Date: Sat, 27 Dec 2008 20:58:37 -0800
Reply-To: M'obeechi <obeechi@RUNBOX.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: M'obeechi <obeechi@RUNBOX.COM>
Subject: Voltage Drop - Less than 3% - 15 feet, 2/0, 150 Amps is on target
In-Reply-To: <20081228023516.140B71165C3@hamburg.alientech.net>
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http://genuinedealz.com/voltage-drop.html
Using the above, and the knowledge that stock battery for a 2.1 was 2/0 (pronounced 2-aught, don't ask me why... )... and running the wire forward from my Subaru Legacy 2.2 starter through the two holes under the van (which line up with the two holes above for the stock rear heater water hoses), then running under the van still, to the driver side, then up through the van's floor (an inch or two left and rear of the stock wires that pop up here (I assume they're stock, and not conversion related...I don't mean the wire harness, but the wires coming up through the floor board under the rear seat) then running (now inside the van) all the way to the driver side interior wall, then forward from to the front (while running alongside the bottom of the driver side wall, tucked in the wall's bottom edge (with the cork, most likely trimmed...) then turned to the middle, and finally turned upward immediately after the center console's driver side boundary, and connected to a Battery Selector 3/4 stud (a Bluesea HD gray Battery Selector, mounted vertically in a wood wall 18 inches tall (same effective height as the Center Console Terry K sells, when placed in the between the front seats) (the driver can reach back with right his hand and select a battery while driving [and the passenger is blocked by the center console {if you own one}, because you don't want anyone turning it to OFF while the engine is running {can ruin the alternator, though WestMarine sells something to mitigate this }] ...
Well, long story short, this requires 12 feet to connect to the battery selector, and then another foot to connect to Battery 1 behind the driver seat, and another two feet (from the Selector) is required to connect to Battery 2 behind the passenger seat... so assuming 15 feet (to allow for bends et, which I've already tried to incorporate -- I used a rope to measure this), and then
Plugging in to web link (listed at top) the values of 15 feet, 12 volts, 2/0 AWG, Copper Wire... puts the voltage drop right at 3.0 %, exactly... when assuming 150 amps... which is more than the stock 2.1 of 65 amps, as well as more than the 70 amps of the subaru legacy stock alternator, or even a high amp alternator rated at 135 amps for a 1990-1994 Subaru Legacy, or a 140 High Amp Alternator for a 1995-1999 Subaru Legacy, though admittedly less than a 160 High Amp Alternator for an SVX... (the voltage drop is 3.2 % for the high amp SVX alternator... )
The moral of this story is that.. with the exception of a the SVX... 2/0 wire is more than sufficient even for a battery setup which extends the battery wire length to beyond-stock-original-length (and note here, the driver side Starting Battery is really seeing only a 13 foot length which in the case of the 160 Amp SVX High Amp Alternator, is a voltage drop of only 2.78 % [or, Battery B, sees only an actually length of 14 feet, with a voltage drop of 2.99 %]... so really, this 2/0 wire length is okay for even the SVX powered Vanagon, I'm just over-speccing it a bit, for extensibility, et).
The nice thing about this is, WestMarine keeps 2/0 wire (made by Ancor) on hand, in reels, and so the 2/0 wire can be cut it to any length... and you're not stuck special ordering 25, or a 100, feet at a time... and WestMarine's wire, being marine rated tinned copper of type 3, with an AWG rating instead of an SAE gauge rating, is better than standard automotive wire...
But..., its still 225 dollars worth of wire... at 15 dollars per foot... not including the extra foot or half foot per length that one might get to insure they're not cutting themselves short... (personally, I'd buy each length already cut, and give each cut extra bit of length.., instead of buying the whole length).
Quote [from WestMarine's Website]:
Ordinary automotive-type wire can suffer a loss of conductivity after a few months in the marine environment, caused by corrosion and/or vibration. Premium Ancor wire will provide a lasting solution for your sophisticated marine electronics and instruments to operate at peak potential.
600V
105°C dry, 75°C wet
Rated for oily and wet environments
Wire has a tin coating for extra corrosion resistance
Type 3 stranded, with 5–10 times more copper strands than Type 2
Marine UL-listed, and meets the highest ABYC standards for AC or DC use
Based on AWG (American Wire Gauge) wire sizes, 6–12% larger than SAE gauge wire
Note: Oh, the Web link assumed AWG, and this is what Ancor is rated with... so no conflict here...
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