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todehnal
Joined: 06 Sep 2015
Posts: 2
Location: Kentucky Lake Area, KY
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 Posted: Wed Sep 09, 2015 4:01 am Post subject: Engine Starter Stalling |
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Hi Guys, New kid on the block, and I am looking for some advice. I have been having starter stall on cold starts. It will stop the prop a couple of times, and then spin up and start fine. I have been chasing this for a couple of months now. By the way, this is a Rotax powered RV-12. I know that when this happens the starter solenoid chatters. I can hear it. This chatter is caused by another starter circuit interrupt on the RV-12 called the spar pin relay. This safety device ensures that the removable wings spar pins are fully engaged, then completed the circuit to the start relay. I am now analyzing the battery. I downloaded data from the Dynon skyview, searched the spreadsheet and came up with a chart that shows the battery voltage during a typical start. If someone could take a look at the link below and offer some thoughts about the battery performance, or offer other advice, I would greatly appreciate it. Neat chart, and you can see the compression cycles on the chart. Thanks.........Tom
http://i296.photobucket.com/albums/mm182/tomscub/img002_zpsujxtzrle.jpg
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_________________
RV-12 with Skyview Panel built EAB by my wife & I.
First Flight: 11/21/13. It's a keeper....Tom |
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ceengland7(at)gmail.com
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| Posted: Wed Sep 09, 2015 4:46 am Post subject: Engine Starter Stalling |
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On Wed, Sep 9, 2015 at 7:01 AM, todehnal <tomscub(at)gmail.com (tomscub(at)gmail.com)> wrote:
| Quote: | --> AeroElectric-List message posted by: "todehnal" <tomscub(at)gmail.com (tomscub(at)gmail.com)>
Hi Guys, New kid on the block, and I am looking for some advice. I have been having starter stall on cold starts. It will stop the prop a couple of times, and then spin up and start fine. I have been chasing this for a couple of months now. By the way, this is a Rotax powered RV-12. I know that when this happens the starter solenoid chatters. I can hear it. This chatter is caused by another starter circuit interrupt on the RV-12 called the spar pin relay. This safety device ensures that the removable wings spar pins are fully engaged, then completed the circuit to the start relay. I am now analyzing the battery. I downloaded data from the Dynon skyview, searched the spreadsheet and came up with a chart that shows the battery voltage during a typical start. If someone could take a look at the link below and offer some thoughts about the battery performance, or offer other advice, I would greatly appreciate it. Neat chart, and you can see the compression cycles on!
the chart. Thanks.........Tom
http://i296.photobucket.com/albums/mm182/tomscub/img002_zpsujxtzrle.jpg
--------
RV-12 with Skyview Panel built EAB by my wife & I.
First Flight: 11/21/13. It's a keeper....Tom
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Where does the Dynon measure battery voltage? If it's measuring the voltage between its own B+ & ground terminals, it can't tell the difference between a weak battery and bad connections somewhere in the power circuit. They can be anywhere along the B+ path, or anywhere along the ground path back to the battery.
Try monitoring the battery voltage with a separate meter connected directly to the battery terminals (the posts, not the cable terminals on the battery terminals). Watch the meter while cranking the engine, & see how far voltage drops. It's hard to get the time domain resolution on a digital meter that you see on the Dynon graph, so you might try pulling the Dynon fuse, & power the Dynon with a wire directly to the battery B+ terminal so it can see true battery voltage during cranking. Remember to run a ground wire from the Dynon directly to the battery ground terminal also, if you try this.
If you see your voltage drops going to ~9-10volts instead of 6-8volts, then you probably have some bad connections somewhere in the circuit. If the battery is truly dropping to 6volts during cranking, then it's either not fully charged, or defective. (Or you've got a bad starter.)
[quote][b]
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Wed Sep 09, 2015 6:31 am Post subject: Engine Starter Stalling |
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The Dynon system allows the builder to place the voltage sensing lead
where ever he/she chooses. Could be where battery plus connects to the
bus, could be most anywhere. I don't know where the RV-12 plans call for
the connection, but with this aircraft built under EAB rules rather than
ELSA, he didn't have to follow the plans.
On 9/9/2015 5:44 AM, Charlie England wrote:
| Quote: |
On Wed, Sep 9, 2015 at 7:01 AM, todehnal <tomscub(at)gmail.com
<mailto:tomscub(at)gmail.com>> wrote:
<tomscub(at)gmail.com <mailto:tomscub(at)gmail.com>>
Where does the Dynon measure battery voltage? If it's measuring the
voltage between its own B+ & ground terminals, it can't tell the
difference between a weak battery and bad connections somewhere in the
power circuit. They can be anywhere along the B+ path, or anywhere
along the ground path back to the battery.
