Today's Message Index:
----------------------
1. 06:41 AM - Re: How do I solder My son's x-mas present, the 'electricity board', Off topic, long and rambling with social commentary.. (Eric M. Jones)
2. 07:52 AM - Manual master switch (klehman@albedo.net)
3. 10:29 AM - Re: Manual master switch (Dan Branstrom)
4. 11:22 AM - Re: Manual master switch (Dave Morris)
5. 12:18 PM - Mounting OVM-14? (Condrey, Bob (US SSA))
6. 12:42 PM - Re: Mounting OVM-14? (Robert L. Nuckolls, III)
7. 02:24 PM - Re: Manual master switch (Rino Lacombe)
8. 08:37 PM - SD-8 Voltage Regulator Potential Overheating (Scott Diffenbaugh)
Message 1
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| Subject: | Re: How do I solder My son's x-mas present, the 'electricity |
board', Off topic, long and rambling with social commentary..
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>From: David A. Leonard (dleonar1@maine.rr.com) Sun Dec 28 - 7:45 PM
>Help!
>I have a toy for my 9 year old boy.. it's a kit, with a PCB, and a another
>PCB that solders to it. They both have tabs with silver contacts on them,
You can solder a hundred years and not discover the difference between 60%
tin-40% lead and 63% tin-37% lead solders. Most sources give the melting
points and that's that. But the real difference in tin-lead solders is far
more subtle: 60-40 solder has a small "mushy" temperature range. 63-37 goes
from solid to liquid with no mushy range at all (That's called eutectic).
The smaller the tin (first digit) the greater the mushy range. This is
important if there are gaps to bridge, and there always are.
When soldering sheetmetal or stained glass for example, you really want a
large range of mushy so you can stick a whole mess of solder onto the part
to fill gaps, so you might use 50-50, which has a liquid temperature of 461F
(maybe it's time for a propane torch) and a mushy range of 56F.
Why is 63-37 so common? It is shiny and pretty when it solidifies. This
makes assemblers proud. It is also great for solder plating PCBs for
example. The 60-40 solder solidifies like a wax--first the lead solidifies,
then a second later the tin solidifies. This leaves a hazy, frosted surface.
You can also remember:
1) Tin melts at a lower temperature than lead, improves wetability, costs
more, and is more flexible.
2) Lead melts at a much higher temperature, is poisonous, costs very little,
is stronger but easier to fatigue crack.
3) There is a great difference between solders of the same kind. Ersin is
very good, Alpha Metals has found its way into my junk box.
Dave--use 60-40.
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
Message 2
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| Subject: | Manual master switch |
--> AeroElectric-List message posted by: klehman@albedo.net
Gary you've brought some of my thoughts to the surface which is usually
dangerous. The pros of a manual switch seem to be no holding current and
a bit of security/theft protection if it is hidden or at least not on
the panel.
Well it turns out that the massive but low cost metal unit sold by
Summit racing (and even cheaper at my local farm supply) is actually
heavier than an electric contactor.
Flaming River make some that look to be composite and lighter. One sells
for around US$80. complete with an 18" remote handle extension. Another
version has a removeble plastic key. However it is easier to provide
security with a small switch or in other ways.
If I hard wire my battery to the starter, same as when my car engine was
in its first life, then it seems that there is no particular need for a
large contactor anyway. A small 40 amp relay (or even two for
redundancy) would suffice for killing power to the distribution system.
And even they won't kill battery bus power to my two efi and ignition
computers.
Anyway I'm having trouble justifying the need for a battery contactor or
manual switch. Seems it wouldn't really kill power to very much of my
aircraft for crash protection etc. and I'd need one for each of two
batteries. Then there is the starter contactor which doesn't seem to add
much protection either. There are a lot of car fires but the heavy
battery to starter wire doesn't seem to be a problem in those, near as I
can figure. Please correct me if someone believes otherwise. Bob has
mentioned in the archives that he prefers to use a starter contactor
even with automotive starters like mine. Fewer connectors and lower
resistance between the alternator, battery, and starter is attractive
though.
Ok this is already long (which I hate to do as it tends to discourage
comments) but I might as well mention my 40 amp ND internal voltage
regulator alternator and my 20 amp John Deere PM alternator. Both have
been fitted with large pulleys to slow them and help limit max current
output. Do I add two more contactors for over voltage protection?
