the design some time in the 70s specifically to start e
ngines in Ford vehicles.=C2- Things like contact size and contact pressur
e were optimized for the specific task of short-duration high-current loads
encountered when starting engines.=C2- I believe that this makes the des
ign less likely to be a victim of the "weld shut" scenario that we occasion
ally hear about with older tin-can types.=C2- =C2-Based on this info I
have decided to use it in my RV-7 and in a friend's RV-14.
The other "tin can" configuration is a more general-purpose solenoid.=C2-
It seems to work fine as it is in thousands of little GA aircraft.
Some advantages of the S702-1:1. Optimized for the task of starting2. Ubiqu
itous - is in millions of Ford cars & trucks - you can get one at almost an
y auto parts store (even in PoDunk North Dakota)3. Cost effective
Jeff Luckey
On Thursday, September 17, 2020, 09:47:32 AM PDT, David Carter <david@c
arter.net> wrote:
Anyone know if there is any practical difference=C2-between the S702-1 &
the S811-1, besides $10.00?=C2- I'm redoing the electrical=C2-system i
n my RV-7A (I'm not the builder) per Z101, and want to replace the existing
contactors, which I believe=C2-are the ones Vans sells. The form factor
on the B&C starter contactors is different, which will make it slightly mor
e complicated to retrofit. Is it worth the effort?=C2-
Thanks,David
---
David Carter
david@carter.net
Message 5
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| Subject: | Re: Difference between B&C Starter Contactors? |
At 11:21 AM 9/17/2020, you wrote:
>Anyone know if there is any practical
>difference=C2 between the S702-1 & the S811-1,
>besides $10.00?=C2 I'm redoing the electrical=C2
>system in my RV-7A (I'm not the builder) per
>Z101, and want to replace the existing
>contactors, which I believe=C2 are the ones Vans
>sells. The form factor on the B&C starter
>contactors is different, which will make it
>slightly more complicated to retrofit. Is it worth the effort?=C2
Go here and get one of these
https://tinyurl.com/y5yzynuq
or get the same part from your
local Smiley Jack's Car Parts emporium:
Standard SS598T
Works good, lasts a long time.
Bob . . .
Message 6
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| Subject: | Re: Difference between B&C Starter Contactors? |
At 12:17 PM 9/17/2020, you wrote:
>Hi David,
>
>It is my understanding that the S702-1 (sometimes called a "pancake"
>solenoid) is a solenoid that has been optimized for cranking
>duty. I believe that Ford created the design some time in the 70s
>specifically to start engines in Ford vehicles. Things like contact
>size and contact pressure were optimized for the specific task of
>short-duration high-current loads encountered when starting
>engines. I believe that this makes the design less likely to be a
>victim of the "weld shut" scenario that we occasionally hear about
>with older tin-can types. Based on this info I have decided to use
>it in my RV-7 and in a friend's RV-14.
>
>The other "tin can" configuration is a more general-purpose
>solenoid. It seems to work fine as it is in thousands of little GA aircraft.
The all metal, contactors are available in an
intermittent duty style but they're hard to
find . . . and yes, they feature a large-area,
low-pressure contact not ideally suited to
hi-inrush loads. But they were used by the thousands
in all manner of vehicle including aircraft
for decades.
The more nimble footed, small-area, high-pressure
contact devices are more suited to this
application. They've become the gold-standard
for resistance to sticking . . . ESPECIALLY
with permanent magnet starters.
The Standard SS598T is but one example of dozens
in this class of device. Inexpensive and
very reliable in aircraft. Keep in mind that
aircraft engines get started what . . . maybe
50 times a year? My car gets started 50 times
a month!
Bob . . .
Message 7
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| Subject: | Re: Brownout Step Up Converter |
A couple weeks ago I ordered one of these off eBay:
https://www.ebay.ca/itm/192243452240
DC-DC Converter
5 Amps
Input 3-35 V
Output 5-40 V
I'm trying to support ~1 A EFIS during start so I thought 5 A would be
plenty but a closer look at the description says it's good for 3 A with a
maximum of 5 A. Turns out the 3 A is on the input side, not the output
side. With a voltage output set point of 10V and a ~1 A lamp connected, the
lamp browns out (literally) as soon as the input voltage sags below 9V. A
long way from the 7V minimum I was hoping for. I plugged it into a Battery
Analyzer at 1.0 and 0.5 A and momentarily dropped the input voltage to 8V.
Even when voltage is restored it takes several seconds to recover back to
the set voltage with a 1 A load. A 0.5 A load is fine.
[image: Brownout Booster.jpg]
So I think these things work fine but are undersized for the application.
Unfortunately as soon as I look for 10A or 15A ones the minimum input
voltage rises to 8.5 or even 10V. I'm ready to give up on this little
project unless someone has found a cheap step up converter that will output
at least 1 A @ 10 V with the bus voltage available during engine start.
On Thu, Sep 17, 2020 at 7:08 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 06:54 PM 9/15/2020, you wrote:
>
>
> How about using the DC-DC converter (no backup battery), but only energize
> it during engine start? A dual diode will allow either the DC-DC
> converter or the power bus to supply current to the EFIS. Wired that way,
> there is no concern about the DC-DC converter malfunctioning during flight.
>
> --------
> Joe Gores
>
>
> Yup . . . see Z101
>
>
> Bob . . .
>
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