Today's Message Index:
----------------------
1. 01:41 AM - Re: Battery Cranking Power (Good Info on wiring Battery/Starter!) ()
2. 06:57 AM - Re: Endurance Bus Voltage Measurement (Eric M. Jones)
3. 06:57 AM - Re: Battery Cranking Power (Mark Neubauer)
4. 06:58 AM - Lowrance 2000c (Mark Neubauer)
5. 01:55 PM - Alt/Batt switch question (Alan K. Adamson)
6. 02:09 PM - Denso Alternator Hook-up ('Peter Braswell')
7. 04:52 PM - Re: 5V regulated supply (Tim Olson)
8. 09:09 PM - Off, R, L, Both, Start switch (guy fulton)
9. 10:30 PM - Re: Denso Alternator Hook-up (Mickey Coggins)
Message 1
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| Subject: | Re: Battery Cranking Power (Good Info on wiring Battery/Starter!) |
--> AeroElectric-List message posted by: <gmcjetpilot@yahoo.com>
Dear David:
per Sky Tec's info, their PM starter current draw is approx 320 AMPS!
Reference this source: http://www.skytecair.com/Wiring_Experimental.pdf
This document has good info on wiring the starter.
Cheers George
From: "DAVID REEL" <dreel@cox.net>
Subject: AeroElectric-List: Battery Cranking Power
--> AeroElectric-List message posted by: "DAVID REEL" <dreel@cox.net>
I took some measurements today because my Panasonic LCRD1217P battery
cranking power seems marginal on cold, 45 degree, days with my O360A1A and
SkyTek permanent magnet starter. I saw 5.5 to 6.5v from the starter side of the
starter relay to a stud on the vacuum pad of the engine accessory case. I also
saw
5.5 to 6.5 v from the battery + terminal to airframe ground.
The battery was fully charged and measured 12.8v and was new. Assuming the
battery - terminal to airframe ground connection is good, it's new, and that about
200a
is being drawn by the starter, this gives a 25 milliohm internal battery resistance
to
explain the 6 volt drop on starting. The specs claim the battery has 12 milliohm
resistance at 77 degrees. Would the 30 degree temperature drop be enough to
reasonably explain this big increase in internal resistance? Could the starter
be
taking 400a? When the starter would stall, the battery voltage dropped to about
4.5v.
Dave Reel - RV8A
---------------------------------
Message 2
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| Subject: | Re: Endurance Bus Voltage Measurement |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
I ditto what JB says.
I also want to add that poking around with a mulimeter and trying to figure out
why there is voltage where you think there should not be, can be frustrating,
unnecessary and lead to Analysis-Paralysis.
All electronic circuits and their parts can be considered to have tiny add-on phantoms.
Every straight wire is a resistor, inductor, and capacitor plate, too.
Every diode has some leakage. All insulators have some conductivity. Young electronic
engineers have posters on their walls that remind them that "Ohm's Law
is Only a Crude Approximation".
So asking the question is the right thing to do; but even simple things can get
REAL complicated when one examines them too closely.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=24350#24350
Message 3
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| Subject: | Re: Battery Cranking Power |
--> AeroElectric-List message posted by: "Mark Neubauer" <markn@fuse.net>
Brian:
You have hit the problem on the head. A serious drawback to the SkyTec
starters is their very high current draw on each compression stroke. I
believe it is entirely possible that your starter is indeed drawing 400 amps
twice per engine revolution. It was for this reason, and using dual
Lightspeed III ignition systems, that I swapped my SkyTec over to a field
wound starter. They weigh more, but their cranking current is around half of
the series wound models. High current draw like this will pull the battery
voltage way down as you measured
As a footnote, I discussed this phenomenon with a representative from SkyTec
at Oshkosh in 2004. He could not have been more evasive and curt. I believe
his response to my query was something like "Cranking current is not our
concern, that is the airframe manufacturer's problem"
Mark Neubauer
Message 4
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--> AeroElectric-List message posted by: "Mark Neubauer" <markn@fuse.net>
I purchased a Lowrance 2000c last July and love it. It acts as the ultimate
back-up to my $9000 Garmin GNS-480, but I use the Lowrance most of time. It
doesn't have the screen resolution of the 296/396 series from Garmin, or the
cachet, but its display is bigger and it gets the job done very well for
about 1/3 the price. Also, think about this: the display on the Lowrance is
"portrait" format, whereas Garmin's is "landscape". Not sure why Garmin does
this, cause I'd much rather have more "screen" ahead of me than to the
sides.
Mark Neubauer
Message 5
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| Subject: | Alt/Batt switch question |
--> AeroElectric-List message posted by: "Alan K. Adamson" <aadamson@highrf.com>
Take Z14 for example. I know there has been lots of discussion about not
doing Avionics masters, but I have a somewhat related question.
I have an IO-550 with dual alt/batts. One alt will be a regular engine
driven one and it will be on the primary buss. The other, and SD-20, will
be on the essential buss.
So, in the scenario where I perform the initial startup, How does the VR and
the Backup alternator perform under this scenario.
