2 Shunts / 2 Battery Monitors ?????

tr0y
tr0y Solar Expert Posts: 99 ✭✭✭
in Off Grid Solar & Battery Systems #1
Equipment question, I have a Midnite Classic 150 & Whizbang Jr battery monitor, I also have new in the box a Victron BMV-712, for the heck of it I would like to use both to monitor batteries. 

Here is where I have questions, is they both need a shunt, the Whizbang JR attaches to the existing shunt and then the Victron monitor has a connector and board on its shunt. After looking at both shunts, it seems to use both monitor devices I would need to use both shunts due to different attachment methods for the printed circuit boards. Can I run these in-line, parallel ? And still get an accurate read ? Or is this a bad idea ? Thoughts anyone ? 

Thanks 


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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    edited June 2019 #2
    I am using MidNite Whizbang Jr with a Bogart Tri-metric on the same shunt, there are detailed instructions as to how this is done in the literature  that comes with the Whizbang Jr.  

    The Bogart Tri-Metric has small wires that attach to the small terminals, the Whizbang Jr is installed first, then the spacers, then the wires or board on the same terminals.

    I see no difference in stacking the two boards than the Whizbang Jr with the Tri-Metric wires  That said, I've never seen that Victron monitor, it should be no problem as they are both millivolt range voltmeters that read the voltage across the shunt

    Its a matter of using the longer screws and spacers that are provided with the Whizbang Jr. or a visit to the hardware stope for longer 6-32 screws and spacers

    Ace hardware has by far the best selection of small hardware such as this

    these monitors only read the voltage drop across the shunt and need no power from the shunt, it should be no problem to get the longer screws and spacers to stack the two boards, they will not interfere with each other. Keep  the two boards a bit separated 

    I have two Classic's, two battery banks and two shunts with dual battery monitors for about 5 years now, never an issue with that setup.
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #3
    As tecnodave says, they may both work off the same shunt.  Just check to be sure they both spec the same (50mv?) shunt.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #4
    Estragon, 

    good catch......some shunts are 100 mv.  
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,599 admin
    #5
    And many BMS monitors--You can program what shunt they have (xxxmV per yyy amps).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #6
    Whatever you choose, don't parrallel the shunts, that way each will read 50% of the current, assuming equal resistance for both.

    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • tr0y
    tr0y Solar Expert Posts: 99 ✭✭✭
    #7
    @mcgivor
    Thank you, that was really what I was wondering. 

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  • Simonb
    Simonb Registered Users Posts: 1 ✭
    #8
    I just received my Whizbang jr and wanted to keep my AiLi meter and shunt. The shunt that came with it is a 500a 75mv but the whizbang one is 50mv. I guess in this case I should just add them in series since they are different. Would there be a preferred order of the two shunts?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,599 admin
    #9
    No--Not really any series order specific (assuming the two voltage sense leads are "floating"--If you only had one voltage sense lead and ground, another issue).

    I looked around--And I could not find anything from Midnite that said you could program for a different shunt--And nothing from AiLi that you can program for a different shunt--So at this point, unless in your manuals/experience that you can program for the "same shunt" (such as 500 Amps @ 50 mV for both)--You are stuck with using two shunts.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • petertearai
    petertearai Solar Expert Posts: 471 ✭✭✭✭
    #10
    In series and  they  should work completley independent of each other.
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . Mate 3. victron battery monitor . 24 volts  in 2 volt Shoto lead carbon extreme batterys. off grid  holiday home 
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