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Old 25-03-2009, 13:52   #1
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Location of Shunt

We have five (5) 12V 100A batteries wired in parallel. This "bank" is completely separate from our "wet cell" engine and house battery bank. Battery #1 is wired to the windlass and an inverter and is in parallel with battery #2.
Battery #2 is in parallel with battery #'s 1 and 3
Battery #3 is in parallel with battery #'s 2 and 4
Battery #4 is wired into our refrig. compressor and 260 watts of solar input.
Battery #5 is in parallel with battery #4.
When necessary (hardly ever) we charge this bank with a 2kw gas gen set. We bought a link 10 battey monitor for the bank. Where should we put the shunt?
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Old 25-03-2009, 14:38   #2
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Kind of confusing

Rather than wiring different loads to different batterys within the house bank a more common practice if to have one positive tap with all loads connected. Usually a BlueSea power post or one of their hi amp buss bars is used.

You should have a similar "single point" for the house ground. The shunt should be placed between the house bank and the common ground. For the shunt to work properly all neg. loads should be placed after the shunt.

A good discussion of shunt wiring is at Another Xantrex installation question?
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Old 25-03-2009, 14:42   #3
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I am not sure of the reason for your wiring in parallel and then tapping different batts for separate loads.

If you are using a monitor when you parallel batts the monitor will see them as one large battery.

The shut is placed in between the neg terminal of the last battery in the parallel bank and the neg buss which all neg returns are connected too.

This read the state of discharge of the entire bank.
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Old 25-03-2009, 16:58   #4
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further clarification

Use a positive and negative distribution post(s). Imagine all of the batteries lined up either parallel or end-to-end. If you "daisy-chain all of the negative cable interconnects and daisy-chain all of the positive ones then you pick one "end" of the chain to lead the last positive battery cable to the positive distribution post. You then pick the OPPOSITE end of the battery negative chain and lead that to the shunt. From the shunt you wire to the negative distribution post. Make all of the interconnects between batteries the same length. Make both leads between the last (and first) batteries to the distribution post the same length (the length of cable to the positive distribution post must equal the combined lengths of the cable to the shunt and from the shunt to the post.

This creates equal current sourcing and charge current acceptance between all the equivalent batteries in the bank. Make sure that NO OTHER wires ("sneaker-wires") attach to the individual batteries in the bank. All other wires connect to the distribution posts (except the Link 10 ones, of course)
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Old 25-03-2009, 17:47   #5
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Is this a part of the new math?
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Old 25-03-2009, 18:53   #6
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Quote:
Originally Posted by bobelon View Post
We have five (5) 12V 100A batteries wired in parallel. This "bank" is completely separate from our "wet cell" engine and house battery bank. Battery #1 is wired to the windlass and an inverter and is in parallel with battery #2.
Battery #2 is in parallel with battery #'s 1 and 3
Battery #3 is in parallel with battery #'s 2 and 4
Battery #4 is wired into our refrig. compressor and 260 watts of solar input.
Battery #5 is in parallel with battery #4.
When necessary (hardly ever) we charge this bank with a 2kw gas gen set. We bought a link 10 battey monitor for the bank. Where should we put the shunt?
That is a weird way to wire any battery bank.
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Old 26-03-2009, 11:34   #7
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Yes weird sez it all. It was done for the sake of convience but if we want to use the link 10 we will have to rewire the bank using the suggestion of Rick. This may not be possible tho since the windlass battery is 25 feet away from the other four batteries. Will see, gotta think this one thru.
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Old 26-03-2009, 19:23   #8
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Windlass battery

Weigh the windlass battery. Calculate just how much two cables weigh for the distance from your proposed positive and negative distribution posts that will carry the peak current for the windass without much voltage drop (say 5%). You might be surprised that the cables will weigh less or equal. If equal the weight distribution of the cables will be way better than the pitching moment mass that a windlass battery adds to your boat.

In general it is better to not have a windlass battery.
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Old 27-03-2009, 03:43   #9
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Placing a dedicated windlass battery forward, near the windlass, doesn’t eliminate the need for large supply conductors - it merely reduces the size somewhat. Depending upon the size of the battery, you will want the cables to be sized for a maximum voltage drop of 5% at a minimum of 25% of the battery Amp-Hour capacity (larger would be better).
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Old 27-03-2009, 13:11   #10
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It's gonna take me a some time to digest these last two posts but anyway the cat's out of the bag and we already have the 5 batteries installed linking the 4 in the aft with the forward battery with #2 cable about 20 ft. See what happened was that a mega yacht took out these 5 agm's and replaced them because they were about a year old. Anyway they sat on the dock at my boat for about a month and when I put a voltmeter on them they all read about 13.1V plus or minus a tenth. What the hell I just couldn't help myself. This is why we have two banks of batteries which cannot be linked cuz the house and starter batteries are wets. These 5 agm's are in parallel but only supply power for refrigeration, a 110 converter and the windlass. There is no common ground. There was no room for the 5th battery in the aft of the boat, as you can imagine.
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