A) I put the primary master in ALT+BATT.
B) I leave the CROSS TIE contactor OFF,
C) I put the Essential buss master to BATT only, not to ALT. I do this
because the engine instrumentation is on the essential buss and I want to
prime and watch for static fuel pressure, etc.
So, the primary battery provides all the power required for start and the
fuel pump (it's a Mag based engine). The backup battery is providing just
the power for the essential buss (in my case, the PFD EFIS, the AHRS, the
Magnetometer and the Engine instruments).
Once running, I switch the essential master to ALT and that should start the
backup alternator charging the system.
My real question is, is just having the ALT switch to the VR open, enough to
cause the alternator *not* to put out a charge until after I switch the
switch?
Perhaps I don't understand all the mechanics, but from the B&C datasheet on
the VR, (it's one of theirs), that is how you test it, so I figured, it
wouldn't hurt to start this way?
Would it be better to switch the cross tie on prior to switching on the
second alternator, or does *any* of this matter?
Thanks for reading and any replies.
Alan
Message 6
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| Subject: | Denso Alternator Hook-up |
--> AeroElectric-List message posted by: "'Peter Braswell'" <pbraswell@alterthought.com>
All,
I'm certain this is going to be a 101 question, forgive me.
I'm about to hookup my Denso alternator and it has two wires
protruding from the back, one labeled 'L' and the other labeled 'I'.
I'm certain one is for the "idiot light" and the other should be the
input for 12V and I'm no certain which is which. Any help would be greatly
appreciated!
-peter
Peter J. Braswell
CTO/CIO Canal Capital LLC
804.934.0300 ext 21
Message 7
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| Subject: | Re: 5V regulated supply |
--> AeroElectric-List message posted by: Tim Olson <Tim@MyRV10.com>
I wanted to post back to the list that I did get these parts
and have them working. I actually had to re-order as I accidently
ordered the ones listed below, and I needed NEF0100500B0. The other
ones were surface mount...didn't catch that quick enough.
The 5V DC-DC converters hold a solid 5V real well, it's a 10A unit,
and has multiple outputs. I have now flown and used it and it works
very good. I don't get the huge screeching nose I used to. I
do still get a slight alternator whine, so I'd be curious as to how
an isolated converter would be in comparison....I may order one
just to try it out. They were only $8.50, so it's a great deal
on a nice converter.
Tim
Tim Olson - RV-10 N104CD - Flying
Tim Olson wrote:
> --> AeroElectric-List message posted by: Tim Olson <Tim@MyRV10.com>
>
> Great tip Brian, I found them on Mouser, found a 10A version
> that will do what I need, for only $8.50. Bought
> 2 just because they were cheap. Should easily be able to
> do the job. I'll post back if it doesn't work. I bought
> the NEF0100500S0.
>
> Tim Olson - RV-10 N104CD - Flying
>
>
> Brian Lloyd wrote:
>> --> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
>>
>>> --> AeroElectric-List message posted by: Tim Olson <Tim@MyRV10.com>
>>>
>>> ...
>>> One of the players had an AC supply that says 5V@1A, and the
>>> other says 5V@2A, so I would have thought the 7805 had a
>>> fighting chance, but I guess that's with a heatsink or something.
>> Just for grins I did a search on Google. Seems that Mouser has several
>> that might work for you. Mouser is having a blow-out on discontinued C&D
>> switching DC-DC converters. Prices for a complete power supply capable
>> of delivering 25A at 5V are in the $10 range. There are also other
>> manufacturers.
>>
>> Give the time and effort needed to build something vs. just buy a
>> high-quality DC-DC converter, I think the answer is pretty clearly "buy".
>>
>> Give Mouser a call and tell them you need a 12V-in 5V-out supply that
>> can be isolated or non-isolated. You should be able to find something at
>> under $30.
>>
Message 8
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| Subject: | Off, R, L, Both, Start switch |
--> AeroElectric-List message posted by: guy fulton <truecolor32bit@yahoo.com>
-=Guy=-
I converted to Dual electronic ignition 2years ago,
now am doing a complete dash replacment. Now use a
series of toggle switches for each of the two ignition
systems. I wanted to use a standard aircraft ignition
switch but it works opposite of what is needed for
electronic ignition. Is there an aircraft switch
manufactured that would work with the electronic
ignition? Is there a modification I could make to a
standard switch that would work?
thanks for any help.
Message 9
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| Subject: | Re: Denso Alternator Hook-up |
--> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch>
> I'm about to hookup my Denso alternator and it has two wires
> protruding from the back, one labeled 'L' and the other labeled 'I'.
>
> I'm certain one is for the "idiot light" and the other should be the
> input for 12V and I'm no certain which is which. Any help would be greatly
> appreciated!
Peter,
The L connection would be for the warning light, and the I
would be for the ignition, that is, to start the alternator.
Here are some photos and more information about my denso
alternator - most of the information should apply to
yours, too.
http://www.rv8.ch/article.php?story=2004112513263691
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
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