Today's Message Index:
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1. 03:38 PM - Re: Z101 in an RV-10 (Robert L. Nuckolls, III)
2. 07:06 PM - Re: Z101 in an RV-10 (Watzlavick)
3. 07:44 PM - Re: Re: Z101 in an RV-10 (Charlie England)
4. 07:51 PM - Re: Z101 in an RV-10 (Watzlavick)
Message 1
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| Subject: | Re: Z101 in an RV-10 |
>In the RV-10, the battery and battery contactor are located in the tailcone.
>Looking at the schematic, I will need to run a large conductor (probably 2AWG)
>forward from the contactor to the starter.
4AWG is fine
>My concern is that the "fat wire tie point" for the battery bus, aux bus,
>and engine bus will need a second large conductor run forward (my aux and
>engine busses have decent loads due to IFR and EFII equipment). This
>seems like it will add considerable weight...
"second large conductor", "decent loads", "considerable weight"
are not quantified. The best decisions are made with calculated
data. What are the loads on conductors to those busses from
their aux power relays?
>The only solution I can imagine would be to leave the battery in the tail
>and move the battery contactor forward to the firewall.
No. Battery contactors go next to batteries as do
the aux power relays. See the (*) symbol on the
upstream conductors?
>This would leave a long length of unprotected wire
Not recommended nor necessary
>This might become more clear as I start to actually run wires but
>for now it seems less than ideal. Thoughts?
You have two aux bus feeders. I suspect 10AWG would be
quite sufficient . . . but do the numbers. What are the
loads and how long are they?
10AWG is on the order of .04 lb/ft so two 8' runs
would add about 10 ounces. An 8' run of 2AWG is
right at 2 pounds; 4AWG is about 1.2 pounds. So
down-size to 4AWG and add two runs of 10AWG and
it's about a wash.
Your exact results may vary . . .
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 2
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| Subject: | Re: Z101 in an RV-10 |
I'm also considering Z101 for my RV-10 but I'm concerned about the always hot B-lead
from the aux alternator to the rear mounted battery in a crash situation.
I see 3 options: 1) add another contactor between the aux alternator and battery,
2) use Z-12 instead, or 3) don't fret about the hot B-lead. I've searched
through the archives quite a bit and there doesn't seem to be a good consensus
whether having an always hot lead with a rear battery is a really bad idea
or not.
A different question if I may - With Z-101 and the aux alt off, if the battery
contactor fails open (unlikely I know) but the main alternator is still running,
the battery would then charge via the diode between the main and Endurance
bus assuming that relay is closed. Depending on the battery charge state, It
seems possible the charge current could blow the fuseable link between the battery
and Endurance bus, taking the battery off line. Seems like a diode is needed
between the Endurance bus and battery to prevent that. Or is the battery
charge current sufficiently limited?
-Robert
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=503084#503084
Message 3
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| Subject: | Re: Z101 in an RV-10 |
On 9/7/2021 9:05 PM, Watzlavick wrote:
>
> I'm also considering Z101 for my RV-10 but I'm concerned about the always hot
B-lead from the aux alternator to the rear mounted battery in a crash situation.
I see 3 options: 1) add another contactor between the aux alternator and
battery, 2) use Z-12 instead, or 3) don't fret about the hot B-lead. I've searched
through the archives quite a bit and there doesn't seem to be a good consensus
whether having an always hot lead with a rear battery is a really bad
idea or not.
>
> A different question if I may - With Z-101 and the aux alt off, if the battery
contactor fails open (unlikely I know) but the main alternator is still running,
the battery would then charge via the diode between the main and Endurance
bus assuming that relay is closed. Depending on the battery charge state, It
seems possible the charge current could blow the fuseable link between the battery
and Endurance bus, taking the battery off line. Seems like a diode is
needed between the Endurance bus and battery to prevent that. Or is the battery
charge current sufficiently limited?
>
> -Robert
The 10ga aux B lead is protected by the 14ga fusible link. I didn't try
to read the Z101B notes, but I'd assume that wire sizes for the aux alt
assume a smaller alternator (typical B&C, etc vac pad mounted alternator
@ ~30A max). The 10ga wire with 14ga fusible link should work for 30A.
--
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Message 4
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| Subject: | Re: Z101 in an RV-10 |
Good point - after I sent the email, I started looking at charge currents and you're
right - it's limited by the alternator output. I guess you could call the
lack of a diode there a feature in that it allows the battery to be charged
via an alternate path. It also seems like it would provide some load stabilization
for the alternator.
-Robert
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=503086#503086
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