Have I found the little Shunt??

Richard10002

Richard10002

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I've had a concerted effort to find the shunt which supplies the info to the Sterling battery monitor and wonder if I've found it? It's a bit tucked away, so cant get a great picture, but here's what I think it is:

IMG_0028.jpg


IMG_0023.jpg


havent found any big fuses on the battery wires yet /forums/images/graemlins/confused.gif

As the monitor only measures the amps used by the domestic bank, presumably the big red wires connected to it, are from the domestic bank?

Cheers

Richard
 
Closer inspection reveals a thick metal bar with a plastic cover with lots of slots.

Looks like another piece of the electrical wiring jigsaw is in place.

Thanks

Richard
 
I'd say you have found it. Yes the big red cable would go to the domestic supply if the shunt is in the +ve line (it is often/usually in the negative). Where does the yellow multicore cable go to? To the sterling monitor? If so that would be proof positive.
Ray
 
Bless you, Richard, you're trying hard but, you know, I find it slightly disturbing that you're off travelling the world and you seem not to have the first clue about half the kit on your boat. /forums/images/graemlins/confused.gif
 
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Bless you, Richard, you're trying hard but,...

[/ QUOTE ]

/forums/images/graemlins/laugh.gif

I wouldnt be surprised if that opens a can of worms /forums/images/graemlins/smile.gif

I dont know if I should be offended, or touched, or concerned, or...... ? and I know you dont mean to offend.... In fact, I'm more touched than anything else /forums/images/graemlins/smile.gif

Not sure whether it warrants a defence.... but....

I suspect I am not dissimilar to most people and their boats,

"What's a stern gland?" type of thing, but once you know, you know.

It's also a bit horses for courses.... some people astound me with there questions or responses to coll regs. and navigation issues.

I was always the kid in the class, (or on a course), who had no problems with asking a question if I didnt understand something, and push until I did - the question that most others were too shy to ask, so perhaps I'm more vocal than many.

This forum is full of people asking about stuff on their boats, it's what it's about.... and I guess I ask some of the questions both for my benefit, and for the benefit of others who follow.

Anyway... so far I've not had a problem which I havent been able to deal with with some common sense, and a lot of help here and on moa, so must be doing something right.

And you never stop learning.......

This is kind of a precursor for fitting a battery management system, so I need to know what wires go where, as some will have to be disconnected and isolated, some rerouted, some replaced, and some left alone.

Anyway - I thought it was the shunt and, without the benefit of this medium and this forum, i would have moved forward on that basis.... but thought it worth checking. No point reinventing the wheel eh?
 
I see where you're coming from. If you waited until you knew as much about your boat as the army of guys who designed and built it you'd never go anywhere.
I have a friend who is still working out how his freezer works, after 10 years. Hasn't stopped him sailing a couple of thousand miles a year.
 
I fitted a Stirling smart regulator with remote display this year and your photo looks just like mine. On my set up I have 2 shunts, and if I remember correctly the shunt for the starter battery is in the line from the regulator to the battery, while the other shunt which indicates the domestic battery state is in the line from the alternator to the regulator. I assumed that the computer worked out that the domestic current was equal to the total minus the starter current. If I am correct then your cables from the shunt may go to either the regulator or the alternator output. I would sugest that the safest course would be to physically follow the cable from the shunt to it's other end.
 
Richard

The purpose of a shunt is to syphon of a proportion of the big current flowing and use this for measurment purposes without having to take the heavy current flowing in the cable to the instruments etc. This means the metal part of the shunt bar will have a big connection at each end then somewhere on the shunt bar there will be two small gauge connections.

Possibly your shunt is more complex and there are more than two instrument wires going to different places but that is the basics of it.

The same thing is done in AC using current transformers but I doubt your installation has these though who knows what Mr Sterling might have got up to.

The thing you show certasinly looks like a shunt but with more instrument wires than I would expect.

Seems it is built to economy size and fitted with lots of heat sinkage!!!!
 
