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Moving a battery

 
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bferrell(at)123mail.net
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PostPosted: Sun Mar 23, 2008 6:08 am    Post subject: Moving a battery Reply with quote

Hello all,

We've just completed the second flight of our velocity
(http://www.youtube.com/watch?v=DpyMP7GkA-Y), and find that we really
are a bit more nose heavy than is really right, so if I want to carry
passengers I need to move my battery from the nose to back near the
firewall. So, I'm looking at my options, and want some input.

My current wiring diagram is here
http://www.velocityxl.com/Power/Power_Distribution.htm . Since it's a
pusher I already have a full-sized 2 gauge wire running the full length
of the airplane for the starter and the ground. My concern is around
the battery bus and the ground power, they currently connect directly to
the batter contactor's always-hot side with short runs. I don't really
want to move these bits, nor do I really want them on the switched-side
of the master. However, I'm not tickled with the idea of have a 20' run
of always hot 2ga wire either. I thought about putting a 200A ANL
current limiter on both ends, since you only *need* to protect the wire,
but who am I kidding, only 200A? That's not going to help sleep at
night knowing she's in the hangar like that.

So, it seems to me that my only *realistic* options are:
1) put the ground power in the back, and fuse the battery bus always-hot
at 30A (since it back-feeds the e-bus) with a new 8 gauge or so wire
2) put the ground power on the switched side, and require the master be
on to charge the battery (and fuse the battery bus always-hot at 30A,
same as #1)
3) ??

Any thoughts and/or suggestions greatly appreciated.

Brett


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nuckolls.bob(at)cox.net
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PostPosted: Sun Mar 23, 2008 1:19 pm    Post subject: Moving a battery Reply with quote

At 10:00 AM 3/23/2008 -0400, you wrote:

Quote:


Hello all,

We've just completed the second flight of our velocity
(http://www.youtube.com/watch?v=DpyMP7GkA-Y), and find that we really
are a bit more nose heavy than is really right, so if I want to carry
passengers I need to move my battery from the nose to back near the
firewall. So, I'm looking at my options, and want some input.

My current wiring diagram is here
http://www.velocityxl.com/Power/Power_Distribution.htm . Since it's a
pusher I already have a full-sized 2 gauge wire running the full length
of the airplane for the starter and the ground. My concern is around
the battery bus and the ground power, they currently connect directly to
the batter contactor's always-hot side with short runs. I don't really
want to move these bits, nor do I really want them on the switched-side
of the master. However, I'm not tickled with the idea of have a 20' run
of always hot 2ga wire either. I thought about putting a 200A ANL
current limiter on both ends, since you only *need* to protect the wire,
but who am I kidding, only 200A? That's not going to help sleep at
night knowing she's in the hangar like that.

So, it seems to me that my only *realistic* options are:
1) put the ground power in the back, and fuse the battery bus always-hot
at 30A (since it back-feeds the e-bus) with a new 8 gauge or so wire

That seems to be the best solution. Given that you have dual
alternators a-la Z-12, then perhaps an e-bus is overly redundant.
Just tie it right to the main bus.

If ground power moves aft, then your panel feeders for the main
bus and ground can probably drop to 4AWG and move the c.g. still
further aft. In fact, with the battery back next to the engine,
ALL the fat feeders can drop to 4AWG and recover some empty weight
too.

Bob . . .

----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------


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Eric M. Jones



Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

PostPosted: Mon Mar 24, 2008 5:23 am    Post subject: Re: Moving a battery Reply with quote

Whenever I hear, "Moving a Battery," my ears perk up. Stein sells the Perihelion Design Super-2-CCA that not only will remove some weight (It's lower weight per foot than copper 4 AWG but has a much lower resistance than silver 2 AWG). SteinAir sells it. Contact them.

I still sell the Super-4-CCA, but I will transfer it to Stein when my spool is empty.


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Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
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