Wiring in a battery electrical display unit

[Rick]

Need some help from the electrical experts. I bought a Clipper electrical display monitor. I displays current battery state, amp draw, time to charge, and starter voltage if desired. I was playing around with it and hooked it up to my 4 6volt house batteries that are wired in series parallel. I hooked it up upstream from the trace inverter.

Basic wiring involves a shunt (supplied) and cable (supplied). The negative lead from the bank goes to one side of the shunt, and the cable(supplied) goes to the negative terminal. The supply wires are on either side of the shunt that feed the display.

So I hooked it up and couldnt get it to read anything accurately (with voltmeter as my standard) except volts. Amp draw was inaccurate. So with defeat in hand I decided to hook it up to the starter bank. I isolated one of the 12 volters and hooked it up as prescribed in the manual. It worked perfectly, again backed up with voltmeter.

My setup is two perko's which give me the power to run house on first perko with either engine or house bank, and then the second perko will start engine off either starter bank or house bank.

So my question, wrong place to wire it in. Im thinking I need to find the negative ground for the boat from the battery, which is on a bus right near the front of the engine.

Maine Sail... et all, A starting point for where to hook this thing in. It perportedly will monitor up to five banks. I need to find the master negative terminal/shunt on the boat? And not sure if that is even the correct terminology.

For an example if you look at the Vectron technology site, you can find the battery monitor. It is very similar. I wanted to be able to see my amp draw which I currently cant do.

Thanks gents and gals.

 

[Maine Sail]

Rick,

You need to make sure that there are NO other negative wires are getting back to the bank by NOT going through the shunt first. All system negative wires must be on the system side of the shunt and NOT the battery side. If you have negative leads that bypass the shunt they will NOT be read if they are on the battery side of it.

This includes chargers, solar panels or alternators. All negative leads must be processed through the shunt..

People often forget that their charger may be direct grounded to the battery and they forget to remove it and put it down stream of the shunt.

The best way to isolate all the negative leads is to use a ground buss bar and all grounds run to that. Then one wire goes from the negative buss to the shunt. There should be NO negative wires attached direct to the battery except for the other battery negative wires for parallel or series/parallel and the shunt jumper...

 

[Rick]

Thank you Maine Sail. I am actually on the boat for a couple of days. I will attempt to find the correct master buss bar and go from there. Im fairly handy with electrical but certainly not an electrician. Finding the correct buss will be my challenge. Could it be behind the electrical panel? Or perhaps the one I found down in the engine compartment? Obviously i will use care to make sure I take safety precautions when looking behind the electrical panel.

Also when you said "system wires" did you mean the approximately 16 guage wires that get the information and run to the display? Or do you mean various boat system wires?

Will update

 

[Maine Sail]

Thank you Maine Sail. I am actually on the boat for a couple of days. I will attempt to find the correct master buss bar and go from there. Im fairly handy with electrical but certainly not an electrician. Finding the correct buss will be my challenge. Could it be behind the electrical panel? Or perhaps the one I found down in the engine compartment? Obviously i will use care to make sure I take safety precautions when looking behind the electrical panel.

You may not have a ground buss other than the one for the small gauge hose loads, 12 ga 14ga etc.. A ground buss bar can be easily added to clean up the the negative connections. All negative leads eventually lead back to the ground buss and the ground buss is connected to the battery and then the buss to the engine earth as earth ground.

Also when you said "system wires" did you mean the approximately 16 guage wires that get the information and run to the display? Or do you mean various boat system wires?

Will update

Various boat system wires. None of these wires should touch the terminal post of the battery without first passing through the shunt. This is the only way the loads can be read.

Notice how there is NOTHING connected to the battery on the battery side of the shunt, except the shunt, in the illustration below. All loads must be wired on the load side of the shunt or they will never be captured or read by the battery monitor ...

 

[Rick]

Thanks again Maine. Im thinking I understand what you are talking about. I will find the last buss in the group and go from there.

One other thing I was considering is the power source to the display. If I wire it per the spec, the quage is always powered. I assume since it is smart it will filter out its amp draw. Will see what it takes to power the display. I might have to add an on/off switch for it.