[ QUOTE ]
The purpose of a shunt is to syphon of a proportion of the big current flowing and use this for measurment purposes without having to take the heavy current flowing in the cable to the instruments etc. This means the metal part of the shunt bar will have a big connection at each end then somewhere on the shunt bar there will be two small gauge connections.


Seems it is built to economy size and fitted with lots of heat sinkage!!!!

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A shunt can also be a small plastic moulding that fits around a battery terminal or cable. This measures the magnetic field, converting it to current flowing and direction. It also has infinite overload capacity, and as it does not carry current, it does not get hot.

So you may not always be looking for a big chunk of metal, with two big terminals.

Brian
 
The cover is definitely that of a Sterling shunt. However, if memory serves, Sterling give you the choice of fitting to either the +ve or -ve. You can probably download the 'manual' (a typically eccentric Sterling job full of wild colours, capitals and exclamation marks) from their web site, the address of which I'd happily give you if it hadn't died with my last laptop.
 
[ QUOTE ]
the shunt will be on the negative

[/ QUOTE ] In most multi battery installations the shunt will be in the negative line, because that then measures the total battery drain amps and the total battery recharge amps - suitable for an A/H gauge to track total charge states.

Alternatively, the shunt may be in the positive line, either upstream or downstream of the 'charge' line. In the one case it will only be able to measure amps out, and in the other it'l measure amps in and out, and will be suitable for checking A/H totals for just one battery - usually the domestic.

If I remember, Richard has three banks; Engine, Domestic and Bow thruster/Anchor winch.

So, Qs for Richard:
1. Is the shunt definitely in the positive line? (certainly looks like it with all that red wire around)
2. Do you have an A/h meter reading as well as an amps reading?
3. Do you have any more shunts lying around? - like, one in the negative line?

Great fun tracing all these fat battery lines, but essential in the long term for design of charging systems installation . . .
 
If you understand what is SUPPOSED to be there, and how it should work, you will find "it". (by following wires, pipes etc.) You can test a shunt by measuring the (milli)voltage drop across it when current is flowing through it. If it doesn't have wires going from the measuring/sensing device (in question) to it, it isn't the shunt you're looking for - it might, however, be another one for an(other) ammeter for instance. I measure total current flowing to/from the batteries by sensing the voltage drop across the common negative cable between the engine and the batteries, without having a physical calibrated shunt in the circuit.(the microvoltmeter/ammeter is calibrated to suit using trimpots.)
 
On the same topic, is it possible to use the main fuse as a shunt? I realise that it will heat up and change its resistance to the detriment of the accuracy of the reading but these measurements are only rough anyway. I also realise that, if the fuse blows (which it is designed to do in fault conditions), there will be full volts across the sense wires. If the diverted current drives a digital sensor, this would not matter. If it were a moving coil sensor it would probably become an ex-moving coil sensor.
 
[ QUOTE ]
Alternatively, the shunt may be in the positive line, either upstream or downstream of the 'charge' line. In the one case it will only be able to measure amps out, and in the other it'l measure amps in and out, and will be suitable for checking A/H totals for just one battery - usually the domestic.

If I remember, Richard has three banks; Engine, Domestic and Bow thruster/Anchor winch.

So, Qs for Richard:
1. Is the shunt definitely in the positive line? (certainly looks like it with all that red wire around)
2. Do you have an A/h meter reading as well as an amps reading?
3. Do you have any more shunts lying around? - like, one in the negative line?

[/ QUOTE ]

It's almost certainly a Sterling shunt, (the installation instructions suggest the positive line, and that it may get hot).

I'm sure it's on the +ve line, having followed the domestic feed from the alternator to the shunt.

Ah and amps on the domestic bank. Volts only on Starter and bowthruster.

Havent seen any more shunts, and I'm sure I've been everywhere on the boat by now.... I've known this thing existed for ages, and always thought it was the shunt... but have only now got round to giving it some attention.

Thanks again

Richard
 
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