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Patrick Nelson
Joined: 22 Nov 2020
Posts: 4
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 Posted: Tue Nov 24, 2020 12:01 pm Post subject: Z101B Questions |
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Hello All,
I'm new to the community and trying to come up with an electrical system design I'm happy with for SDS EFI. I started with something based on Z-14, but with modifications to make it suitable for SDS - this could be an entire separate topic. I have since found Z101B and I really like it so far!
Has anyone implemented Z101B yet? I had a few questions about the design:
1. Has anyone tried to measure battery current instead of alternator current? I'm guessing this won't work easily because there are too many fat wires to pass through the hall effect sensor.
2. I noticed the aux alternator B-lead is always hot. This could cause the battery to drain if one of the alternator diodes fails. I don't see a quick fix. Any suggestions?
3. Any reason the functions of "alt bus" and "alt alternator" should be tied together? Seems like they can be operated independently with separate switches and doing so seems less confusing - for me at least.
4. I was planning to have the main bus in the cabin so I'll need to add an ANL fuse between the battery contactor and main bus. I guess this is more of a comment than a question. Along the same lines, shouldn't the brownout bus feed through the contactor have an ANL fuse?
5. Any reason to not power the brownout booster from the starter side of the start contactor? This would reduce the load being switched by the start button. I really don't want those contacts to weld.
Any comments/suggestions appreciated. Thank you everyone!
-Patrick
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user9253
Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan
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| Posted: Tue Nov 24, 2020 2:36 pm Post subject: Re: Z101B Questions |
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Lots of builders measure battery current instead of alternator current.
Just don't measure starter motor current.
Most planes do not have fuses protecting the main power bus because a fuse
creates more of a hazard than an unprotected bus and feeder. The pilot
can shut off the master battery contactor if necessary.
5. Yes, timing. The brownout booster needs to be powered up before the starter contactor closes.
The more complicated the electrical system is, the more likely that something will go wrong.
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Joe Gores |
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nuckolls.bob(at)aeroelect
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| Posted: Tue Nov 24, 2020 4:30 pm Post subject: Z101B Questions |
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At 02:01 PM 11/24/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: "Patrick Nelson" <panelsonms(at)hotmail.com>
Hello All,
I'm new to the community and trying to come up with an electrical system design I'm happy with for SDS EFI. I started with something based on Z-14, but with modifications to make it suitable for SDS - this could be an entire separate topic. I have since found Z101B and I really like it so far! |
Welcome aboard my friend!
| Quote: | Has anyone implemented Z101B yet? I had a few questions about the design:
1. Has anyone tried to measure battery current instead of alternator current? |
been there, done that, nobody does it any more . . . at least
not on single engine aircraft. Battery ammeter readings are
not helpful data in flight. In fact, the only ammeter I recall
being really useful on an SE aircraft was the A36 Bonanza with
prop de-ice. The system only powered one blade at a time
and having an ammeter in series with prop-deice would
offer a gross indication for loss of one heater circuit.
But then, you'd probably know something was out of whack
when prop balance was compromised due to ice accumulation
on one blade.
If I were going to fit an airplane with the single most
valuable indicator for loss of system performance
it would be ACTIVE NOTIFICATION of low volts. This
is something that requires pre-planned actions on
the part of a pilot. Ammeters are sort like fox-tails
on your antenna . . . or spinner hub caps.
| Quote: | | I'm guessing this won't work easily because there are too many fat wires to pass through the hall effect sensor. |
How would you use those numbers if you had them?
| Quote: | 2. I noticed the aux alternator B-lead is always hot. This could cause the battery to drain if one of the alternator diodes fails. I don't see a quick fix. Any suggestions?
|
No fix necessary. Diodes just don't do that any
more and then it would require more than one to
cause a drain which would be mitigated by the b-lead
fuse.
| Quote: | | 3. Any reason the functions of "alt bus" and "alt alternator" should be tied together? Seems like they can be operated independently with separate switches and doing so seems less confusing - for me at least. |
They share a switch but are not 'tied' together. The switch
serves the same function as battery master . . . 3 position
switch that closes the relay first and alternator next.