As soon as it is light enough to work here is SAN, im gonna get after it!

 

[dwain6805]

Hey Rick,
I'm not busy today, give me a call if you need some "walking though" it.
Dwain
S/V Dancy
KP44 #279

 

[inarathree]

Maine Sail, so please clarify this for me, as the p/o of my boat really had the electircal fubar'd, and nothing was working. I replaced most of it last weekend, and just want to make sure it is done proper. My girl is an 84 H22 with a very simple wiring harness. I replaced the electrical panel, added a six post bus for the ground and a battery charger, which were not part of the original install.

Here are my questions:

1) According to what you said above, the charger I added, the ground should connect to the bus bar, and not the ground on the battery?

2) I have no earth ground, that I can find. What should i be looking for? And if/when I do find it, that also should be connected to the bus bar?

 

[Bill Roosa]

Boat grounding begin with the end in mind

Boat grounding is a complicated subject. WM advisor has a great article under the electronics section. Basically you need to consider the 12 volt DC ground, the 120 volt AC ground, the boat ground to sea water (earth), lightning grounding, and grounding your HF radio if you have one. These have contradictory requirements and if you do it incorrectly you can actually get the boat corroding away at a fairly high rate or subject yourself to a massive electrical mess if lightning ever hits.
For the DC electrical with a shunt all you need is all the ground (0 volt DC returns) to go through the shunt BEFORE they go to the battery. If you don't have a shunt then you can relax that and just remember to not overload any one ground terminal on the battery. Given the number of circuits the common solution is to have a ground buss bar to collect most/all the returns and then run one line to the batteries negative terminals. All the batts should have their grounds tied together BTW.

 

[inarathree]

So I should be ok that I just have the bus bar ground, and charger ground, going to the battery ground. I dont think that on a 22' boat i can over load it too much... can I?

I have an anchor light, running lights, interior lights, bilge pump, radio, and vhf. All seperate fuses (cause I had a six port panel). The ground from the panel goes to the bus bar, as do the grounds from all devices, and then the bus bar connects to the ground of the battery.

Oh and I forgot the ground for the o/b alternator, I also connected to the ground of the battery. Should that be moved to the bus bar?

 

[Maine Sail]

So I should be ok that I just have the bus bar ground, and charger ground, going to the battery ground. I dont think that on a 22' boat i can over load it too much... can I?

I have an anchor light, running lights, interior lights, bilge pump, radio, and vhf. All seperate fuses (cause I had a six port panel). The ground from the panel goes to the bus bar, as do the grounds from all devices, and then the bus bar connects to the ground of the battery.

Oh and I forgot the ground for the o/b alternator, I also connected to the ground of the battery. Should that be moved to the bus bar?

The big concern is too many terminals on one post. The ABYC suggests that four terminals per stud is the max allowed but this is a general maximum less may be the max in some instances. Four may be fine with small ring terminals but with big battery lugs, in parallel or series parallel, it leaves you with little more than room for two lugs, a lock washer and a nut before you run out of stud.

This is why it is a good idea to use a buss bar to free up the terminal stud on the battery for high current battery cables and sufficient connection of them. Wing nuts are also non-preferred for use on battery terminals.

 

[inarathree]

Thanks for the advice. I feel more confident in what I did.

 

[Stu Jackson]

I suggest that each of you do what MS and I and many others have done:

Draw a wiring diagram.

Writing paragraphs is NOT going to help.

You NEED to draw a wiring diagram and you might actually even be able to start seeing what's going on yourselves.

Then compare that to the instructions that came with your monitors.

Here's my diagram: Reply #23

http://c34.org/bbs/index.php/topic,4949.0.html

http://c34.org/bbs/index.php/topic,4949.0.html

 

[JVB]

If you are curious about the use and placement of an electrical shunt go to
http://encyclopedia.thefreedictionary.com/Shunt+(electrical)
and scroll down to "Use in current measuring"

 

[inarathree]

Thank you for your patience, answering my elementary questions. As I said, my boat is small - a 22'. I just like to make sure I do things right.

 

[Bill Roosa]

Couple of questions inarathree

Where is the starter motor and engine controls/gages?
Where is the tie to engine ground?
Does the boat have a 120 volt AC system?
Is the mast base connected electrically to the keel or other underwater metal part?

