Today's Message Index:
----------------------
1. 04:32 AM - Re: Starter Solenoid fuse blows, ideas? (Ralph Hoover)
2. 09:19 AM - Re: Starter Solenoid fuse blows, ideas? (Todd Heffley)
3. 10:01 AM - Re: Starter Solenoid fuse blows, ideas? (Terry Miles)
4. 10:28 AM - Re: Starter Solenoid fuse blows, ideas? (Robert L. Nuckolls, III)
5. 03:09 PM - Re: Mag and Lightspeed ignition grounding (Peter Sokolowski)
6. 03:23 PM - Circuit for automatic fuel pump engageing (Peter Sokolowski)
7. 10:04 PM - Re: Starter Solenoid fuse blows, ideas? (mdharfst@comcast.net)
Message 1
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| Subject: | Re: Starter Solenoid fuse blows, ideas? |
Mike,
When the fuse blows what does it look like? If the element looks like it
melted and sagged until it parted you have a consistent slight overload.
If it the element is vaporized and black it was a large overload. I
suspect that if it is blowing 10A fuses consistently but at long
intervals and it operates on a 3 amp fuse for long periods of time you
may have an intermittent fault to ground. The solenoid pull in current
should not change with the load on the solenoid. The current required to
pull the solenoid is greater than the hold current so I suspect that
voltage drop while cranking is not the problem. You mentioned that you
do not know when the fuse blows. Does the starter drop out while
engaged? Does the solenoid start to move, click and drop out? Is it just
dead while no problem was noted on the previous start? Do you have a
snubber diode across the solenoid coil?
--
Ralph C. Hoover
RV7A
hooverra at verizon dot net
mdharfst@comcast.net wrote:
>
> I have had a small nagging problem for several years since I started flying my
plane. All my attempts to mitigate the problem have not solved it but have decreased
the frequency. The basic problem is that the fuse that controls the firewall
mounted starter solenoid occasionally blows. Since the fuse is under the
glareshield it is a pain to change. Basically I am looking for ideas of what
might be causing this to happen and how to test to see if that idea is the
cause.
> (snip)
> Im open for suggestions.
> Mike Harfst
>
>
>
Message 2
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| Subject: | Re: Starter Solenoid fuse blows, ideas? |
Ron
I had a similar experience on a C-195. Turned out to be Chaffing at
the firewall feed-though, Chaffing ONLY occurred when the engine was
running!
Cast a ctitical eye on all of the wire-routing....
Good Luck
Todd
Message 3
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| Subject: | Starter Solenoid fuse blows, ideas? |
Mike,
I am only a Saturday afternoon mechanic. Take the following as "off the top
of my head" ideas.
Unless I missed it, you didn't mention about the coil on the starter motor.
Without looking at your system, it is likely your B&C "starter solenoid"
actually uses about 1 amp max to energize another coil that is bolted to the
starter motor. I'll call that second coil C-2 so we are both sure which
component we are talking about. C-2's job like any coil is to close the big
juice contactors so current at 150 amps maybe can go from the batt to the
starter motor. C2 is also responsible to throw the pinion gear into the fly
wheel and keep it that way until you let off on the starter button. C-1's
job is to energize C-2. The fuse that blows feels the draw from both C-1 and
C-2.
Your comment about having to move the prop or it blows a 2nd fuse makes me
want to investigate C-2 the coil on the skytec. Skytec will sell you
another coil for about $5 if they don't just out and out give you one from
stock. http://www.skytecair.com/ They are real good about answering tech
questions there too. If you call have model and serial # ready.
The C-2 casing is held on the starter motor with a couple of screws and the
guts can get swapped out just as easy. Look around at your ring gear and
the starter gears and see if you see any scoring. The pinion doesn't thrust
into the gears, or has some other mechanical problem the mech load creates
an amp draw that can eat a fuse--and be a literal roulette wheel like
problem that only happens some of the time.
Hope this leads you to a couple of ideas more. Good luck
Terry Miles
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
mdharfst@comcast.net
Sent: Saturday, July 07, 2007 6:36 PM
Subject: AeroElectric-List: Starter Solenoid fuse blows, ideas?
I have had a small nagging problem for several years since I started flying
my plane. All my attempts to mitigate the problem have not solved it but
have decreased the frequency. The basic problem is that the fuse that
controls the firewall mounted starter solenoid occasionally blows. Since the
fuse is under the glareshield it is a pain to change. Basically I am
looking for ideas of what might be causing this to happen and how to test to
see if that idea is the cause.