| Quote: | | 4. I was planning to have the main bus in the cabin so I'll need to add an ANL fuse between the battery contactor and main bus. I guess this is more of a comment than a question. Along the same lines, shouldn't the brownout bus feed through the contactor have an ANL fuse? |
No, those are power distribution FAT wires. Those
are never fused in light aircraft. Probability of
a fault that puts a FAT wire at risk is nil. You can
add one if you wish but there's no foundation in
historical risk assessment that supports it.
| Quote: | 5. Any reason to not power the brownout booster from the starter side of the start contactor? This would reduce the load being switched by the start button. I really don't want those contacts to weld.
|
It's a function of timing. The brownout booster needs
to be spooled up and ready to take a load BEFORE
the battery is burdened with starter inrush current.
It's just milliseconds but they're important. If
you're worried about the starter switch then
do the load analysis to confirm the switch's
suitability to task.
Band-aids on worries are seldom a good thing . . .
modifications to meet requirements are never
a bad thing.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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Patrick Nelson
Joined: 22 Nov 2020
Posts: 4
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| Posted: Fri Nov 27, 2020 9:12 pm Post subject: Re: Z101B Questions |
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Thank you for the replies!
| Quote: | | How would you use those numbers if you had them? |
It terms of battery current, that's what I'm used to seeing in other planes and it can be used to detect an alternator failure. However, I see your point of using the voltmeter to detect an alternator failure instead and alternator current gives a more useful indication of total electrical load.
| Quote: |
No fix necessary. Diodes just don't do that any
more and then it would require more than one to
cause a drain which would be mitigated by the b-lead
fuse.
|
I looked more at the BC410-H alternator I'm planning to use for the aux alternator and I think you're right that it won't be a problem. There should be no internal connection between the B and F terminals, in theory.
I saw an example in a car where an alternator diode being shorted caused the charging system light on the dashboard to stay lit - even with the car completely shut off.
| Quote: |
They share a switch but are not 'tied' together. The switch
serves the same function as battery master . . . 3 position
switch that closes the relay first and alternator next.
|
Please excuse my still learning electrical systems, but this doesn't make sense to me. The aux alternator provides power to the battery side of the main contactor. There's not a second battery and "aux master" like you'd have with a Z-14 setup. One function of this switch is to turn on the aux alternator.
The other feature of this switch is to provide an alternate power source to the brownout bus. This could be used as a "clearance delivery" feature or like the "E-bus Alternate Feed" as exists on some of the other schematics (like Z-10). I'm still not understanding why these share a switch.
Why would you want the aux alternator field powered to use the "clearance delivery" function? Edit: Disregard this question. The switch will be in "batt" position for clearance delivery.
Thank you both for answering the question about the power source for the brownout booster. That completely makes sense and I'm glad I asked 
Thanks again for the info!
-Patrick
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nuckolls.bob(at)aeroelect
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| Posted: Sun Nov 29, 2020 7:40 pm Post subject: Z101B Questions |
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| Quote: | | Please excuse my still learning electrical systems, but this doesn't make sense to me. The aux alternator provides power to the battery side of the main contactor. There's not a second battery and "aux master" like you'd have with a Z-14 setup. One function of this switch is to turn on the aux alternator. |
It's a two-stage operation that brings the aux alternator
on line AFTER closing the auxillary feed relay
between the battery and AUX bus.
| Quote: | The other feature of this switch is to provide an alternate power source to the brownout bus. This could be used as a "clearance delivery" feature or like the "E-bus Alternate Feed" as exists on some of the other schematics (like Z-10). I'm still not understanding why these share a switch.
Why would you want the aux alternator field powered to use the "clearance delivery" function? |
It doesn't. Raise the switch one notch and you've
got the aux bus hot without powering the aux alternator
field. See chapter in the 'Connection on special switch
functions.
| Quote: | > 5. Yes, timing.
Thank you both for answering the question about the power source for the brownout booster. That completely makes sense and I'm glad I asked
Thanks again for the info!
-Patrick
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You are welcome
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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