BMK Shunt

[Triboy]

Looking for a little expertise.

I recently installed in my motorhome a Victron SmartSolar 100/50 to control my 1 X 260 W solar panel (will be installing another 260 W panel in very near future) that feeds into 4 AGM 6 volt batteries. I currently use a Magnum BMK and Magnum ME-RC remote to monitor the batteries which works OK but I’ve been thinking about installing a Victron BMV-712 battery monitor, so you solar experts out there can I replace the Magnum’s shunt with the Victron’s and then wire the Magnum BMK up to the Victron shunt?

Thanks for your expertise.

Graeme Arnott
07 Country Coach Allure 430

[ALLOY]

If both shunts are the same size I don't see a reason why the BMK couldn't be wired across the Victron Shunt.

[baphenatem]

The manuals for both products indicate they use the same 500A/50mV shunt, so it should work either way.

[Triboy]

Thanks for the input guys, it makes the decision a little easier now.

Graeme Arnott
07 Country Coach Allure 430

[BatteryPro]

Be sure the Victron sense wire set to the kelvin screws is twisted well, like the Magnum wire is. This will prevent errors.

Larry

[Triboy]

Thanks I'll keep that in mind when I do the install.

Graeme Arnott
07 Country Coach Allure 430

[gatorcq]

use 1 shunt for both units.
I have Magnum and Midnite. Used the same shunt but use the modules for each Controller. Measuring mV, is still measuring mV for each until. It was nice to see how closely they measured together.

[Triboy]

Thanks for the input gatorcq, good to hear that they produced similar results. I’m seeing some close battery voltage numbers as well with the Magnum and the Victron iPhone app, the results are within .05 volts. The other info from the solar panel to the controller and to the batteries is, for me, very interesting, this is my first attempt at solar and it’s quite intriguing (see iPhone screen shot)

The Victron app is apparently capable of displaying battery output (cutoff from the screen shot below) but I suspect that until I install the Victron shunt the output won’t be shown.

Although I did think about trying to wire the controller to the Magnum shunt rather than the negative side of the battery as per what the Victron controller manual states. Anyone have any thoughts on that?

And one more question, the Magnum remote is not showing any increase of DC amps when the panel is producing juice. Does anyone know if the Magnum is capable of showing this?

Other than the problems I’m having with the controller’s bluetooth range and connecting issues with my iPhone (next little problem) it’s an impressive little pairing, but I think I’d still like to have the display monitor hardwired and located in the same location as my other controls rather than dragging out a phone or tablet.

Thanks again for your suggestions.

Graeme Arnott
07 Country Coach Allure 430

[C.Martin]

Originally Posted by Triboy

And one more question, the Magnum remote is not showing any increase of DC amps when the panel is producing juice. Does anyone know if the Magnum is capable of showing this?

The Victron display will show the Volts and Amps leaving the charge controller.

The Magnum display will show the Volts and amps measured at the shunt and actually going in or out of the Battery Bank.

The difference can be...when the current is flowing toward the shunt from the charge controller, it can make a detour and head for Your Inverter or the RV’s DC loads...and not make the journey thru the shunt. So if thirty amps are leaving the charge controller...but only twenty are going into the batteries...you must be using 10 amps for other things...

[Triboy]

My Magnum remote wasn’t showing any input from the Victron controller so I tried changing the cable from the house battery (-) to the Magnum shunt and now I’m seeing input on the Magnum remote and so far so good with no effect to the controller..

I'd still like to put the Victron Bluetooth battery monitor in but price up here in Canada for the kit is outrageously expensive, so it will have to wait until we pass by AM Solar in Oregon in the spring.

Graeme Arnott
07 Country Coach Allure #31500

[C.Martin]

Originally Posted by Triboy

My Magnum remote wasn’t showing any input from the Victron controller so I tried changing the cable from the house battery (-) to the Magnum shunt and now I’m seeing input on the Magnum remote and so far so good with no effect to the controller..

I'd still like to put the Victron Bluetooth battery monitor in but price up here in Canada for the kit is outrageously expensive, so it will have to wait until we pass by AM Solar in Oregon in the spring.

Graeme Arnott
07 Country Coach Allure #31500

Graeme,

When you reconnected the ground...was your Magnum BMK in Learning mode for a long time? If so...you might compare amps reported by the BMK meters display to those obtained using a dc clampmeter on the battery ground lead...

The network devices can be damaged if you remove the negative lead from the Inverter before disconnecting the positive lead to the Inverter... If you pulled the Inverter positive lead first...then no worries.

There is a caution in the Magnum manuals which state that the Inverter can try to find an alternative ground thru the sensitive network devices and damage them.

[Triboy]

Fortunately I didn’t run into any issues. I switched off the house battery cutoff before making any disconnects, then disconnected the negative on the house, didn't touch the inverter wire from the load side of the shunt. Disconnected the Victron from the house negative and installed it on the battery side of the shunt. Turned things back on and all was well, Magnum started showing some DC from the solar panel, which I wasn’t seeing previously. We’re currently on a 4 day trip right now and no problems while running on house batteries to our destination and now plugged into 50amp service and all things still good.

Thanks for the heads up I’ll do a little more reading next time before I play with things.

Graeme Arnott
07 Allure 430 #31500

[C.Martin]

I’m about to do the same thing.

I wanted to add battery temperature for SmartSolar voltage compensation.

I’m trying to make sure that if I add the Victron Shunt...piggyback my ME-BMK sense module...that both will give accurate SOC readings... and then adding the temperature sense to the BMV-712... finally adding a VE.Direct cable between the BMV-712 round display and the MPPT150/100 Charge Controller for temperature and voltage data sharing.

I wanted to add the Smart Battery Sense...but my charge controller is one that is not compatible with the VE.Smart wireless networking scheme.

If you’ve completed your addition...please share your comments. i’d Love to know how it’s working out.

[Triboy]

Apologize for the late response just returned from a vacation in East Africa, will hopefully get the BMV-712 from AMSolar within the next week.

Graeme Arnott

07 Country Coach Allure 430