This is a detailed description of my system. An O-320 engine with a Skytec
lightweight starter, two Slick mags, B&C 40A alternator and B&C voltage
regulator, a 17AH RG battery and master solenoid (S701-1) on the aft side of
the firewall, a B&C starter solenoid (S702-1) on the forward side of the
firewall, and a fuseblock under the glareshield. The big cables are #4
welding cable. The battery is 12" from the master solenoid. The master to
starter solenoid cable is about 10" through the firewall.
The plane is wired based on Bob's Z-11 drawing with the starter solenoid
circuit set up like Z-22. I use the rotary keyed mag/starter switch from
ASSC.
Here is a description of the exact problem.
I have a fused wire leading to the bat terminal of the keyed switch that
activates the firewall mounted starter solenoid. The fuse is a 7.5A fuse.
Occasionally the fuse blows during starter cranking and then has to be
replaced. The first few times I replaced the fuse with another 7.5A fuse.
The fuse would blow every couple of months, and might occur two or three
times in a row when it happened. Also, it is tough to know exactly when the
fuse blows. If it happens after the solenoid engages I might get it started
but won't realize it is blown until I try to start it again for the return
trip or maybe days later for the next trip. That makes it difficult to pin
down associated factors.
Here are a few things I've tried.
Originally I figured the starter itself was sticking and causing the starter
solenoid to overload so I put in a 10A fuse. This lowered the frequency of
occurrence, to about once or twice a year, but did not totally eliminate it.
I originally used the small light duty solenoid from B&C (the S704-1) which
I thought might not be up to the task. I eventually swapped it out for a
heavy duty intermittent duty solenoid and increased the size of the
associated wiring to be sure the wire size didn't cause a problem or have an
intermittent fault to ground somewhere. When I changed the solenoid the
frequency went down to about once a year.
Recently this 10A fuse blew and I replaced it with a 15A fuse that I had
with me but it immediately blew also when I turned the key. So I hand
propped the plane and took it to the hangar. The next day when I checked it
the plane had no problem and started right up with a new fuse. Just to check
the normal current flowing through this circuit with the plane acting well,
I started it with successively smaller fuses until one finally blew when I
turned the key. The plane started fine with a 15A fuse, with a 10A, with a
7.5A, with a 4A, with a 3A and finally with a 1A fuse the starter kicked in
and started the plane but the 1A fuse blew. This told me that the solenoid
normally drew between 1 and 3 amps, just like it is supposed to, when the
system is acting normally. It also told me that when the system blows the
fuse, the current draw can be as high as 15A momentarily. That just doesn't
make sense, how can a little solenoid pull 15A?
Here are a few ideas that I haven't been able to confirm, but I think might
be true.
If I don't move the prop, after a fuse blows, the next fuse will blow too,
probably.
A blown fuse is a little more likely to happen when the engine is hot, but
not always.
It happens easier if I have to crank the starter for quite awhile, I can't
tell when exactly it pops though.
Early on I checked the voltage at the switch during cranking and it will
drop to 10V before too much cranking. I haven't checked it for a couple of
years. I am on my second battery too.
Also, the possibility exists that the keyed switch is the culprit, but I
won't replace it to test that idea. I would rather rewire to two toggle
switches and a starter button. I'm saving that action for later.
I'm open for suggestions.
Mike Harfst
Message 4
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| Subject: | Re: Starter Solenoid fuse blows, ideas? |
At 10:35 PM 7/7/2007 +0000, you wrote:
>
>I have had a small nagging problem for several years since I started
>flying my plane. All my attempts to mitigate the problem have not solved
>it but have decreased the frequency. The basic problem is that the fuse
>that controls the firewall mounted starter solenoid occasionally blows.
>Since the fuse is under the glareshield it is a pain to change. Basically
>I am looking for ideas of what might be causing this to happen and how to
>test to see if that idea is the cause.
>
>This is a detailed description of my system. An O-320 engine with a Skytec
>lightweight starter, two Slick mags, B&C 40A alternator and B&C voltage
>regulator, a 17AH RG battery and master solenoid (S701-1) on the aft side
>of the firewall, a B&C starter solenoid (S702-1) on the forward side of
>the firewall, and a fuseblock under the glareshield. The big cables are #4
>welding cable. The battery is 12" from the master solenoid. The master to
>starter solenoid cable is about 10" through the firewall.
>The plane is wired based on Bob's Z-11 drawing with the starter solenoid
>circuit set up like Z-22. I use the rotary keyed mag/starter switch from
>ASSC.
Z-22 describes a boost relay for the purpose of
utilizing the starter's built in solenoid while
isolating the relatively fragile starter push button
or key-switch from the ravages of starter solenoid
inrush currents. See:
http://aeroelectric.com/articles/strtctr.pdf
>Here is a description of the exact problem.
