Today's Message Index:
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0. 12:21 AM - Please Make A Contribution To Support Your Lists (Matt Dralle)
1. 07:57 AM - Re: Re: Battery contactor versus circuit breaker (Noel Loveys)
2. 10:41 AM - Re: Covering up the contactors (James Kilford)
3. 04:57 PM - Re: instrument ground loops? (Robert L. Nuckolls, III)
4. 05:02 PM - Re: Covering up the contactors (Robert L. Nuckolls, III)
5. 09:09 PM - Re:battery location change (James Robinson)
6. 10:25 PM - Re: Re:battery location change (Peter Harris)
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| Subject: | Please Make A Contribution To Support Your Lists |
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Message 1
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| Subject: | Re: Battery contactor versus circuit breaker |
To begin with regardless of the protective device protection is downstream
from the battery after the protection. So in fact the safest thing to do
would be to have the protection actually built into the battery. That not
being available the next best thing is to put the protection device next to
the battery. Cessna for one actually puts the protection right on the
outside of the battery box on the C-180, C-185. The advantage of using a
relay is that if you see a hard landing coming your way you can with the
flick of a switch (on the panel) you can isolate a remote installed battery.
With a circuit breaker in the same location it would require a short to
cause the breaker to open... That could be the spark you really wouldn't
want.
I've always seen the main cable for the starter come directly off the
battery to a very close solenoid ( another relay) then from the solenoid to
the starter. As Bob mentioned last week this doesn't give you any
protection from the solenoid jamming closed which aside leaving the heavy
cable to the starter energized but it would also cause the starter to run
continuously to destruction with no method of shut down. I have seen bendix
units with integral solenoids jam in cars but never the remote solenoid but
it's worth considering what bob mentioned and if you have a master relay
that can handle the current of the starter it would be a good idea to wire
the starter through it as an additional method of stopping the starter if
the starter solenoid jams closed.
So in short you are reading Bob correctly.
BTW you should also have a breaker or at least a switch between the
generator and the panel. In the event of an impending accident battery
isolation is a great thing to have.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of mmayfield
Sent: November 4, 2010 7:34 AM
Subject: AeroElectric-List: Re: Battery contactor versus circuit breaker
<mmayfield@ozemail.com.au>
Noel,
on a couple of photos I've seen of what I believe is a similar setup (and on
this same plane type), the batt c/b was located right next to the battery
where one might otherwise find a battery contactor on other types, thus it
would seem to offer supply wire protection.
The schematic is exceedingly simple: Batt, to batt c/b, to master switch,
to bus. All in a straight line.
I guess I'm enquiring as to the relative wisdom of this type of main
supply-wire protection versus using a contactor. Bear in mind that it's a
very simple electrical system in either case.
If I'm reading what Bob wrote correctly, he is saying that a contactor
allows virtual complete isolation of the battery in an emergency and
consequent reduction of hazard/risk, and thus might be preferable to a
non-accessible battery circuit breaker in even such a simple system with a
low power alternator as this.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=318106#318106
Message 2
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| Subject: | Re: Covering up the contactors |
Thanks for that Bob. Even after a couple of years on the firewall in
the hangar, the contactors are already quite dull. They're not
corroded, as I put some Vaseline (petroleum grease) on them and the
various connections.
That Bonanza certainly looks pristine! Is there a trick to keeping
everything so sparkling?
James
On 6 November 2010 05:04, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 08:01 PM 11/5/2010, you wrote:
>>
>>
>> Gents,
>>
>> I have three contactors mounted on the engine side of the firewall,
>> along with a battery. Everything else (regulator, busses, etc.) is
>> inside the cabin. Is there any value in covering up my contactors, or
>> are they alright as they are?
>
> Here's the firewall of an A36 Bonanza.
>
> http://aeroelectric.com/Pictures/Wiring_Technique/A36_Firewall_A.jpg
>
> http://aeroelectric.com/Pictures/Wiring_Technique/A36_Firewall_B.jpg
>
> with contactors, fuseblocks, current limiters, etc
> hung out in behind Continental and everybody.
> I think your electro-whizzies will be fine without
> extra-ordinary cover.
>
>
> Bob . . .
>
>
Message 3
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| Subject: | instrument ground loops? |
At 11:53 PM 11/6/2010, you wrote:
>
>Bob,
>
>Sort of related...
>
>My LR3C voltage regulator has surprisingly large mounting holes. 5/16 IIRC.
>Is this because there should be an isolation washer to prevent the bolts and
>case from touching the metal mounting surface? I don't have any bolts with
>such a large diameter and so short of grip length. I was considering
>drilling for #8 screws in between the factory holes until I saw this thread.
Good question . . .
The footprint for the LR series regulators was
cloned from a series of production regulators
and I don't even remember now who's devices . . .
They were commonly mounted on nut plates but with #8
hardware and flat washers. I don't know why they would
choose to do this other than to have a lot of tolerance
for hole locations on the mounting plate. You can drill
new holes or put washers under the heads of smaller screws.
In about 25 years and thousands of sold units, you're
the first I can recall that noticed and asked the
question. I think it was a Lamar footprint and we simply
cloned it with the idea of making it a drop-in replacement.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 4
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| Subject: | Re: Covering up the contactors |
At 12:37 PM 11/7/2010, you wrote:
Thanks for that Bob. Even after a couple of years on the firewall in
the hangar, the contactors are already quite dull. They're not
corroded, as I put some Vaseline (petroleum grease) on them and the
various connections.
That Bonanza certainly looks pristine! Is there a trick to keeping
everything so sparkling?
I took that on the production line . . . so it's a sure
bet that the 'shine' goes away after a few years. But
shine doesn't help the electrons get from point-A to
point-B. The gas tight joint and designing switching
devices to meet service life in the proposed application
side steps the lack of luster.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
Message 5
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| Subject: | Re:battery location change |
Good Evening Bob
I have the 2 alternator , 2 batteries, setup in my Glasair. this has been a
problem free system since it's inception. I am needing to change the location
of the batteries for weitht and balance and interference problems. Currently
the batteries and the all the control solenoids are on the engine side of the
firewall with 2 power and 1 gnd thru the firewall connections. Do I need to add
2 more thru the firewall connections to get the power back out to the solenoids
from the repositioned batteries or is there a more efficient way to reconfigure
the system. I am not at home so I can't consult the original diagram. Thanks
as always for your expert help in these matters.
Jim
James Robinson
Glasairlll N79R
Spanish Fork UT U77
Message 6
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| Subject: | Re:battery location change |
Hi Bob,
Do you have a protection circuit to protect against regulator-rectifier
failure for the PM alternator as used on the Jabiru 3300? I have installed
the OV crowbar circuit but does this stop voltage excess say 15-20V? I am
getting interference affecting the ECU as I have fuel injected the engine. I
will test the Vreg output in a couple of days but need to be sure I have
this protection if possible anyway.
Thanks
Peter
Quickie Q-200Jabiru
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