Shunt question

[maury]

Literature for the panel says “ Panels with meters include toggle switch for mounting up to 3 battery banks”. Given the back of the meter does not appear to be set up for three battery systems I assume the meter is for only one system.

[maury]

Good catch on the alternator error. I will just use it for house batteries to keep it easy and safe.

[Statistical]

Originally Posted by maury

Literature for the panel says “ Panels with meters include toggle switch for mounting up to 3 battery banks”. Given the back of the meter does not appear to be set up for three battery systems I assume the meter is for only one system.

Yeah the usually have a switch on the panel and that switches the voltage wire to one of three batteries. In most cases it is just a single shunt for current off the negative busbar.

Really big boats with complicated systems might need more but most people get by with just one shunt between house bank and negative busbar.

[jordanbigel]

I used to have one of these dual shunts with a Link 20 AND I used it to monitor 2 separate banks (which share a common ground, to the motor).

The reason this works is that the Link20 battery monitor accepts the (small) wires from the shunts into different terminals on the back. It's designed to take in these signal wires from the dual shunt. There is a button on the face which lets you switch between banks. There are newer more modern devices (like the Victron BMV-712 I think) which do the same thing.

I still have the Link20 and it works, but now I have 2 separate (individual) shunts which feed into the Link20 (not going into the why of that, not important). So it is feasible that if the Link20 can work with 2 separate shunts instead of the dual, which it can, then you MAY be able to feed the signal wires from the dual-shunt into 2 separate battery monitors, or some other dual-bank monitor.

If you do not have the docs for the shunt and the Link20, you will need them to figure out which wire goes where (not talking about the battery leads, everyone else has explained that part) - I'm talking about the twisted pair wires which connect to the little screws on the side.

I think this may be helpful. There is a lot more in the manual, I can email it to you if you can't find it online.

[maury]

So I have the ground going through shunt but need to get some small fuses before I could hook up + juice to the meter.

Appreciate all the assistance.

[maury]

Jordon, so my old shunt basically was part of a house system probably with and A-B battery selector. My situation with motor battery is different so I am going to leave the two separate. I actually have the parts of an old link system and the books all of which needs a new home. I also have the inverter converter which I have wanted to sell but never got around to it. Thought it would be easier to sell locally once I am on the water with my boat in a few weeks. The shunt definitely saved me some $ which is why I kept all the parts.

When I bought the boat old link system and whole electrical system was a messy pile of wires and the seller showed me what link wires to remove to start fresh.

[sinnerman]

Blue Sea sells shunts. Different shunts for digital vs analog gauges.

https://www.bluesea.com/search/results/shunts

cheers

[maury]

Ug! Thanks for the important insight Sinnerman.

[Statistical]

Originally Posted by maury

Ug! Thanks for the important insight Sinnerman.

BlueSea is telling a white lie to help customers match up the right shunt.

There is no such thing as a digital shunt exception aside for "smart" shunts which connect to some kind of network for sharing data.

A shunt simply produces a consistent voltage drop relative to the current. However they have to be matched to what the meter expect. A 500A 50mV shunt will show 50mV at 500A so it will show 25mV at 250A. However a 250A 50mV shunt will show 50mV at 250A.

For analog meters they normally can't be adjusted so the shunt must match what the meter expects. For any digital meter that isn't garbage there is usually a setting to tell the meter the shunt ratio so that when it sees 50mV it knows (examples above) if that means 250A or 500A of current.

A Blue Sea digital meter will work fine with a non-Blue sea shunt even one of a different ratio as long as you adjust the ratio in the meter so it displays the correct amperage.

[wholybee]

Originally Posted by sinnerman

Blue Sea sells shunts. Different shunts for digital vs analog gauges.

https://www.bluesea.com/search/results/shunts

cheers

Lol. That is a good one. A shunt is a shunt. There is no difference at all between analog and digital. As long as you match the mV/Full Scale for the shunt to the meter.

Bluesea must only be making that distinction because their particular digital meter happens to be 50mV/500A.

[maury]

Fabulous, thx wholybee. I just received my fuses so can complete shunt hookup this weekend.

[kubota]

with a dpdt switch, 2$ on amazon, u can monitor two banks with one monitor for amps fuction.
amp-hrs not so much.

[sailingharry]

One very important side note to keep in mind for shunts, amp meters, amp hour meters, etc. You MUST NOT connect any negative wires to the battery or the battery side of the shunt. There should be one large wire connected to the battery, and then to the shunt, with no stragglers connected at either end. This is an incredibly common mistake. Anything connected here won't be measured, defeating the entire purpose.

[CharlieJ]

@sailingharry #28:
+1; see this all the time.