Mailing List lml@lancaironline.net Message #53400
From: Colyn Case at earthlink <colyncase@earthlink.net>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] L-IVP Battery Cooling
Date: Fri, 06 Nov 2009 07:36:31 -0500
To: <lml@lancair.net>
Clark,
    sounds like good stuff!
 
    I think Eric is right in general about the battery not being able to melt the wire but I suggest you look at the battery specs e.g. at odyssey and see how impressive their short term currents really are.  e.g. you can be over 200 amps for 30 secs going through a starter.  If you size it big enough, Eric is right.   If it's not big enough you could definitely melt it down.    If you get a dead short across the wires then it will be way higher current for way less time.  e.g. I think a odyssey pc680 will exceed 1000 amps for a few secs.
    In my airplane, all wires inside the cabin are attached to an ANL that will melt before the insulation on the wire does.  The only wires that aren't protected that way are from the battery to the grid and from the grid to the starter.
    If I were going to have batteries in the back I would probably put in one of those big 7" cooper bussman ultra slow blow fuses.   Then I would be able to let the smoke out after 90 seconds or so.
 
Colyn
 
 
----- Original Message -----
Sent: Friday, November 06, 2009 12:35 AM
Subject: [LML] L-IVP Battery Cooling

>>>Also, a remote location causes more voltage drop due to the longer cable.  I have one battery in the back and tried copper wire (very heavy) and had almost no voltage drop, but when I checked aluminum wires (very light), I had nearly 1.0v drop from the terminals to the Buss.  Aluminum is OK for avionics Buss, but not cranking or hydralic pump amp (too much heat and volt loss), if drawing off a battery behind the rear bulkhead.  My humble opinion.

<<My plan therefore is to make sure something else opens or fuses before the wire melts down.<<

I was curious about the statements above since I am using CCA (copper clad aluminum) battery wiring in my Legacy.  Below are comments from Eric Jones at Perihelion Designs.

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