Installing Amp meter and shunt

[Phil23]

I need to monitor Amp draw down and any leakage utalizing an amp meter and shunt how ever I am unsure where to mount the unit.
I have a 3 battery system through 2 isolation switches.


The positive lead from the batteries arrive at a positive terminal in the switch panel as does ships earth.


I appreciate the shunt is installed in parallel with the amp meter however unsure which line to mount the shunt into.

 

[Lepke]

Positive

 

[Insequent]

If you buy a battery monitor, such as the Blue Seas ones, it will come with an installation guide and diagram.

It is normal for the shunt to be installed close to the battery (or battery bank) that is to be monitored, and it will be on the NEGATIVE lead. There should be nothing connected between the shunt and the battery, and nothing else on the battery terminal apart from the lead to the shunt. Shunts have a polarity - if you have negative readings then swap the connections on the the shunt.

If you want to measure current for 3 seperate batteries, then a negative busbar from the batteries and then to the shunt (no other connections to batteries or battery side of shunt!) would do that, and depending on how your isolation switches are configured you could then see the draw on each battery by isolating the other two.

 

[psneeld]

Most of the install diagrams I have seen call for the shunt to be installed in the Negative cable.

You may need 3 shunts and a 3 position switch to the meter unless you draw from all 3 batteries at the same time.

Check out some wiring diagrams on the net.

 

[Jgutten]

Look at the Smartgauge by Ballmar. I put one in our boat and it works great. Reads charging voltage for each bank and the status of the house battery by percentage. No shunt needed.

 

[FF]

I hope you mean a SOC (state of charge) meter not just an amp meter.

The SOC meter will be useful as a "gas gauge" to tell how charged your batts are , so you can manage them for longer installed life..

To be accurate it has to know ALL the batts and charging & discharging , and usually everything passes thru the same neg lead. Engine starter excepted.

 

[psneeld]

If interested in the Balmar Smartguage, it's tech I believe was aquired by a British company called Merlin Power Systems who markets the same device for about 1/2 or 2/3 price unless it has been jacked up recently.

Check around snd you may find thd same device ar a bargain price.

 

[caltexflanc]

Look at the Smartgauge by Ballmar. I put one in our boat and it works great. Reads charging voltage for each bank and the status of the house battery by percentage. No shunt needed.

Those are really great, but they don't include an amp meter. Nice to know how many amps are going in or out of the battery(s) at any given point in time.

Shunts goes on the negative by the way.

 

[DavidM]

Battery monitors, which measure amperage and amphours over time, should be installed in the battery's ground as noted (by most) above.


You don't say what the three battery banks are used for, but if two are starting (propulsion and generator?) then there really is no need to monitor those. They normally stay well charged and amphours used would not be helpful. If you have two house battery banks (why? not the best setup) then you could put the shunt in a common ground for the two banks and that will measure total amphours for the two. But again, why? It won't be very helpful in managing the batteries, ie knowing when to turn on a genset or ???



If you must have two house battery banks then there are battery monitors with two shunts and a selector to monitor each, or get another battery monitor.



David



David

 

[C lectric]

To get the best advice then provide a schematic. It does not have to be
pretty , hand drawn is fine. But it does need to show the battery connections and where the feed cables, + & - , go.

This includes any main power switches such as the ubiquitous 1/2/all/ off switches. Otherwise we are mostly flying blind. Descriptive advice can be good or bad but only as good as the info we get.

 

[Ski in NC]

I have three banks (house, thruster, engine/gennie starting) but my ammeter (and shunt) is only on the house bank. See no need to meter the starting and thruster batts. I do have an accurate switchable voltmeter that monitors all three banks, if volts are happy on the meter, all is well with thruster and start bank.

 

[Dougcole]

I'm following this thread with interest, as I'm getting ready to install a Victron BMV-700 on my house bank.



So if I read this correctly, there should be nothing connected to the negative terminal other than the shunt. I have 4 6V GC batteries in series and parallel as a house bank. Does the cable for the shunt replace the (-) cable that goes from my (-) terminal to the ground buss bar? So the shunt cable goes from the terminal to my buss bar?


Thanks in advance.

 

[DavidM]

I'm following this thread with interest, as I'm getting ready to install a Victron BMV-700 on my house bank.

So if I read this correctly, there should be nothing connected to the negative terminal other than the shunt. I have 4 6V GC batteries in series and parallel as a house bank. Does the cable for the shunt replace the (-) cable that goes from my (-) terminal to the ground buss bar? So the shunt cable goes from the terminal to my buss bar?

Thanks in advance.

Yes
David

 

[Phil23]

I also see there are amp meters with integral shunts as these a go

 

[Phil23]

Ok I should clarify I am only requiring the draw down/discharge from my house battery when at rest and not with the start/crank batteries in line ie with only the house battery turned on at the isolation switches.
Large black cable to NEG bar is ships earth and large orange cable to POS plate/bar is main feed.

 

[dhays]

Not sure anyone has posted this link, but here is the article that CMS wrote about it that you can find on his website. Anyone interested in installing a monitor, or interested in how they work should give it a read.

https://marinehowto.com/installing-a-battery-monitor/