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Old 08-01-2011, 07:06   #1
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BMV-600 Installation Question

Hey Everyone!

I recently purchased a BMV-600 single bank monitor for my Beneteau 343 sailboat. Upon getting started with my installation, I noticed that my boats wiring is a bit different that what could be expected in the installation manual provided by Victron.

First, some background. My boat has 2 battery banks, however I am only concerned with monitoring my house bank. The 2 banks are all populated with Group 27 flooded batteries. The starting bank is a single Group 27 battery. The house bank, however, has 2 Group 27's wired in parallel.

The positive posts of each battery bank is wired to its own separate positive switch....meaning, if I wanted to shut off/isolate the starting bank, I would simply turn off the positive switch for that bank. However, for the negative side of things, both banks are wired to a common negative switch. Meaning, if I wanted to shut off the entire electrical system to the boat, I would simply throw the switch for the negative bank. All this is standard I'd imagine for many boats.

Here's where I'm a bit confused. On the negative switch, all of my battery cables seem to be crimped together onto a single lug which is then then attached to the negative switch. I'd imagine Beneteau did this to save some bucks of having to crimp seperate connectors for everything that needs to attach to the the negative switch and keep things cleaner. See this picture for the visual (sorry for quality...cameraphone):

As I would like to install and monitor only the house bank, I am wondering if I can simply take that common, crimped cable and attach it to one end of the shunt of the monitor. Then have another battery cable fabricated and take it from the other side of the shunt and attach it to the common negative switch. OR, since I only want to monitor the house, would I be required to uncrimp the cables and separate the house bank negative cable and ONLY attach the house bank negative cable to the shunt and place all the rest directly on the negative switch?

I want to desperately to get this project done this weekend and cant wait for Victron support to be back online on Monday. Please help!

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Old 08-01-2011, 07:29   #2
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I like the separate switches on the positive cables for each battery bank (assume they're simple ON/OFF switches), but I sure don't like the idea of grouping the negative cables together into a single lug going to the negative switch.

The "right" way to do this would be to install a negative bus, and connect each individual wire to that bus. You could then put the Victron shunt on the battery cable from your house bank between the bus and the batteries.

With the right tools, this shouldn't take more than 30 minutes or so to do, and you'd have a much neater and, to my mind, "better" setup which would do what you want to do.


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Old 08-01-2011, 07:52   #3
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Bill, I agree that a bus bar, with each cable connected individually, is the way to go. It will be neater, more reliable and easier to troubleshoot or upgrade in the future. The shunt can then be placed in the cable that carries the current you're actually interested in measuring.

If you put the shunt between the common negative switch and that ugly mess of a terminal lug (no offence), the instrument will measure both banks when they're both in use, and the house bank only when the starter is disconnected- but it'll have no way to know when you switch between them, so I'd be reluctant to trust its readings.
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Old 08-01-2011, 12:48   #4
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Ok - thanks for the advice group. I will definitely invest in a negative bus bar and then clean up all the wiring. In the interim, however, here is what I did.

1) Bought two feet of 2/0 black battery wire
2) Bought three battery crimps 2/0 size
3) Bought heatshrink]
4) Bought some 5200
5) Bought box of stainless steel wood screws
6) Bought 2 stainless large wood screws

I cut the existing cable for the house bank behind the crimp and taped off the remaining stub of the old cable with heatshrink and electrical tape. I then crimped on one of the battery connetors onto the old battery cable and applied the heatshrink. I think fabricated my battery cable out of the 2 ft 2/0 gauge wire and remaining crimps and heat shrink.

I then mounted the shunt onto a block of mdf using the large wood screws (fender washers wouldn't fit...need to find smaller ones) and then used 5200 to mount that block to the wood in the battery locker, then connected everything up per instructions. The old house negative cable with new crimp to the one side of the shunt and the new fabricated cable from the shunt to the common negative. As it stands, the rj cable is still going across my sole...need a second pair of hands to help fish it through the cable chases, but I have my handy-dandy fish tape ready to go!

I then dry fit everything up, and it looks like I'm in business!

Two more projects have come from this project. First, I need to install that negative bus bar and clean up all the cables that are on the shared common negative. What a mess. Beneteau has done a spectacular job with the wiring elsewhere, but this just is worthy of a beat down.

Second, I have a voltage leak somewhere (as I long suspected). With everything turned off, I still track -0.25 to -0.5 amps somewhere. That seems to be a lot of stray

Lessons learned...a 2 hour project will inevitable take 7. Also, make sure you have a vacuum handy when you use a hole saw to drill through the wood...I forgot to have something catch the savings/sawdust...what a mess Lastly...if you want to do something right, it takes tiiiiiime.

I wanted to install the bilge counter today too..but *sigh* I guess it will wait for another day.
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Old 08-01-2011, 12:53   #5
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nightOwl, Before you drive yourself crazy that voltage is probably coming from an LED somewhere including those LED lights on your panel. Chuck
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Old 08-01-2011, 13:33   #6
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Originally Posted by Waterwayguy View Post
nightOwl, Before you drive yourself crazy that voltage is probably coming from an LED somewhere including those LED lights on your panel. Chuck
Hmm, need to verify but I *think* I took that reading with EVERYTHING killed via throwing the negative switch to off. My panel does have a big ol' led thats the backlight for the analog voltage meter there. Useless. I should just clip the wires on it. Lemme check.
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Old 08-01-2011, 13:48   #7
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Nope, something definitely is not right. With the entire system shut down and only the bilge pump directly wired to the batteries, the monitor took this reading:

Is a 1/10th of an amp something I need to worry about?
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Old 08-01-2011, 14:06   #8
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Yes mine reads 0.00 when nothing's on. I just got one on my 393 as my Link crapped out. Much prefer it to the Link.
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Old 08-01-2011, 14:35   #9
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I'm surprised bene ran that many wires to one post. Doesn't abyc require no more than 3 lugs per post?

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