 

[Maine Sail]

Where is the starter motor and engine controls/gages?
Where is the tie to engine ground?
Does the boat have a 120 volt AC system?
Is the mast base connected electrically to the keel or other underwater metal part?

On most small OB powered boats the battery neg post is most often the ground point for the DC system. If you want lightning protection, which many of these boats do not have, especially center board boats, you would need to add that ground point which is usually the keel or an added ground point.

From ABYC E-11:

"11.5.4.7.2 The negative terminal of the battery, and the negative side of the DC system, shall be connected to the engine negative terminal or its bus. On boats with outboard motors, the load return lines shall be connected to the battery negative terminal or its bus, unless specific provision is made by the outboard motor manufacturer for connection to the engine negative terminal."

 

[FastOlson]

I agree with diagramming.
One method I find very useful is to draw up my diagram of wire runs, battery and post depictions, etc with a rough but recognizable layout based my own boat.

i.e. put all the device icons/symbols on approx. where they live in your boat, and then add the wiring lines, labeled carefully. Use color for the wire representations and size the lines you draw roughly in proportion to the their real size, i.e. a fat line for a 4/0 and a tin line for a size 12, and so on.

After a couple of tries and some re-drafting, it will start to make sense to you... and that's important.

While a true schematic is best for the experienced electricians, sometimes a more real-world visual version works better for us amateurs.

...just another .02 worth,

LB

 

[Maine Sail]

I suggest that each of you do what MS and I and many others have done:

Draw a wiring diagram.

Interestingly enough I do not use wiring diagrams when I wire boats. It all comes out of my head in the layout I have designed in my head. These are relatively simple systems once you have a basic understanding but that takes time. I will draw crude diagrams for others but not for myself when I wire.

If I showed you the scribble that was the "wiring diagram" for my own boat and the finished product you likely never believe it was done without a real "wiring diagram". I do work out component or buss bar layouts with carboard templates for such items as back planes / panel boards but that is about it.

Wiring diagrams are good though, I just don't use them personally on boats sub 40 feet with typical AC/DC systems as these are simple circuits. If I am trouble shooting or working on a boat that has existing factory wiring and does not have a wiring diagram or well labeled wires this can be a PITA cause most builders did not follow the ABYC color codes to begin with.

Even with a wiring diagram from the factory they are almost always suspect 10-20 years down the road and rarely represent how the boat is wired. If this is the case then it can benefit you to take the time to document, diagram and label the system wires. I will draw a diagram for my boat before I sell it, but I am in no hurry unless someone can send me a copy of an electrical diagram software that does not take years to be come proficient in. A simple software like MS Paint but with diodes, fuses, switches and all the other symbols I would like to have for laying out marine AC/DC systems.

In the meantime most of my wiring diagrams are drawn in ms paint so others can understand what I am trying to describe in words, easier...

Like this and as I said CRUDE:

 

[Rick]

Hey think I will step back in. If you scroll way up you will see where Maine Sail offered me some help. It worked! Thanks Maine and some interesting reading in this thread. I also studied your thread that was similar over on sailnet.

I found the buss behind the electrical panel. I hooked the ground wire to the shunt and the shunt to the buss before the various system grounds. I decided to get power to the display and tie in the positive where the main wire goes to the dc main breaker.

It worked well and it allows me because of my perko setup to read both engine and house battery states depending on which bank I select.

A quick and dirty pic of it. Top right hand corner

And Dwain, good to hear from ya. We are on the boat until tomorrow night. You in town?

 

[dwain6805]

Hey Rick,
no unfortunately I'm at home doing paperwork and such. I was just getting a chuckle out of the thread drift here and the required C34 been there done that everyone must check it out reply.
We'll be over there for one of the Xmas boat parades, I think around 12/19 or so. Taking the inlaws for a sail and some touring.
MS's last drawing is how simple this project should be. You don't need to rewire your boat to "ABYC" Stds to install a Bat Mon. Just make sure there are no connections between the shunt (battery side) and the neg terminal of the Bat or else your amp hrs will never balance out.