>I have a fused wire leading to the bat terminal of the keyed switch that
>activates the firewall mounted starter solenoid. The fuse is a 7.5A fuse.
>Occasionally the fuse blows during starter cranking and then has to be
>replaced. The first few times I replaced the fuse with another 7.5A fuse.
>The fuse would blow every couple of months, and might occur two or three
>times in a row when it happened. Also, it is tough to know exactly when
>the fuse blows. If it happens after the solenoid engages I might get it
>started but won't realize it is blown until I try to start it again for
>the return trip or maybe days later for the next trip. That makes it
>difficult to pin down associated factors.
Starter solenoid? If you have a boost relay installed, the the
firewall mounted contactor goes away.
>Here are a few things I've tried.
>Originally I figured the starter itself was sticking and causing the
>starter solenoid to overload so I put in a 10A fuse. This lowered the
>frequency of occurrence, to about once or twice a year, but did not
>totally eliminate it.
The "STARTER" fuse on the main bus powers only the coil
of what ever device is expected to operate when the start
contacts are closed. If you're using an S702-1 style Starter
Contactor
http://www.aeroelectric.com/Pictures/Contactors/s702-1l.jpg
then the current draw through this fuse is limited to about
5A max and a 7.5a fuse will handle this task indefinitely.
>I originally used the small light duty solenoid from B&C (the S704-1)
>which I thought might not be up to the task. I eventually swapped it out
>for a heavy duty intermittent duty solenoid and increased the size of the
>associated wiring to be sure the wire size didn't cause a problem or have
>an intermittent fault to ground somewhere. When I changed the solenoid
>the frequency went down to about once a year.
Now I'm really lost. The S704-1 is a 30A plastic
relay suggested as a stand-in for panel mounted
switches that do not do well controlling the starter
contactor/solenoid assembly directly -OR- for the
prevention of Starter Engagement Run-on phenomenon
common to PM motor starters. See notes on Figure Z-22
on page Z-5 of
http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf
>Recently this 10A fuse blew and I replaced it with a 15A fuse that I had
>with me but it immediately blew also when I turned the key. So I hand
>propped the plane and took it to the hangar. The next day when I checked
>it the plane had no problem and started right up with a new fuse. Just to
>check the normal current flowing through this circuit with the plane
>acting well, I started it with successively smaller fuses until one
>finally blew when I turned the key. The plane started fine with a 15A
>fuse, with a 10A, with a 7.5A, with a 4A, with a 3A and finally with a 1A
>fuse the starter kicked in and started the plane but the 1A fuse blew.
>This told me that the solenoid normally drew between 1 and 3 amps, just
>like it is supposed to, when the system is acting normally. It also told
>me that when the system blows the fuse, the current draw can be as high as
>15A momentarily. That just doesn't make sense, how can a little solenoid
>pull 15A?
We're wrapped about some semantic axles here. The S704-1
is a power relay, the S702-1 is a starter contactor (BIG
relay) and a solenoid is that hunk of stuff bolted to the
side of your starter that pushes the pinion gear out to
engage the ring gear. Further, the back end of the solenoid
is fitted with a contactor that closes power to the starter
motor only after pinion gear engagement is achieved.
If your starter switch contacts on the key-switch are driving
an S704-1 relay, then this coil needs just over 100 milliamps
of operating current. Your experiment with the 1A fuse confirms
this. If you're blowing fuses, then some transient fault condition
exists in either the wiring between starter switch and boost
relay or within the starter switch itself. Instant blowing
of the 15A fuse you cited is a good confirmation of this.
Your STARTER fuse should function well with 1A driving a
piece of 22AWG wire that runs through the BAT terminal of
your keyswitch to the starter boost relay illustrated in
Figure Z-22.
I'm mystified about the "firewall mounted" starter
solenoid . . . are you speaking about the S704-1
relay here? If, when you installed the S704-1 relay
you eliminated a firewall mounted contactor as Z-22
suggests, then we can zero in on the transient fault
that is taking the STARTER fuse to ground and causing
it to open.
>Here are a few ideas that I haven't been able to confirm, but I think
>might be true.
>If I don't move the prop, after a fuse blows, the next fuse will blow too,
>probably.
>A blown fuse is a little more likely to happen when the engine is hot, but
>not always.
>It happens easier if I have to crank the starter for quite awhile, I can't
>tell when exactly it pops though.
>
>Early on I checked the voltage at the switch during cranking and it will
>drop to 10V before too much cranking. I haven't checked it for a couple of
>years. I am on my second battery too.
