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Sam
Joined: 18 May 2008
Posts: 135
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 Posted: Mon Jul 27, 2009 7:56 am Post subject: Crossfeed |
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I have an all electric plane and have attempted to emulate Z19-RB.
Both batteries are the same size, but I am intending on starting on the main battery only. My alternator-out load analysis shows around 17 amps to keep it in the air, though I think I can drop that to 10.
The "keep the engine running" components may run off either bus, but the endurance bus is just connected to the main.
Could I install a crossfeed switch between the main and engine batteries, without a contactor? It would allow me to use the engine battery for the endurance bus, to supplement the main battery. That would also allow me to simultaneously charge both batteries without engaging the engine battery contactor.
I'll try and attach a pdf.
BTW, after a year and a half, I am somewhat back in the air, though many bugs remain.
Sam
www.samhoskins.blogspot.com
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_________________
Sam Hoskins
www.samhoskins.blogspot.com |
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nuckolls.bob(at)aeroelect
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| Posted: Fri Jul 31, 2009 11:43 am Post subject: Crossfeed |
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At 10:32 AM 7/27/2009, you wrote:
| Quote: | I have an all electric plane and have attempted to emulate Z19-RB.
Both batteries are the same size, but I am intending on starting on
the main battery only. My alternator-out load analysis shows around
17 amps to keep it in the air, though I think I can drop that to 10.
|
Okay, what are your design goals for battery only
endurance?
| Quote: | The "keep the engine running" components may run off either bus, but
the endurance bus is just connected to the main.
Could I install a crossfeed switch between the main and engine
batteries, without a contactor?
|
Obviously, yes. But 30A always hot wires to a panel mounted
switch? You're stacking lots of switches and
options together that PRESUMES you'll be making good
and useful decisions when things aren't going right.
You also appear to be stacking multiple failures onto
a single tank full of gas.
| Quote: | It would allow me to use the engine battery for the endurance
bus, to supplement the main battery. That would also allow me to
simultaneously charge both batteries without engaging the engine
battery contactor.
|
Hmmmm . . . the whole idea behind Z-19 was to partition
duties for the two batteries batteries of known condition.
If there's rationale for paralleling them, perhaps one larger
battery is more appropriate?
With respect to hangar maintenance for dual batteries, how
about dual battery maintainers? Give each their own accessory
plug to a wire off the battery bus protected with a 5A
fuse??
If you're worried about having total battery energy
available for any and all duties aboard the aircraft,
what's the failure mode that prompts the design
goal?
| Quote: | I'll try and attach a pdf.
|
Nice job on the drawing . . .
| Quote: | BTW, after a year and a half, I am somewhat back in the air, though
many bugs remain.
|
Yup, it's no different in the development of TC
aircraft. Hopefully we slay all the dragons during
pre-cert flight testing and shepherding the first
dozen or so airplanes down the line. The NICE thing
about dead-dragons in the factory is that the outcome
benefits lots of future airplanes. Your website for
sharing your own hunting successes is a good and useful
thing . . .
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
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Sam
Joined: 18 May 2008
Posts: 135
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| Posted: Sat Aug 01, 2009 4:56 am Post subject: Crossfeed |
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Answers to questions/comments embedded below.
On Fri, Jul 31, 2009 at 2:42 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)>
At 10:32 AM 7/27/2009, you wrote:
| Quote: | I have an all electric plane and have attempted to emulate Z19-RB.
Both batteries are the same size, but I am intending on starting on the main battery only. My alternator-out load analysis shows around 17 amps to keep it in the air, though I think I can drop that to 10.
|
Okay, what are your design goals for battery only
endurance?
|
I understand that I have added complication in order to persue this electronic ignition/injection path, and I am not flying the same plane as before. (The wire count is now over 150, for this little plane. My old wire count was about 70). If I could get a reliable 1.5 hours of flight time, from the time of an alternator faliure, I could deal with that. I fly day VFR, but sometimes fly over the mountains and the Ozarks.
| Quote: |
| Quote: | The "keep the engine running" components may run off either bus, but the endurance bus is just connected to the main.
Could I install a crossfeed switch between the main and engine batteries, without a contactor?
|
Obviously, yes. But 30A always hot wires to a panel mounted
switch? You're stacking lots of switches and
options together that PRESUMES you'll be making good
and useful decisions when things aren't going right.
You also appear to be stacking multiple failures onto
a single tank full of gas.
|
It's always a question about how far to take this "redundancy" issue.
I was recently thrown for another loop when Tracy Crook informed me I should have power supplied simultaneously to both the power inputs on the EC3 controller. I have not yet figured how to do that without adding any more switches. I had one scenario figured out, but it required the ON-ON-OFF switch. It turns out the switch is too wide to fit into the existing rows or switched. For right now, I am using an unwieldy workaround.
| Quote: |
| Quote: | It would allow me to use the engine battery for the endurance bus, to supplement the main battery. That would also allow me to simultaneously charge both batteries without engaging the engine battery contactor.
|
Hmmmm . . . the whole idea behind Z-19 was to partition
duties for the two batteries batteries of known condition.
If there's rationale for paralleling them, perhaps one larger
battery is more appropriate?
|
I already have the two batteries installed and I like the idea of using a timed replacement/rotation program. I would need a really complelling reason to backtrack all that.
| Quote: |
With respect to hangar maintenance for dual batteries, how
about dual battery maintainers? Give each their own accessory
plug to a wire off the battery bus protected with a 5A
fuse?? |
I could do that. The backup battery is easily accessible and the main backup is harder to get to, so that is simple and works out for charging.
| Quote: |
If you're worried about having total battery energy
available for any and all duties aboard the aircraft,
what's the failure mode that prompts the design
goal?
|
Of course, the worst failure would be the alternator giving up the ghost. At that point, electrons become as valuable as fuel. If the alternator is gone, I need to be able to have available all the juice in each of the batteries.
| Quote: |
| Quote: | I'll try and attach a pdf.
|
Nice job on the drawing . . .
|
Thanks. I use SolidEdge 2D by Seimens. It's free. It's the most similar to ME10/CoCreate, which we used back at the explosives factory.
| Quote: |
| Quote: | BTW, after a year and a half, I am somewhat back in the air, though many bugs remain.
|
Yup, it's no different in the development of TC
aircraft. Hopefully we slay all the dragons during
pre-cert flight testing and shepherding the first
dozen or so airplanes down the line. The NICE thing
about dead-dragons in the factory is that the outcome
benefits lots of future airplanes. Your website for
sharing your own hunting successes is a good and useful
thing . . .
|
I figure the best I can give back is to make a good record for others to follow or to reject, as it suits them.
Sam
www.samhoskins.blogspot.com
[quote]
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
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_________________
Sam Hoskins
www.samhoskins.blogspot.com |
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