Well I'll load the PM alternator with always on lights/strobes and
perhaps a fuel pump. Do I really care if it runs away and stuffs a few
extra amps into the battery till I can get on the ground? An old flooded
battery would warm up and vent some electrolyte and shrug it off. Not
sure about a small RG battery. I need to be informed about the regulator
failure but I'm not as convinced that I need an active OV protection
contactor here. It could be done with a small 40 amp relay or the one
B&C sells though.
The 40 amp ND alternator was chosen for both weight and so that a
regulator failure would not result in a hundred amps being available as
in the car. Of course any voltage spikes have to be lower too with a
small unit. OV protection is probably a good idea here though since I am
planning to use small batteries and the efi will only stand so much ov.
Since we are thinking out of the box a bit, what about a normally open
relay that adds say 30 amps of load to that alternator in the event of
an ov. Switch in an electric windshield defroster or car heater perhaps?
That would control the ov situation but still leave enough power
available to run my engine for an unlimited time without even bothering
to switch to my redundant efi system powered from the PM alternator. And
a relay failure would only disable the ov protection whereas an ov
contactor failure or activation would kill the alternator output. Such
an approach also avoids extra connectors in the wire between the
alternator and battery.
Seems I might still want one heavy duty crossfeed contactor for engine
starting if I use two small batteries but those batteries actually cost
more than one large and one small battery... Cost is secondary here
though. Or it looks like my PM alternator will probably run fine with a
large capacitor and ov protection instead of a small battery...
Ken
>
> In a message dated 12/28/03 8:28:47 AM Central Standard Time,
> glcasey@adelphia.net writes:
> What are the pros/cons of using a manual master (battery) switch instead of
> the tradition relay contactor? It looks to me like the advantage is that it
> eliminates a failure mode and reduces the wiring complexity.
> Good Morning Gary,
>
> Just as further food for thought, have you considered using a manual switch
> operated by a mechanical mechanism?
>snip
Message 3
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| Subject: | Re: Manual master switch |
--> AeroElectric-List message posted by: "Dan Branstrom" <danbranstrom@verizon.net>
(snip)Well I'll load the PM alternator with always on lights/strobes and
perhaps a fuel pump. Do I really care if it runs away and stuffs a few
extra amps into the battery till I can get on the ground? An old flooded
battery would warm up and vent some electrolyte and shrug it off.
I know that you've thought long and hard about what your choices are. They
aren't mine. To make the choices you're talking about, I would want the
following answers:
What is the exact voltage produced if regulators fail?
What is the time that the items turned on will tolerate that voltage?
What is the amount of heat generated over the time of the overvoltage?
Is the higher internal resistance of a flooded battery worth it?
How much does this shorten the life of your battery?
Where are the gasses vented during the overcharge? (It's my understanding
that both electrolyte and hydrogen would be given off).
Even though it may be minimal, what is the extra weight needed to protect
structures and terminals from corrosion, and do I want to inspect all the
wires close by for corrosion?
Where does the electrolyte go if the battery is cracked in an accident?
If the pullys are running slower, how much electricity is generated at low
engine RPM's?
I know that some car fires are caused by accidents that have forced battery
terminals on to metal, shorting the battery itself. (I've seen that one,
but flames didn't break out, but there was enough smoke to be scary. The
wrong sized battery contributed to that one, and the accident jammed the
hood closed, so it took some tools to get the hood open and disconnect the
battery).
To me, I'd rather trust an O.V. crowbar circuit, R.G. battery, and
contactor.
Dan Branstrom
Message 4
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| Subject: | Re: Manual master switch |
--> AeroElectric-List message posted by: Dave Morris <dave@davemorris.com>
At 10:31 AM 12/29/2003 -0800, Dan wrote:
>I know that some car fires are caused by accidents that have forced battery
>terminals on to metal, shorting the battery itself. (I've seen that one,
>but flames didn't break out, but there was enough smoke to be scary. The
>wrong sized battery contributed to that one, and the accident jammed the
>hood closed, so it took some tools to get the hood open and disconnect the
>battery).
My daughter lost her first car, a Honda Accord, to a battery that slipped
forward when she stopped and bumped a curb. The battery terminals
contacted the chassis and started a fire that she never noticed when she
got out of the car and walked away. The fire slowly engulfed the entire
compartment and "melted" the entire engine. Nobody noticed a thing hours
later, except that the hood looked a little darker than usual. The first
indication of a problem was when she got in again and tried to start the
car, and she couldn't push the clutch in because all the liquid had been
boiled out. No explosion, no raging blaze, no nothing. Just a completely
totalled vehicle.
