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Wiring & Installing A Battery Monitor

May 24, 2004
470
Hunter 33.5 Portsmouth, RI
MS, I think you had s small senior moment (you don't have many). 3 meters is 9.84 Ft. (3.
28 Ft. per meter).
 
Nov 8, 2010
11,048
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
How far can I place my battery monitor from the batteries and what size wiring is needed if the monitor is a more than three feet from the batteries?
There should be no practical limit on how far the head unit is from the batteries (actually: how far from the shunt), except for the length of the cable you have to connect them. Shunt placement however is more important, should be logically placed between the battery and the Negative buss.
 
Feb 6, 1998
11,272
Canadian Sailcraft 36T Casco Bay, ME
If I understand correctly a good place to wire the "load side" would be the negative
terminal on the alternator. Correct ? thaeni@comcast.net
Huh? The negative terminal of the alternator, if you have one, should lead to your ships negative ground buss or to the load side of the shunt just as every other load does.

Look at the pic above with the green writing where it says -LOADS YES. Your alternator negative wire would attach to any of those spots with the green line pointing to it. You wiring may not resemble that but the alt MUST be connected on the load side of the shunt NOT the battery side..


Many boats are poorly wired and the DC neg buss may need to be cleaned up or you may need to add one. If you are using a NASA monitor make sure your house bank is not more than 600 Ah. The last time I looked at one they were only designed to handle banks to 600 Ah which is a fairly medium size these days.
 

asaila

.
Jan 10, 2011
1
Catalina 34 mkII Ottawa
Thanks for such a comprehensive post.

I installed a Victron unit last year on my Catalina 34 mkII. I used the two-battery version.
The batteries are two 185 a/h Rolls/Surrette, configured on the standard A/B switch, 4 years old. They are charged with a Xantrex tru-charge 2 40amp charger.

It seemed to work fine (all displays work exactly as expected, when charging, consuming power etc.) for a few weeks, but I came back to the boat after a two week absence to find the batteries run down to 10.5 V, but with minimal power consumption displayed (maybe 5 amp/hours). The A/B switch was off.

After a couple more experiments that showed the batteries seemingly unable to hold a charge, I disconnected the red wires from the shunt, and left the boat again. No problems this time. The batteries held their charge with minimal loss.

So my conclusion is that something in what I have done is causing energy to be consumed that is not being displayed on the Victron monitor, and is running down the battery. When I remove the red wires, but make no other changes to the wiring, this stops.

I would like to use the monitor, but not at the expense of running down the batteries. Any ideas? Do I have a defective monitor?
 
Feb 8, 2009
117
Sabre 34 MK-1 Annapolis, MD
Solution for 2 banks

The AH portion of the meter uses the shunt as the sole data input. The power wire provides power to run the unit, as well as an input for the V display. There is no real requirement that the power come from the same battery that you are monitoring.

A solution to checking the voltage of a second bank could be this. Run the red wire from the shunt to a SPDT toggle switch. From the switch, run wires to each battery positive (fused, of course). The switch would then allow you to select the battery that the "V" is reporting.

Three possible downsides:
* It's a nuisance if the switch isn't convenient
* You forget you set it to "Start" and cheerfully see that your nearly dead house bank is still at 12.5V
* When the switch is flipped, there will be a brief "off" period. If the battery monitor doesn't have static memory, it would instantly forget everything it knows -- including your current SOC. This would have to be verified before setting this up!

Harry
 
Oct 26, 2008
4,478
Catalina 320 Barnegat, NJ
This is a great reference post! I could have used it last summer when I installed a Link Pro (it took me at least a year after purchasing it to get my head wrapped around the installation!). I found the instruction sheets very limited in explanation, lacking in content, and confusing to say the least! Actually, I'm still not done since I have to re-wire the alternator direct to the house bank anyway. I think I will add the pos & neg buss bars since those misc. leads are connected to the batt posts as it stands now.

Doing this project also clued me into the need for fuses. I added MRBF fuses for the start and house banks. The price of the Link Pro was significant ... especially after purchasing all the wiring and fuses involved! I found very little help from the manual in organizing and planning the whole wiring set-up.

Sadly, I think that my batts are never fully charged since I'm on a mooring and charge by alternator only. This spring's commissioning will involve a solar charger, I think.
 
Feb 26, 2004
21,222
Catalina 34 224 Maple Bay, BC, Canada
Scott, sorry it took you so long. I know how you feel, I waited like eight years or so (!) before I installed my Link 2000, and I'm an engineer!!!

You might be interested in this, I've posted it many times before: http://c34.org/bbs/index.php/topic,4922.0.html

One of the ideas we learned was for anyone unclear on the functions of the newer Link series is to download the old Link 2000 manual which has MUCH better installation, algorithm and use instructions. Silly, but the newer units documentation is quite poor. Dunno about the Victron, but with this tutorial from Maine Sail, instructions should be easier to follow.

You'll also find that you've been mistreating your house bank and your solar idea is a wise one.
 

Nodak7

.
Sep 28, 2008
1,126
Hunter 41DS Punta Gorda, FL
Install a Xantrex on the boat before the season started last year and it worked great! Very helpful and informative. Very nice to get an instant condition of the battery without just guessing. It is also helpful to spot how much load each device is drawing. I would not have a boat without one any longer.
 

