Author Topic: WBjr with Victron battery balancers and bmv 702  (Read 159 times)

bennyspoon

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WBjr with Victron battery balancers and bmv 702
« on: August 03, 2018, 08:34:06 AM »
Hi gang, just looking for some info on the best way to do this.

About to install some ex ups agm batteries and thought i'd try these balancers out.

In the midnite documentation it appears I can connect the Victron pcb rhubarb to the other side of the midnite shunt. The shunts are both 500a.

If both shunts are connected in parrallel the WBjr would not see the loads { battery balancers and gauge unit} connected to the victron shunt,is that correct?

What are your thoughts?
Cheers,
Ben.

ClassicCrazy

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Re: WBjr with Victron battery balancers and bmv 702
« Reply #1 on: August 03, 2018, 12:39:00 PM »
What size batteries and what age are they ?
AGM batteries have a limited lifespan from the experience I have with them. A lot would depend on what demands you plan to put on them.  I would recommend you charge up each of your used batteries separately and do a load test on them to determine if they will keep the voltage up and also the available capacity of them.

As far as your question about the shunts - I can't visualize what you are talking about . Whatever is connected to the shunt sees the voltage drop across that shunt. In the Whizbang installation it should only have the negative battery connection on one side and nothing else if it is to work properly . So one side of whizbang shunt battery , the other side is all other  DC negative connections.

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

dgd

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Re: WBjr with Victron battery balancers and bmv 702
« Reply #2 on: August 03, 2018, 06:31:32 PM »
Bs, you are correct, the shunt connected to the wbjr will not ‘see’ the other shunt although if as CC says you have the wbjr shunt as the only connection tothe battery -ve then the current drawn by loads will be seen - just not separately from the charging sources input current.
Eg. 10amps charging input with 6 amps used by loads means the wbjr ‘sees’ +4 amps
If you want to have the actual current used by loads reported then you need use another shunt connected to some other device that displays/reports current
If you have second Classic in your system then a second shunt/wbjr can be used to monitor current at any other part of your setup, eg loads or indiviual load.
This is exactly what I do, using a shunt to inverter so I can see what DC current all of my AC loads need. The appropriate modbus registers in the Classic can then be downloaded to provide ongoing metering of loads current.
Classic 250, 150,  20 140w, 6 250w PVs, 2Kw turbine, MN ac Clipper, Epanel/MNdc, Trace SW3024E (1997), Century 1050Ah 24V FLA (1999). Arduino power monitoring and web server.  Off grid since 4/2000
West Auckland, New Zealand

bennyspoon

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Re: WBjr with Victron battery balancers and bmv 702
« Reply #3 on: August 03, 2018, 07:33:26 PM »
Hi Larry, Dgd,

my wording probably could have been a little better.

What I meant was that the victron pcb is attached to the same shunt as the wbjr, just on the opposite side of the shunt to the wbjr.

So that there would  be the battery negative ,then the shunt{ with both pcb's} then everything else on from there.

I am mainly wondering if the victron pcb is going to effect the readings of the wbjr and vice versa in any way.

Ben.

ClassicCrazy

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Re: WBjr with Victron battery balancers and bmv 702
« Reply #4 on: August 03, 2018, 09:52:40 PM »
It will read the voltage drop of that shunt whatever it is.  That is all it is doing .  It should not interfere with the voltage drop and then it does not effect what either device reads off from it.  Only the current going through the shunt is going to determine what is read by either device.

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

boB

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Re: WBjr with Victron battery balancers and bmv 702
« Reply #5 on: August 04, 2018, 01:49:41 AM »

The little screws on the 500 amp shunt present about 100 millionths of an Ohm to the PCBs that are reading that small amount
of voltage (50 millivolts if 500 amps are running through the shunt)...

So, the shunt is sitting at battery negative, plus or minus a maximum of 50 millivolts.  Neither the WB Jr. or the Victron PCB
is going to affect that small voltage worth a darn so as long as the PCBs are reading the voltage across the little shunt screws,
they should both work fine.

We see people using the WB Jr. and the Magnum BMK shunt monitor all the time too.  You could probably have all three of
these battery monitors (and more!) on the same shunt and they'd all probably work just fine.

One thing you don't want to do though, probably, is to have any of those PCBs connecting to the little shunt screws using
small wire a foot or so away from the shunt....  If you have to mount the PCBs that way, then that piece of wire can be
resistive and possibly affect the readings.

Just mount the PCBs as close to those screws as possible and hopefully using a short standoff so they are really close to
the screws best as you can.

boB
K7IQ

SolarMusher

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Re: WBjr with Victron battery balancers and bmv 702
« Reply #6 on: August 04, 2018, 07:48:43 AM »
We see people using the WB Jr. and the Magnum BMK shunt monitor all the time too.  You could probably have all three of
these battery monitors (and more!) on the same shunt and they'd all probably work just fine.
boB
On a 7 years old PAE Magnum system, I have WBjr +Bmk + Trimetric all mounted on the same shunt and they work fine.
A+,
Erik
Off Grid with 3.2kw PV | Classic 200/WBjr + Classic lite 200 | 2x Outback VFX3648 Epanel | 3x SPD300 + 1x Schneider HEPD80 | Hub + Mate + PSX-240 | 750Ah Rolls S-480 battery bank + Trimetric | 1200 watts DC water heater | 8000 Generac and 7200 watts Champion gas generators

boB

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Re: WBjr with Victron battery balancers and bmv 702
« Reply #7 on: August 04, 2018, 11:38:05 AM »
On a 7 years old PAE Magnum system, I have WBjr +Bmk + Trimetric all mounted on the same shunt and they work fine.
A+,
Erik

Good to know !  That combination can go into the case histories as well.

boB
K7IQ

SolarMusher

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Re: WBjr with Victron battery balancers and bmv 702
« Reply #8 on: August 05, 2018, 03:13:48 PM »
On a 7 years old PAE Magnum system, I have WBjr +Bmk + Trimetric all mounted on the same shunt and they work fine.
A+,
Erik

Good to know !  That combination can go into the case histories as well.

boB
System was installed in the basement so the trimetric was for upstairs monitoring. It's still working great.
A+
Erik
Off Grid with 3.2kw PV | Classic 200/WBjr + Classic lite 200 | 2x Outback VFX3648 Epanel | 3x SPD300 + 1x Schneider HEPD80 | Hub + Mate + PSX-240 | 750Ah Rolls S-480 battery bank + Trimetric | 1200 watts DC water heater | 8000 Generac and 7200 watts Champion gas generators