Two Shunts: Balmar SG200 + Victron BMV-712?

[rgleason]

Is it impossible to wire two shunts properly?

• Balmar SG200 Volt/Amp/Soc/Soh/Time remaining
• Victron BMV-712 Volt/Amp/Soc "Coulomb Counter"

Installation of both the Balmar and the Victron require close proximity to the Bank negative and for the shunt to be ahead of everything else.

Parallel installation will create a bypass and mess up the meters and counters.

Serial installation will also create problems.

Is it only possible to have a single meter on a battery bank?

[witzgall]

I cannot speak for Victron, but we (Balmar) have no issues if you wire the two shunts in series, one after the other, in the negative "Return" line to the battery bank. It really does not have any issues that we have found, maybe a very slight drop in voltage reported, that is all. I have this installed exactly this way on my boat.

What you cannot do, is take the sense wires from the Victron shunt and connect them to the Balmar SmartShunt.

Parallel, as you wrote, would make a mess of things and would not work at all, making both systems wildly inaccurate.

Chris

[rgleason]

Thank you. Chris!

I think I understand now, there is just a very small 50mv drop I guess which does not affect accuracy very much. I might need the BMV-712 to provide a high or low voltage disconnect.

[Jim Cate]

there is just a very small 50mv drop

And that only at max current for the shunt.

Jim

[Stu Jackson]

Originally Posted by rgleason

Thank you. Chris!

I think I understand now, there is just a very small 50mv drop I guess which does not affect accuracy very much. I might need the BMV-712 to provide a high or low voltage disconnect.

The mv actually IS the measurement "device" because all the meter you visually read does is multiply that voltage by "computing it" into amps. Magic!


rg, you did a nice job on collating so much good information and links in your Small Boat Electrical topic. It ought to be a sticky. Thanks.

[Paul L]

[QUOTE=witzgall;2778638]....

What you cannot do, is take the sense wires from the Victron shunt and connect them to the Balmar SmartShunt.

....../QUOTE]

Why can't you share a single shunt with two monitors, assuming they are both use the same shunt spec?

[Maine Sail]

[QUOTE=Paul L;2779509]

Originally Posted by witzgall

....

What you cannot do, is take the sense wires from the Victron shunt and connect them to the Balmar SmartShunt.

......

Originally Posted by Paul L

Why can't you share a single shunt with two monitors, assuming they are both use the same shunt spec?

Because the Balmar SG200 SmartShunt is not a typical shunt. It is proprietary shunt designed to be used only with the SG200 display.

[Paul L]

[QUOTE=Maine Sail;2779547]

Originally Posted by Paul L

Because the Balmar SG200 SmartShunt is not a typical shunt. It is proprietary shunt designed to be used only with the SG200 display.

Makes sense, but for 'normal' meters sharing should be fine.

[Jim Cate]

[QUOTE=Paul L;2779579]

Originally Posted by Maine Sail

Makes sense, but for 'normal' meters sharing should be fine.

Yep, you are putting two (or more) high impedance millivoltmeters across a very low impedence shunt. They will both measure the voltage drop across the shunt and not bother each other.

Does require that both panel meters are calibrated to the same full scale value, typically 100 mV for full scale reading (100 A or whatever). I've got one of the cheap chinese panel meters and its shunt is 75 mV for 100 A.

Jim

[mitiempo]

[QUOTE=Maine Sail;2779547]

Originally Posted by Paul L

Because the Balmar SG200 SmartShunt is not a typical shunt. It is proprietary shunt designed to be used only with the SG200 display.

The Victron shunt is also proprietary and will only work with a Victron monitor.

[Maine Sail]

[QUOTE=mitiempo;2779813]

Originally Posted by Maine Sail

The Victron shunt is also proprietary and will only work with a Victron monitor.

Victron is just using a PCB mounted to the sense terminals of a standard 500A 50mV shunt. It you measure where the PCB mounting screws are you'll get the same votlage drop reading as you would without the PCB...

[rgleason]

Rod I am not sure what this means.

Are we suggesting that someone skilled and careful could remove the Victron PCB and attach it in the same locations (with testing/calibration for the mV drop) on the Balmar Shunt in order to avoid having to use two shunts?

[CatNewBee]

the PCB of Victron can be mounted on any resistive shunt with appropriate dimensions. In fact Victron provides various shunts for different loads without the PCB to use the BMV monitors on different Ampere ranges.

There are other battery monitors out there that use magnetic HAL sensors or electronic sensors with built-in ADC for measuring the current, they cannot be connected to the Victron PCB, this is for resistor shunts only. You can adjust the shunt parameters in the BMV settings menu.

[Maine Sail]

Originally Posted by rgleason

Rod I am not sure what this means.

Are we suggesting that someone skilled and careful could remove the Victron PCB and attach it in the same locations (with testing/calibration for the mV drop) on the Balmar Shunt in order to avoid having to use two shunts?

No the Balmar shut is 100% proprietary. The Victron PCB can be mounted to other "standard" type shuts that have the same sense screw center to center dimensions. For example the Victron BMV PCB I have in the shunt bin will bolt directly to most older 500A 50mV LINK shunts but (not the new ones).


EDIT: Never mind I see Cat beat me to it..

[rgleason]

Thanks CNB and MS for the explanation.