Today's Message Index:
----------------------
1. 04:06 AM - Re: Grounding questions (KITFOXZ@aol.com)
2. 11:51 AM - Re: Wiring VM1000 for dual alternators (MARTIN EMRATH)
3. 04:31 PM - Re: Re: Wiring VM1000 for dual alternators (Robert L. Nuckolls, III)
4. 04:37 PM - Re: Fluctuating Ammeter (Robert L. Nuckolls, III)
5. 04:44 PM - Re: 10631 Lee (Robert L. Nuckolls, III)
6. 05:29 PM - Re: Grounding questions (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Grounding questions |
--> AeroElectric-List message posted by: KITFOXZ@aol.com
In a message dated 7/2/2003 9:55:08 AM Eastern Standard Time, DHPHKH@aol.com
writes:
> <<The two batteries are in a common battery box and their negative
> terminals
> >are bolted together with a 1/4" bolt.>>
>
> Just a thought: May not be wise to bolt two heavy batteries together at
> the terminals. A flexible connection seems more appropriate.
>
> Dan
>
>
Dan, You are right on point here. This is a VERY important detail. Bolting
two large (heavy) masses together at a single point is begging for trouble.
Even if the battery pair were very snug and cannot move a micrometer in the
battery box, I would not subject the battery posts to this stress. A very
flexible braided jumper wire with terminal connections at battery posts is a must.
John P. Marzluf
Columbus, Ohio
Kitfox Outback (out back in the garage)
Message 2
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| Subject: | Re: Wiring VM1000 for dual alternators |
--> AeroElectric-List message posted by: MARTIN EMRATH <emrath@comcast.net>
Bob: Is the 0.7 volt drop due to the losses in the master contactor?
Marty in Brentwood TN
Time: 08:56:21 AM PST US
From: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Subject: Re: AeroElectric-List: Wiring VM1000 for dual alternator
installation
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
At 05:32 AM 6/25/2003 -0400, you wrote:
>--> AeroElectric-List message posted by: "Treff, Arthur"
><Arthur.Treff@Smartm.com>
>
>Listers,
>
>I'm wiring my RV-8 with Z-13. My ammeter will the embedded in the
Vision
>MIcrosystems VM-1000 display.
>
>My questions are:
>1) What would be the consequence if I connected the leads from both
>ammeter shunts to the VM-1000? Since both alternators would be
operating
>at different times wouldn't the display just show the current from
which
>ever alternator was switched on? No doubt I'm missing something,
please
>poke holes in my logic.
I got a note from Vision Microsystems that answered questions
I had on how their transducers were wired. I've published a suggested
wiring diagram for dual ammeter transducers on the VM1000 at
<http://216.55.140.222/temp/VM1000_Dual_Bus.pdf>
Consider that you might do quite nicely without putting
an ammeter sensor on the aux alternator. If the bus voltage
is staying above 13.0 volts then you're certainly not overloading
the aux alternator. Besides, your en-route load analysis
needs to be accomplished before first flight. You KNOW
what the maximum auxiliary alternator loads are going to
be long before you ever need to load that alternator.
>2) For those who have used a primary and an E bus and a display like
the
>VM-1000, where in the circuit did you wire the voltmeter? Any reason
to
>have a voltmeter on the main bus as well as the E-bus? OOps, that's a
>dumb question, I think I just answered it myself. Current is very
>important to system health, but knowing if the voltage falls below
>alternator output (#1 or #2) is all that really matters, yes? Having
said
>that, my logic is that putting a single voltmeter accross the pnl
ground
>plane to the started contactor would do the job. Fire away, what am I
missing?
If power to operate the VM1000 fits into your power
budget for sustained en route operations with the aux alternator
(and I would think 8+ amps is plenty) then run the
VM1000 from the e-bus and be aware that voltage readings
for normal operations are 0.7 volts lower than actual.
Momentary closure of the alternate feed switch will give
you the real bus voltage and show that the alternate feed
path is intact.
Bob . . .
Message 3
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| Subject: | Re: Wiring VM1000 for dual alternators |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 01:48 PM 7/3/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: MARTIN EMRATH <emrath@comcast.net>
>
>Bob: Is the 0.7 volt drop due to the losses in the master contactor?
>Marty in Brentwood TN
No, from e-bus normal feedpath diode.
Bob . . .
Message 4
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| Subject: | Re: Fluctuating Ammeter |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 02:32 AM 7/3/2003 -0400, you wrote:
>--> AeroElectric-List message posted by: "Richard V. Reynolds"
><rvreynolds@macs.net>
>
>With the engine running and the alternator on, the ammeter fluctuates
>between +60/-60 amps
>with all loads on. As the loads are reduced, i.e. the landing lights,
>strobes, and nav
>lights are turned off, the fluctuations reduce to +5/-5 amps.
>
>The battery voltage is 13.6 volts before start and 15.2 volts with the
>alternator on as
>measured with a digital voltmeter. The voltage does not appear to be
>fluctuating.
>
>I presume the RV has the standard Vans regulator and alternator.
>
>Any thoughts on the cause.
>
>Richard Reynolds for a friend
more than half the time, this is a manifestation of
voltage regulator instability due to excessive wiring
resistance between the bus and the regulator. 15.2 is
a tad high also and could be yet another manifestation
of resistance . . .
Try an experiment. Temporarily disconnect existing feedpath
between input of regulator and bus. Make temporary connection
between the input of your regulator and battery (+) terminal
with a piece of hefty wire like 14 to 18AWG. Fire engine up,
measure voltage at battery terminal and observe behavior of
ammeter. If it settles down and votlage at battery moves
down toward a more normal reading, then the problem lies in
the normal feedpath between bus and regulator. Wire size,
terminals, threaded fasteners, and internal resistance of
breakers and switches can all add up to a value sufficient
to upset the regulator.
Be sure to break the temporary connection from battery (+)
when the experiment is over . . . left on too long
might overheat your alternator rotor and/or run the battery
down.
Bob . . .
Message 5
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--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 01:58 AM 7/3/2003 +0000, you wrote:
>Below is the result of your inquiry. It was submitted by
>John Lee (borgny@rconnect.com) on Wednesday, July 2, 2003 at 18:58:27
>
>Wednesday, July 2, 2003
>
>John Lee
>
>,
>Email: borgny@rconnect.com
>Comments/Questions: Dear Bob,
>I have a LR3-14 voltage regulator hooked to a B&C alternator. It was set
>at the factory at 14.4 volts and for the last year it has been working
>good, except just recently it is only putting out 13.9 volts. Is this a
>heat factor or is my alternator wearing out? Should I adjust the voltage
>regulator back to 14.4 volts?
Try adjusting it upward. There might be something else
going on but adjusting is the first thing to try.
Bob . . .
--------------------------------------------
( Knowing about a thing is different than )
( understanding it. One can know a lot )
( and still understand nothing. )
( C.F. Kettering )
--------------------------------------------
Message 6
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| Subject: | Re: Grounding questions |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 09:53 AM 7/2/2003 -0400, you wrote:
>--> AeroElectric-List message posted by: DHPHKH@aol.com
>
><<The two batteries are in a common battery box and their negative terminals
> >are bolted together with a 1/4" bolt.>>
>
> Just a thought: May not be wise to bolt two heavy batteries
> together at
>the terminals. A flexible connection seems more appropriate.
>
>Dan
Good eye Dan! That one slipped by me. Battery terminals
are indeed poorly designed for structural loading. My
personal preference for battery connections is the very
pliable, welding cable like those offered at
http://www.aeroelectric.com/Catalog/wiring/wiring.html#sbl
and easily made at home.
Bob . . .
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