Try monitoring the battery voltage with a separate meter connected
directly to the battery terminals (the posts, not the cable terminals
on the battery terminals). Watch the meter while cranking the engine,
& see how far voltage drops. It's hard to get the time domain
resolution on a digital meter that you see on the Dynon graph, so you
might try pulling the Dynon fuse, & power the Dynon with a wire
directly to the battery B+ terminal so it can see true battery voltage
during cranking. Remember to run a ground wire from the Dynon directly
to the battery ground terminal also, if you try this.
If you see your voltage drops going to ~9-10volts instead of 6-8volts,
then you probably have some bad connections somewhere in the circuit.
If the battery is truly dropping to 6volts during cranking, then it's
either not fully charged, or defective. (Or you've got a bad starter.)
http://www.matronics.com/contribution
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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todehnal
Joined: 06 Sep 2015
Posts: 2
Location: Kentucky Lake Area, KY
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| Posted: Wed Sep 09, 2015 8:04 am Post subject: Re: Engine Starter Stalling |
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I did build my RV-12 under EAB rules. Pretty sure Dynon is monitoring the voltage at the Avionics Bus, right at the amperage shunt. As far as the starter, I have hooked a +12 volt lead directly to it, and it functions flawlessly. I also have removed, cleaned, and reattached every connection from the battery plus, through the master relay, through the start relay, and starter, and back to the battery ground post, with no change. I guess my real question should be, is it a problem when the active starter voltage dips below 7 volts? Not sure what I should typically be seeing here........Tom
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_________________
RV-12 with Skyview Panel built EAB by my wife & I.
First Flight: 11/21/13. It's a keeper....Tom |
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ceengland7(at)gmail.com
Guest
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| Posted: Wed Sep 09, 2015 8:48 am Post subject: Engine Starter Stalling |
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On 9/9/2015 11:04 AM, todehnal wrote:
| Quote: |
I did build my RV-12 under EAB rules. Pretty sure Dynon is monitoring the voltage at the Avionics Bus, right at the amperage shunt. As far as the starter, I have hooked a +12 volt lead directly to it, and it functions flawlessly. I also have removed, cleaned, and reattached every connection from the battery plus, through the master relay, through the start relay, and starter, and back to the battery ground post, with no change. I guess my real question should be, is it a problem when the active starter voltage dips below 7 volts? Not sure what I should typically be seeing here........Tom
--------
RV-12 with Skyview Panel built EAB by my wife & I.
First Flight: 11/21/13. It's a keeper....Tom
Does that mean that you *started the engine* by hooking a battery lead
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directly to the starter? Because if you removed the starter & just spun
it up with the battery, that doesn't give you much useful info that you
didn't already know (that the windings have some continuity and the
bearings allow it to turn).
If you're monitoring voltage anywhere except at the battery terminals,
you really need to know actual battery voltage *at the battery posts*
before proceeding further. If it's staying higher than 8-10 volts while
cranking, and you're seeing 6 volts at the remote monitoring point,
you've got high resistance somewhere in the power circuit between
battery & monitoring point. Don't forget that every connection using a
terminal on a wire is really *two* connections: the transition in the
bolted joint, and the joint between the terminal and the wire itself,
whether crimped or soldered.
Voltage will typically drop to between 8 & 10 volts while under starting
load. Dropping to 6 volts can often cause electronics to drop off line,
& may cause relays to drop out, as well. Try eliminating 'stuff' that's
between the battery & starter.
Eliminate the master contactor by putting both heavy terminals on the
same post (this will obviously power up the plane even with the master
switch off). Try starting the engine & see if your symptoms change for
the better. If so, likely bad contacts in the master contactor.
No change? return to 'normal' configuration & move on.
Temporarily eliminate the wing spar interlock by jumping across it's
contacts, & try starting. If symptoms change, perhaps the interlock is
misadjusted or its contacts are flaky, causing it to be intermittent
with vibration.
The above are just examples; follow the power circuit and eliminate or
'bridge' each joint in sequence.
