Date:         Mon, 29 Dec 2008 02:35:00 -0800
Reply-To:     M'obeechi <obeechi@RUNBOX.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         M'obeechi <obeechi@RUNBOX.COM>
Subject:      Re: Voltage Drop - Less than 3% - 15 feet, 2/0,
              150 Amps is on target
Comments: To: mdrillock@cox.net
In-Reply-To:  <49578AAC.3060001@cox.net>
Content-Type: text/plain; charset="iso-8859-15"

Well, I've narrowed down my battery scheme to just two batteries, a large starting battery, and a large house battery. While currently wet Interstates, I'm going to change over to two Group 31 Platinum's from Sears which have 1150 cranking amps and are 100 amp hours. There is going to be a Bluesea BatteryLink Relay between them with a manual switch, so I can either leave it on automatic (for joining and disjoining) or manually switch the relay on or off. Besides limiting current with not-fat wire, I can choose to switch the relay off while city driving, and set it to automatic while freeway driving. Don't think I'd ever use the manual "on"... In addition I have a 135 watt Kyocera Solar Panel (installed to the roof of my Carat so far, but not yet connected electrically), which will charge the house battery primarily but also send auxiliary current to my starting battery of 2 amps or less. 

I'm feeling pretty good about it right now.... have the batteries secured behind the front seats at this point... but if you see a weakness, let me know... 

Thanks for the Genuine tip... 

From: mdrillock <mdrillock@cox.net>
To: M'obeechi <obeechi@RUNBOX.COM>
Subject: Re: Voltage Drop - Less than 3% - 15 feet, 2/0, 150 Amps is on target

> Genuine Deals sells that 2/0 marine grade wire for only $5 a foot 
> including shipping. I have bought a lot of wire from them for Vanagon 
> projects, though nothing close to 2/0.
> 
> http://shop.genuinedealz.com/Items/Item.aspx?SKU=gim-wul2/0rd-/ft&caSKU=gim-wul2/0rd-/ft&caTitle=2/0%20AWG%20Tinned%20Marine%20Battery%20Cable%20Boat%20Wire%20RED%20/ft
> 
> The reason to use such heavy wire between the starter and starting 
> battery is for high starting current more than for charging current.
> The stock Bosch WBX alternator is rated 90 amp not 65amp.
> 
> If you connect multiple large batteries to the alternator with such 
> large wire you might want to find a place to buy replacement alternators 
> in quantity.
> 
> Mark
> 
> 
> 
> M'obeechi wrote:
> > http://genuinedealz.com/voltage-drop.html
> > ..............
> > 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). 
> > ...............
> >
> > 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).
> >
> > ..................
> 

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