>
>Also, the possibility exists that the keyed switch is the culprit, but I
>won't replace it to test that idea. I would rather rewire to two toggle
>switches and a starter button. I'm saving that action for later.
It does suggest an experiment. Wire in a temporary
push button of any size with a new 22AWG wire from the
fuse block through the push button and out to the S704-1
relay. Use a 5A or less fuse in the fuseblock. See how
this runs for awhile. If the fuseblowing event goes away,
all this leaves is the keyswitch and wires downstream of
the keyswitch that you've eliminated by the experiment.
Bob . . .
Message 5
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| Subject: | Re: Mag and Lightspeed ignition grounding |
Hello all,
I am wiring my panel and actually the ignition switch, contacting the mag
and the Lightspeed to the latter.
My question is the following: As to my best knowledge the shield from the
Mag wire should not be contacted with ground at the switch, the shield from
the Lightspeed cable will be contacted to ground at the switch. Is this
working (long term), as the Mag will be shortened with the ground from the
Lightspeed ?
Or may I contact the ground from the mag together with the ground from the
Lightspeed (ground loop !) ?
Thanks for your help
Peter Lancair 360 (85%)
Message 6
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| Subject: | Circuit for automatic fuel pump engageing |
Hello all,
I am looking for some hints / circuits for automatic switching of my fuel
transfer pumps. As it is standard with the Lancair 360, I have two wing
tanks and a header tank. As I do not want to switch on the transfer pumps
manually every 30 minutes, probably forgetting it at all, I want to build in
an "intelligent" circuit doing it for me.
My set up is, that I have a capacitive level sensor in the header tank,
providing 0 to 5 Volt depending on the fuel level. In addition, I have an
independent sensor at about 15 gallons which will give me a last warning in
case the circuit or transfer pumps isnot working.
Does someone already went through this experiment and is willing to share
his wiring drawings with me ? Even it is possible to develop something like
that by my one, one does not have to re-invent the wheel.
Thanks in advance,
Peter Lancair 360 (85%)
Message 7
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| Subject: | Re: Starter Solenoid fuse blows, ideas? |
Thanks for the responses.
Ralph wrote:
>>When the fuse blows what does it look like? vaporized and black?<<<
The blown fuses are vaporized, like a overload would cause. I do have all the diodes
installed in the circuit.
Todd wrote:
>>>Chaffing at the firewall feed-though, Chaffing ONLY occurred when the engine
was running!<<
Hmmmm, that could be a source of an intermittent fault. I dont have a fat wire
going through the FW. It is a custom made, through connection. I will go over
all the other wiring again though just to make sure.
Terry
Yes, the solenoid from Skytec on the starter motor itself could be the problem.
I may have to swap it out. I did a solenoid replacement early on with a rebuilt
solenoid when I accidentally stripped a copper bolt on the original. Skytec
may have given me a slightly faulty replacement part. Ill put this on the list.
Bob N
I am sorry for any confusion, maybe some of my terminology is not exact.
I originally wired my plane based on Z-11 (an earlier version/number really) with
the starter circuit based on the original Z-22. I used an S704 relay mounted
on the front of the firewall. When that relay failed after 160 hrs I went over
the schematic carefully. I think I understand the schematic, in fact Im the
guy that had several off-list emails with you that resulted in the revised Z-22
drawing published in June 05 with all the right diodes in the right places.
Anybody can pull up the archives from June 05 to read the discussions in greater
detail.
In those emails I proposed using a heavier duty contactor/relay/solenoid to replace
the S704. Your response was: You COULD replace the S704 with a HEAVIER duty
still device like a starter contactor, but it's not necessary. Try the NEW
Z-22 and see what it does for you. Since I live close to Vans I already had their
starter relay version by the time you replied so I went ahead and used it.
In their catalog this is referred to as a Starter Solenoid, intermittent duty
relay for the starter motor and in my installation it is on the firewall. I am
not referring to the big honking monster that is on the Skytec starter motor.
Again, I apologize for any terminology confusion.
I like the idea of jumping around the keyswitch with a starter button to test the
keyswitch. Unfortunately with a frequency of once or twice a year it will take
a long time to know for sure. I know your feeling about keyswitches and Im
beginning to feel the same way. Maybe what I need to do is come over from the
dark side and rewire to a couple of toggles and a pushbutton. That will probably
be a winter project. What I am doing in the short term is to put a 30A fuse
in the fuse block position and wire a 15A CB in series with the fuse. Now I
can see when the CB blows and just reset it. In a month or so Ill replace the
15A CB with a 5A CB and see what happens.
There are some good suggestions here, thanks everyone. Any others to add to the
list?
Mike Harfst
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