X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: Date: Fri, 06 Nov 2009 00:35:11 -0500 Message-ID: X-Original-Return-Path: Received: from elasmtp-banded.atl.sa.earthlink.net ([209.86.89.70] verified) by logan.com (CommuniGate Pro SMTP 5.3c1) with ESMTP id 3950443 for lml@lancaironline.net; Thu, 05 Nov 2009 22:20:37 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.70; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=ATPZPfgO1RLUmtPlIsh5HLqzX5VLWulVNMgmxfrRhGKBpO4XVzvwy4ka2q3dVPhK; h=Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-ELNK-Trace:X-Originating-IP; Received: from [216.57.118.33] (helo=ccaselt3) by elasmtp-banded.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1N6FMo-0006JS-JB for lml@lancaironline.net; Thu, 05 Nov 2009 22:20:02 -0500 X-Original-Message-ID: <00af01ca5e90$0762af90$e48c020a@nvidia.com> From: "Colyn Case at earthlink" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: L-IVP Battery Cooling X-Original-Date: Thu, 5 Nov 2009 22:20:02 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00AC_01CA5E66.1E451740" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3598 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3350 X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940057f430ae08d3ff0e86f7078bca0eced350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 216.57.118.33 This is a multi-part message in MIME format. ------=_NextPart_000_00AC_01CA5E66.1E451740 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Re: L-IVP Battery CoolingBill said, I may be missing something but I = don't understand how a fuse between the cable and the power buss(es) = would provide protection. In a rear mount installation, it would be hard to protect the long wires = during starter operation. However, assuming a front mounted power grid, you could limit the amount of current the long wires see in flight by = inserting a fuse between the long wires and e.g. the battery bus bar = that feeds the airplane in flight. My goal was simply to protect the installed wire. My strategy was = fairly simple: 1) for each bus figure out what max continuous load is 2) size the main feed wire based on a continuous rating of that load 3) size the anl on that bus to blow at the current for which that wire = is rated for the 2-minute limit So for example, if you wanted 70A capacity on your main bus you would = pick at least a #8 wire. The #8 wire has a 2-minute rating of 90A. A 40A ANL will blow after = about 30 secs at about 90A but will run forever at 70A. A 40A anl will also tolerate about 130A for 5 secs, enough to get your = hydr pump started. The anl's are mostly mounted on the side of the battery box, easily = inspectable and away from passenger activity. One test for reasonableness is "What is the probability of this = happening?" Another test, and I think a more meaningful one is "What is the worst = damage that could occur if this thing does happen?" I had a friend fill a new T210 with smoke because of a misbehaving = battery in the back. IMC. He had to shut down all electrics. = Fortunately for him, all the relays opened and his AI was vacuum driven. I had my own Nissan Stanza fry its entire wire harness and burn a hole = through the fender. Nothing stopped it until we ripped the terminal = off the battery. That was a serious amount of smoke! I'm sure both of these designs passed rigorous design reviews and in = both cases what actually happened was a low probability event. The problem with low probability events is that when they are happening = to you, they are 100% happening to you. Colyn ------=_NextPart_000_00AC_01CA5E66.1E451740 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Re: L-IVP Battery Cooling
Bill said,   I may = be missing=20 something but I don't understand how a fuse between the cable and = the power=20 buss(es) would provide protection.
 
In a rear mount installation, it would = be hard to=20 protect the long wires during starter operation.  However, assuming = a front=20 mounted power grid,
you could limit the amount of current = the long=20 wires see in flight by inserting a fuse between the long wires and e.g. = the=20 battery  bus bar that
feeds the airplane in = flight.
 
My goal was simply to protect the = installed=20 wire.   My strategy was fairly simple:
1) for each bus=20 figure out what max continuous load is
2) size the main feed wire based on a = continuous=20 rating of that load
3) size the anl on that bus to = blow at the=20 current for which that wire is rated for the 2-minute limit
 
So for example, if you wanted 70A = capacity on your=20 main bus you would pick at least a #8 wire.
The #8 wire has a 2-minute rating of = 90A.  A=20 40A ANL will blow after about 30 secs at about 90A but will run forever = at=20 70A.
A 40A anl will also tolerate about 130A = for 5 secs,=20 enough to get your hydr pump started.
 
The anl's are mostly mounted on the = side of the=20 battery box, easily inspectable and away from passenger = activity.
 
One test for reasonableness is "What is = the=20 probability of this happening?"
Another test, and I think a more = meaningful one is=20 "What is the worst damage that could occur if this thing does=20 happen?"
 
I had a friend fill a new T210 with = smoke because=20 of a misbehaving battery in the back.   IMC.  He had to = shut down=20 all electrics.  Fortunately for him, all the relays opened and his = AI was=20 vacuum driven.
 
I had my own Nissan Stanza fry its = entire wire=20 harness and burn a hole through the fender.   Nothing stopped = it until=20 we ripped the terminal off the battery.  That was a serious amount = of=20 smoke!
 
I'm sure both of these designs passed = rigorous=20 design reviews and in both cases what actually happened was a low = probability=20 event.
The problem with low probability events = is that=20 when they are happening to you, they are 100% happening to = you.
 
Colyn
 
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