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Old 12-03-2011, 16:29   #1
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More than One Shunt

I have a shunt for my main battery monitor system (Link 10) and I also have a shunt for my Magnum Energy Inverter/Charger.
I'm thinking that I have to hook one up after the other as opposed to being able to hook both up to one shunt but I don't know for sure.
I also know that which ever shunt/monitoring system that is place second in line will not be considering the actual power use of the first shunt. I wouldn't think that would be much though.
Any comments or thoughts?

Thanks,
Extemp.
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Old 12-03-2011, 16:51   #2
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Re: More then one shunt

A shunt for inverter/charger? You're kidding me right?

Anyway, multiple shunts should be installed in series. Each device using it's own shunt, with exactly 2 conductors (not more/less) connected to each shunt.

cheers,
Nick.
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Old 12-03-2011, 17:12   #3
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Re: More then one shunt

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Originally Posted by s/v Jedi View Post
A shunt for inverter/charger? You're kidding me right?

Anyway, multiple shunts should be installed in series. Each device using it's own shunt, with exactly 2 conductors (not more/less) connected to each shunt.

cheers,
Nick.
Ahhh..... no.
It's a Magnum Energy MS2000 Inverter/Charger with a ME-BMK_Battery Monitor.
MS Series Inverter/Chargers
ME-BMK Battery Monitor Kit

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Old 12-03-2011, 17:35   #4
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Re: More then one shunt

Quote:
I also know that which ever shunt/monitoring system that is place second in line will not be considering the actual power use of the first shunt.
Because they are in series they each will read the current flowing in the DC system.
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Old 12-03-2011, 19:33   #5
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Re: More then one shunt

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Originally Posted by s/v Jedi View Post

Anyway, multiple shunts should be installed in series. Each device using it's own shunt, with exactly 2 conductors (not more/less) connected to each shunt.
Hi,

Why exactly 2?

I thought Trimetric used more (?).

b.
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Old 12-03-2011, 19:50   #6
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Re: More then one shunt

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Originally Posted by barnakiel View Post
Hi,

Why exactly 2?

I thought Trimetric used more (?).

b.
What makes you write that? May be the power leads for the meter/monitor itself (which should connect at the switch panel) but the DC current sensing with a shunt is always just a resistor where the voltage drop it causes is measured.... with 2 conductors.

Edit: I wrote 2 conductors because I have seen people use the shunt as busbar.

cheers,
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Old 12-03-2011, 20:06   #7
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Re: More than One Shunt

Quote:
Originally Posted by Extemporaneous View Post
I have a shunt for my main battery monitor system (Link 10) and I also have a shunt for my Magnum Energy Inverter/Charger.
I'm thinking that I have to hook one up after the other as opposed to being able to hook both up to one shunt but I don't know for sure.
I also know that which ever shunt/monitoring system that is place second in line will not be considering the actual power use of the first shunt. I wouldn't think that would be much though.
Any comments or thoughts?

Thanks,
Extemp.
I use a link 10, "monitor", and it has one shunt right at the house batteries in the neg line. There should be no more shunts, nor can you monitor another bank with the same link 10. For this reason I have all 3 charging sources go to the house bank, (15 X as expensive as the engine battery), and monitor that bank with the link 10. It has a Blue Sea battery combiner to allow the spillover (when being charged), to top off the small engine battery, which being always 98% full, I monitor with a simple v meter. This system has been remarkably accurate and done the trick for us for 15 years... Much of your question baffles me. I hope this helps a bit,

Mark
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Old 12-03-2011, 21:45   #8
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Re: More than One Shunt

Quote:
Originally Posted by Mark Johnson View Post
I use a link 10, "monitor", and it has one shunt right at the house batteries in the neg line. There should be no more shunts, nor can you monitor another bank with the same link 10. For this reason I have all 3 charging sources go to the house bank, (15 X as expensive as the engine battery), and monitor that bank with the link 10. It has a Blue Sea battery combiner to allow the spillover (when being charged), to top off the small engine battery, which being always 98% full, I monitor with a simple v meter. This system has been remarkably accurate and done the trick for us for 15 years... Much of your question baffles me. I hope this helps a bit,