MSter

.
Apr 12, 2010
131
Sabre 38' MK II Oriental, NC
Maine Sail,
Another terrific posting and one I will want to save for future use. You must spend a lot of time answering questions from new & inexperienced sailors such as myself because you answered all of my questions in your next paragraph !
Truly amazing how you read my mind !
Thanks for your many great contributions.
Mster
 
Feb 26, 2004
21,222
Catalina 34 224 Maple Bay, BC, Canada
Install a Xantrex on the boat before the season started last year and it worked great! Very helpful and informative. Very nice to get an instant condition of the battery without just guessing. It is also helpful to spot how much load each device is drawing. I would not have a boat without one any longer.
Nodak,

The REAL beauty of these widgets is that they tell you how much you PUT BACK INTO your house bank. I think over the years what comes OUT has been well documented. As we've noted before, battery acceptance considerably affects how long it takes to return amps to the bank.

That's what I've found most useful about them and should go a long way for all of us to be able to take better care of our batteries and save replacement $$. Good battery monitors are almost an instant ROI payback: think of what even two inexpensive batteries cost and if you add two years of life to them you've bought a Victron for free! :)
 
Jan 10, 2011
2
Jeanneau Sunshine 36 Santa Barbara
Maine Sail:

Thank you for the wonderfully documented article. Very nice!

On the starting battery, I already have an ultra-simple and remarkably cheap battery monitor (the $37 Battery Bug by Targus). For the house bank, I have wanted to set up something like what you have shown. However, I have been puzzled about how well these devices work on banks of dissimilar batteries.

In this case, I have three batteries in parallel in my house bank. They are all deep cycle flooded batteries, but not the same size or Ah. From memory, one is 90 Ah, and the two others are 120 Ah. Are battery monitors effective in such a setting, and how do you wire them?

Thank you once more.

Yann
French Cut, Sunshine 36
Santa Barbara
 
Feb 26, 2004
21,222
Catalina 34 224 Maple Bay, BC, Canada
In this case, I have three batteries in parallel in my house bank. They are all deep cycle flooded batteries, but not the same size or Ah. From memory, one is 90 Ah, and the two others are 120 Ah. Are battery monitors effective in such a setting, and how do you wire them?
Yann,
As they're already wired parallel for a house bank, consider the bank just one big battery. The monitors are wired just as Maine Sail describes. One positive and one negative out from the three battery bank. You have a nice 350 ah bank. You monitor the "bank" not the individual batteries.

And it's a perfect application for monitors.
 
Feb 6, 1998
11,272
Canadian Sailcraft 36T Casco Bay, ME
In this case, I have three batteries in parallel in my house bank. They are all deep cycle flooded batteries, but not the same size or Ah. From memory, one is 90 Ah, and the two others are 120 Ah. Are battery monitors effective in such a setting, and how do you wire them?
As Stu said it will work fine but your bank is not really the ideal situation as far banks go. To program the monitor simply add up the Ah ratings of the parallel batteries and plug them into the monitor.

In a perfect world you want batteries that are combined into a bank to be of the same, size, type, age, preferably LOT# / date code and brand.

All deep cycle batteries are not created equal and there can be variations between even a group 27 & 31 of the same brand in plate thicknesses, plate make up etc. etc.. Keep what you have until it dies but on the next round you will probably get a longer life out of batteries of all the same model, age and type.

As always when you parallel banks the positive and negative load wires should come off opposite ends of the bank for the best charging and discharge.

Notice the connections to the battery coming from opposite sides...
 
Jan 10, 2011
2
Jeanneau Sunshine 36 Santa Barbara
Stu:
Maine Sail:

Thank you for the discussion of the multi-battery bank. This is information I had been unable to find in the manufacturer's user guides or Wing's Electrical Handbook. Terrific!

Yann
 

Mike B

.
Apr 15, 2007
1,013
Beneteau 43 Baltimore, MD
Maine Sail one of your pictures shows a fused buss coming off the battery POS terminal. I'm looking for one for my house bank but cant seem to find one. Is this a custom or off the shelf part?
Thanks
Mike
 
Feb 6, 1998
11,272
Canadian Sailcraft 36T Casco Bay, ME
Maine Sail one of your pictures shows a fused buss coming off the battery POS terminal. I'm looking for one for my house bank but cant seem to find one. Is this a custom or off the shelf part?
Thanks
Mike

Mike,

Those fuses are called Marine Rated Battery Fuses or MRBF's. They're made by Blue Sea Systems and come in both a single fuse holder, and a double, with fuses ranging in size from 30A to 300A. SailboatOwners.com carries them!!

SBO MRBF Fuses (LINK)

Blue Seas MRBF Terminal Block (LINK)

Blue Seas MRBF Fuses (LINK)


They can also be used nicely on buss bars provided you use terminal caps and buss bar protection covers.

 

Mike B

.
Apr 15, 2007
1,013
Beneteau 43 Baltimore, MD
Maine Sail this is perfect. I'll be picking one up for spring installation. Thanks for the help!
Mike