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Wed Sep 09, 2015 9:05 am Post subject: Engine Starter Stalling |
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At 07:01 AM 9/9/2015, you wrote:
| Quote: | --> AeroElectric-List message posted by: "todehnal" <tomscub(at)gmail.com>
Hi Guys, New kid on the block, and I am looking for some advice. I have been having starter stall on cold starts. It will stop the prop a couple of times, and then spin up and start fine. I have been chasing this for a couple of months now. By the way, this is a Rotax powered RV-12. I know that when this happens the starter solenoid chatters. I can hear it. This chatter is caused by another starter circuit interrupt on the RV-12 called the spar pin relay. This safety device ensures that the removable wings spar pins are fully engaged, then completed the circuit to the start relay. I am now analyzing the battery. I downloaded data from the Dynon skyview, searched the spreadsheet and came up with a chart that shows the battery voltage during a typical start. If someone could take a look at the link below and offer some thoughts about the battery performance, or offer other advice, I would greatly appreciate it. Neat chart, and you can see the compression cycles on the chart. Thanks.........Tom |
As Charlie points out, without knowing exactly where
the Dynon gets its data, the value of that data
is weak. The plots show that the voltage doesn't drop
below 8v or so . . . normally too high for contactor
'chatter'. I suspect that the data is being gathered at
the bus . . . which may well be a voltage different than
what drives the starter and/or it's control contactor.
Is this a new condition? What size and how old the
battery. Have you load checked it? Is there a wiring diagram for
the system you can share? Just for grins, you might
try clipping a charge car battery across the ship's
battery and repeat the cold start experiment to
see if there's a marked difference in behaviors.
Bob . . . [quote][b]
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tim2542(at)sbcglobal.net
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| Posted: Wed Sep 09, 2015 10:54 am Post subject: Engine Starter Stalling |
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Don't forget the ground side of the circuit, you can have high resistance anywhere. One diagnostic method is to put a volt meter in series with the ground circuit, ie one probe on the battery negative post and the other on the engine case. You should see about a volt or less while cranking. Do the same on the positive side next, battery positive post and the other on the terminal on the starter. Anything over a volt or so and you have high resistance in the circuit, which can then be easily found by moving the probe backwards from the starter measuring at each terminal toward the battery.
Having said all that, your chattering solenoid is pretty typical of a weak battery.
Tim Andres
| Quote: | On Sep 9, 2015, at 9:50 AM, Charlie England <ceengland7(at)gmail.com> wrote:
> On 9/9/2015 11:04 AM, todehnal wrote:
>
>
> I did build my RV-12 under EAB rules. Pretty sure Dynon is monitoring the voltage at the Avionics Bus, right at the amperage shunt. As far as the starter, I have hooked a +12 volt lead directly to it, and it functions flawlessly. I also have removed, cleaned, and reattached every connection from the battery plus, through the master relay, through the start relay, and starter, and back to the battery ground post, with no change. I guess my real question should be, is it a problem when the active starter voltage dips below 7 volts? Not sure what I should typically be seeing here........Tom
>
> --------
> RV-12 with Skyview Panel built EAB by my wife & I.
> First Flight: 11/21/13. It's a keeper....Tom
Does that mean that you *started the engine* by hooking a battery lead directly to the starter? Because if you removed the starter & just spun it up with the battery, that doesn't give you much useful info that you didn't already know (that the windings have some continuity and the bearings allow it to turn).
If you're monitoring voltage anywhere except at the battery terminals, you really need to know actual battery voltage *at the battery posts* before proceeding further. If it's staying higher than 8-10 volts while cranking, and you're seeing 6 volts at the remote monitoring point, you've got high resistance somewhere in the power circuit between battery & monitoring point. Don't forget that every connection using a terminal on a wire is really *two* connections: the transition in the bolted joint, and the joint between the terminal and the wire itself, whether crimped or soldered.
Voltage will typically drop to between 8 & 10 volts while under starting load. Dropping to 6 volts can often cause electronics to drop off line, & may cause relays to drop out, as well. Try eliminating 'stuff' that's between the battery & starter.
Eliminate the master contactor by putting both heavy terminals on the same post (this will obviously power up the plane even with the master switch off). Try starting the engine & see if your symptoms change for the better. If so, likely bad contacts in the master contactor.
No change? return to 'normal' configuration & move on.
Temporarily eliminate the wing spar interlock by jumping across it's contacts, & try starting. If symptoms change, perhaps the interlock is misadjusted or its contacts are flaky, causing it to be intermittent with vibration.
The above are just examples; follow the power circuit and eliminate or 'bridge' each joint in sequence.
|
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