question

gmmarich avatar image
gmmarich asked

BMV-712, on a single battery is displaying a Mid Voltage alert. The voltage reads 13.64 volts

BMV Battery Monitor
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1 Answer
Justin Cook - Bay Marine Supply USA avatar image
Justin Cook - Bay Marine Supply USA answered ·

@gmmarich, how do you have the shunt connected? The PCB on the shunt measures midpoint voltage through the "B2" port on the PCB; what do you currently have connected to the "B2" port, given that you only have one battery?

If you're using a temp sensor and have correctly wired it into both the B1 and B2 ports, replacing the single PCB power wire included in the BMV kit, then you'll need to configure the BMV appropriately, which setting is located in VictronConnect>Settings>Misc>Aux Input


bmv-aux.jpg (39.6 KiB)
7 comments
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kayjay avatar image kayjay commented ·
This answer doesn't appear to be correct. I'm having a similar problem and I have the positive lead in B1 as per Victron instructions. If I change it to B2 then there is no power to the monitor. According to the wiring diagram B2 is for starter battery measurement and B1 for power and leisure battery measurement and must always be present. The other option is the temp sensor device which I don't use.


My display gives a midpoint reading of 99.6% all the time. How can I set up to get a correct reading of less than 2%. I use flooded lead acid batteries.

Thanks

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kevgermany avatar image kevgermany ♦♦ kayjay commented ·
You should not configure midpoint voltage in the BMV settings unless you need a midpoint reading. Leave it as starter battery.
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kayjay avatar image kayjay kevgermany ♦♦ commented ·

The victron wiring instructions say to connect to B1 which is leisure. The starter connection is a secondary connection in addition to the leisure connection, the monitor won't work because there is no power to it using B2 only for the starter.


I have the app set to none rather than starter because I don't have it connected to the starter battery.


My issue is the reading of 99.6%, I need to know why. This is so I can change the app when I want to to enable a midpoint reading. If I'm getting 99.6% something is wrong and I want to know how to put this right rather than just ignoring it by using a different setting, which could lead to an undesirable situation without my knowledge. I'm always concerned about battery care. Thank you.

Edit .... I've now found out why I'm getting this problem, someone on a different forum explained it. Basically B1 and B2 need to be connected directly to the positive post as I have 2 x 12v leisure batteries.

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kevgermany avatar image kevgermany ♦♦ kayjay commented ·
What voltage is your system? B2 is usually disconnected.
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kayjay avatar image kayjay kevgermany ♦♦ commented ·
It's a 12v system on a narrowboat. The wiring diagram indeed says not to connect B2 when just measuring leisure batteries, it shows a connection to B2 when also measuring the starter battery along with the leisure batteries. I'm happy that I've got my answer from someone on another forum, where both B1 and B2 are connected, B1 to the positive busbar and B2 onto the batteries to make the measurement, all works correctly now.
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ kayjay commented ·

@Kayjay If you have nothing connected to B2 you have to set it to "none".

If you set it to "mid-point" and it measures 0V because there is nothing connected it is logical that it gives you an alarm due to a to high mid-pint difference.

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kayjay avatar image kayjay Matthias Lange - DE ♦ commented ·
You are quite correct and that setup was why I was getting the error. I was trying to find out what I needed to do to enable an accurate midpoint reading, I got the solution via another forum as you can see in my edit in the post you replied to. Thank you for your input, all info is valuable when working on a new system. Appreciated.
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