Mark
Hi Mark,
I have a Link 10 also. I also (additional to) have another battery monitor system, a Magnum Energy ME-BMK Battery Monitor Kit .
I realize that I only need one battery "monitor" but have 2 and so want to employ both so long as I can do it in a way that won't compromise the Link 10 monitor which WILL be my primary Battery monitor. I think?? that can be done by putting the shunt for the Magnum Energy Battery Monitor farther away from the batteries then the Link 10 shunt (on the negative battery cable). The Link 10 would then pickup ALL the power usage including the power used by the shunt of the Magnum Energy shunt if that is any (doubt it).
If you're up for it, have a look at my attempt at a line diagram for my power system. I hope that un-baffles things? Not likely, I not doing well on the communications front tonight.

AC / DC Line Diagram ( Partial, Mostly )

Cheers,
Extemp.
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Old 13-03-2011, 07:34   #9
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Re: More than One Shunt

I would select one monitor and install only that one. Limit shunts as much as possible.

cheers,
Nick.
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Old 13-03-2011, 12:21   #10
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Re: More then one shunt

Quote:
Originally Posted by s/v Jedi View Post

What makes you write that? May be the power leads for the meter/monitor itself (which should connect at the switch panel) but the DC current sensing with a shunt is always just a resistor where the voltage drop it causes is measured.... with 2 conductors.

Edit: I wrote 2 conductors because I have seen people use the shunt as busbar.

cheers,
Nick.
Some of the advanced units will use an extra wire. As far as I remember from the manual the 3rd cable is to allow for the drop in the wire run (as opposed to the sum of the drop in the wire run AND the shunt). So the unit measures the drop in the wires+shunt, then in the wires only (2 of the 3 wires are attached to the same terminal), then from this calculates the drop on the shunt only.

Vide: attachment.

This is from Trimetric.

I might be mixing up things. If I do, apologies to the readers.

b.
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Old 13-03-2011, 13:43   #11
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Re: More than One Shunt

There are only a few different resistor values for shunts. So often they can be interchanged from one device to another.
If both devices using the shunt have a high measuring impedance, as I would expect, you could connect both devices to the one shunt, if the shunts have the same resistance.
Measure the resistance value of the 2 shunts if they are the same using 1 shunt should be fine.
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Old 13-03-2011, 15:44   #12
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Re: More than One Shunt

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Originally Posted by noelex 77 View Post
There are only a few different resistor values for shunts. So often they can be interchanged from one device to another.
If both devices using the shunt have a high measuring impedance, as I would expect, you could connect both devices to the one shunt, if the shunts have the same resistance.
Measure the resistance value of the 2 shunts if they are the same using 1 shunt should be fine.
noelex 77,
Thanks for thinking about my question and answering, as opposed to just saying... No, don't do that.
I'll check when I can... but am leaning toward putting the shunts in series unless of course someone tells me why I shouldn't?? I do understand that it would add 2 additional connections to the system.

Cheers,
Extemp.
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Old 13-03-2011, 15:58   #13
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Re: More than One Shunt

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Originally Posted by Extemporaneous View Post
? I do understand that it would add 2 additional connections to the system.
The other drawback of 2 shunts is you are also adding a bit move resistance and therefore voltage drop. Not much, but the little bits do add up.
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Old 13-03-2011, 16:12   #14
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Re: More than One Shunt

A shunt is a very low value dropping resistor whereby a repeatable voltage drop can be measured by a volt meter. Your measuring device is simply a voltmeter whereby the information from that measurement can be used in various forms, (Volts, derived amps). If both instruments can use the same voltage to to provide the required calibrated input for both of them then you can do the job with one shunt, however shunts are very low in resistance and offer no load to the circuit. If you wish to compare the two shunts you will require a very good quality low resistance measuring device ( galvanometer) I would use the two in series and avoid the possible error. Three wires are often used in instruments that measure voltage from a distance to compensate for the voltage drop in the measuring circuit wires.
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Old 13-03-2011, 16:20   #15
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Re: More than One Shunt

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If you wish to compare the two shunts you will require a very good quality low resistance measuring device ( galvanometer)
Just measure current and voltage drop over the shunt with a simple multimeter (or 2 would be easier) Ohms law will give you the resistance value.
Most shunts are 1mOhm, 0.5mOhm or 0.375mOhm.
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