Dave Morris
Message 5
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| Subject: | Mounting OVM-14? |
--> AeroElectric-List message posted by: "Condrey, Bob (US SSA)" <bob.condrey@baesystems.com>
I am collecting the parts to implement the ground power circuit that Bob recommends
but am at a bit of a loss about how the OVM-14 is mechanically mounted.
It doesn't appear that just putting ring terminals on the wires is sufficient
- would sticking it to the contactor with RTV do the trick? What have others
done?
Message 6
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| Subject: | Re: Mounting OVM-14? |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:17 PM 12/29/2003 -0800, you wrote:
>--> AeroElectric-List message posted by: "Condrey, Bob (US SSA)"
><bob.condrey@baesystems.com>
>
>I am collecting the parts to implement the ground power circuit that Bob
>recommends but am at a bit of a loss about how the OVM-14 is mechanically
>mounted. It doesn't appear that just putting ring terminals on the wires
>is sufficient - would sticking it to the contactor with RTV do the
>trick? What have others done?
That would work. Or use a large diameter (1")
piece of heatshrink to support it by one of the
fat wires coming to or leaving the contactor.
Bob . . .
Message 7
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| Subject: | Re: Manual master switch |
--> AeroElectric-List message posted by: "Rino Lacombe" <lacombr@nbnet.nb.ca>
> Anyway I'm having trouble justifying the need for a battery contactor or
> manual switch. Seems it wouldn't really kill power to very much of my
> aircraft for crash protection etc. and I'd need one for each of two
> batteries.
I use one and only one Master Switch (used on boats) in the ground circuit.
Theses switches are rated at 400 to 600 amps. Mine is from West Marine No.
335870
Then there is the starter contactor which doesn't seem to add
> much protection either. There are a lot of car fires but the heavy
> battery to starter wire doesn't seem to be a problem in those, near as I
> can figure. Please correct me if someone believes otherwise. Bob has
> mentioned in the archives that he prefers to use a starter contactor
> even with automotive starters like mine. Fewer connectors and lower
> resistance between the alternator, battery, and starter is attractive
> though.
>
> Ok this is already long (which I hate to do as it tends to discourage
> comments) but I might as well mention my 40 amp ND internal voltage
> regulator alternator and my 20 amp John Deere PM alternator. Both have
> been fitted with large pulleys to slow them and help limit max current
> output.
I think the larger pulleys do not limit max current, it only reduce rpm and
makes it easier on the alternator bearings.
> Seems I might still want one heavy duty crossfeed contactor for engine
> starting if I use two small batteries but those batteries actually cost
> more than one large and one small battery..
I have a small battery (17 AH) to start my engine, it is a Mazda rotary 13b
engine. That small battery is doing just fine. I use the second battery to
feed my electronics including the engine controller.
> Ken
>>
Message 8
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| Subject: | SD-8 Voltage Regulator Potential Overheating |
--> AeroElectric-List message posted by: "Scott Diffenbaugh" <diff@foothill.net>
Hi Bob & fellow Listers,
Reached the point where I felt comfortable with my total system design
utilizing Z-13 & was placing the order with Tim at B&C today when the topic
of loading the SD-8 came up. When I indicated I had designed it for 8 amps
or less continuous, Tim informed me the regulator was designed for 2 to 3
amps continuous and would most likely fry at 8 amps unless some sort of
cooling was provided. If located in the cockpit, it should have additional
heatsinking and a fan would be a good idea, but there could be electrical
noise. If mounted on the firewall in the engine compartment there would be
less noise, but it would need substantial heat sinking, and/or a blast tube.
In an earlier response, Bob mentioned if loaded greater than 8 amps
continuous, a heat sink was necessary, or possibly a more robust regulator
like the KeyWest. I Google searched KeyWest and only found one hit, where
someone experienced regulator failure due to overheating with a Rotax & it
also destroyed their alternator. Also was not able to find the KeyWest
website. Anyone have its URL?
Does anyone have experience running the SD-8 continuously at 8 amps? Unless
I have overlooked something, neither the installation instructions for the
SD-8 nor Z-13 mention heat sinks or blast tubes. Am I missing something or
might Z-13 users experience regulator overheating if their main alternators
fail? (according to Tim, the stuff inside the regulator housing starts to
ooze out when overheated)
Thank you in advance for your assistance with this issue. I have put my
order on hold until I have a better understanding.
Scott, RV7A
Scott Diffenbaugh
diff@foothill.net
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