BMV 712 install - Wiring for two battery sets?

[Yoda]

I decided to post this separate from my install as it is really and independent question. I have followed the quick install instructions https://www.victronenergy.com/upload...tion-guide.pdf
and the manual with the main wiring. https://www.victronenergy.com/upload...R-DE-ES-SE.pdf

I am now wiring the connection to the display head (RJ12) and primary battery feed 1. which I tied to the Lynx power in bar so it sees both battery sets.

Connection at the shunt shown

Connection to the Lynx power in bar - same post with CERBO GX power feed.

I then got to thinking and reading that the unit is capable for monitoring two battery's. Yes I should have stayed in my corner on this one. In reading the quick install instructions (steps 11 or 12) I get confused. Step 11 shows the second battery set up with moving wires around on the shunt Step 12 shows a midpoint connection which is not my case.

What I have is 4 6V GC2 batteries in a series parallel connection. Series to tie the 2 batteries together for the 12V and then parallel connecting the two sets separately to the Lynx power in bar. I am running separate positive and negative feed cables off of each set to the Lynx power in bar. This way I can isolate a set of batteries if needed.

This photo shows the separate battery positive cables (through switches) and the separate battery negative cables (connections under covers) tying into the Lynx power in bar (center of photo below MPPT and CERBO GX units).

This is the Question. Can I wire the two battery connections off the shunt to the 12 V positive terminals on each set of series battery's to get two separate battery readings? I was wondering if this would work - especially if I haft to disconnect one set of batteries?

Thanks for the help
Keith

[Guest]

I decided to post this separate from my install as it is really and independent question. I have followed the quick install instructions https://www.victronenergy.com/upload...tion-guide.pdf
and the manual with the main wiring. https://www.victronenergy.com/upload...R-DE-ES-SE.pdf

I am now wiring the connection to the display head (RJ12) and primary battery feed 1. which I tied to the Lynx power in bar so it sees both battery sets.

Connection at the shunt shown

Connection to the Lynx power in bar - same post with CERBO GX power feed.

I then got to thinking and reading that the unit is capable for monitoring two battery's. Yes I should have stayed in my corner on this one. In reading the quick install instructions (steps 11 or 12) I get confused. Step 11 shows the second battery set up with moving wires around on the shunt Step 12 shows a midpoint connection which is not my case.

What I have is 4 6V GC2 batteries in a series parallel connection. Series to tie the 2 batteries together for the 12V and then parallel connecting the two sets separately to the Lynx power in bar. I am running separate positive and negative feed cables off of each set to the Lynx power in bar. This way I can isolate a set of batteries if needed.

This photo shows the separate battery positive cables (through switches) and the separate battery negative cables (connections under covers) tying into the Lynx power in bar (center of photo below MPPT and CERBO GX units).

This is the Question. Can I wire the two battery connections off the shunt to the 12 V positive terminals on each set of series battery's to get two separate battery readings? I was wondering if this would work - especially if I haft to disconnect one set of batteries?

Thanks for the help
Keith

Keith,

You should be able to connect to measure the midpoint voltage at the series termination to get 12V from two batteries.

Jim

[Yoda]

Keith,

You should be able to connect to measure the midpoint voltage at the series termination to get 12V from two batteries.

Jim

Sorry Jim, I probably need more coffee to understand. I don't have a mid point that I know of - just two sets of 6V battery's tied together to make 12 volts, then each pair tie to the positive bus bar separately. Are you saying tie the two wires from the shunt to each set of battery positive terminals?

Thanks for you understanding - trying to understand and minimize the smoke at start up.

Keith

[Guest]

Sorry Jim, I probably need more coffee to understand. I don't have a mid point that I know of - just two sets of 6V battery's tied together to make 12 volts, then each pair tie to the positive bus bar separately. Are you saying tie the two wires from the shunt to each set of battery positive terminals?

Thanks for you understanding - trying to understand and minimize the smoke at start up.

Keith

Keith,

Your mid-point would be where two 6V batteries are connected in series.

Jim

[Yoda]

Keith,

Your mid-point would be where two 6V batteries are connected in series.

Jim

OK that makes sense. However do I need that? I am trying to monitor the two 12V sets to make sure the 6V pair is working together. Right now as wired the BMV will see the entire battery bank (both sets).

Thanks for helping
Keith

[Guest]

OK that makes sense. However do I need that? I am trying to monitor the two 12V sets to make sure the 6V pair is working together. Right now as wired the BMV will see the entire battery bank (both sets).

Thanks for helping
Keith

Keith,

I scan over these posts since I'm still working on getting ready to sell in MI and thought you were interested in the mid point voltage so perhaps I misunderstood your intentions. Keep in mind while you can monitor the mid-point, its really the two 6V batteries that are being monitored effectively as one 12V battery. I would not bother measuring the mid-point.

Jim

[Yoda]

Keith,

I scan over these posts since I'm still working on getting ready to sell in MI and thought you were interested in the mid point voltage so perhaps I misunderstood your intentions. Keep in mind while you can monitor the mid-point, its really the two 6V batteries that are being monitored effectively as one 12V battery. I would not bother measuring the mid-point.

Jim

Thanks Jim

[Cate&Rob]

Yoda
Hi Keith,

The Victron gauge can only monitor voltage for the second battery. All the other capabilities (amps, hours, %, etc) are for the primary battery (or battery bank) only. The original marine application for this monitor is primarily for the “house” bank but with the ability to keep an eye on the separate starting battery.

Rob

[Yoda]

Yoda
Hi Keith,

The Victron gauge can only monitor voltage for the second battery. All the other capabilities (amps, hours, %, etc) are for the primary battery (or battery bank) only. The original marine application for this monitor is primarily for the “house” bank but with the ability to keep an eye on the separate starting battery.

Rob

Thanks Rob
Ill go with the what I have it then and not worry about the second battery voltage only.

Was a long day today.

Thanks again for the clarification
Keith back to my corner

[ncitro]

Thanks Rob
Ill go with the what I have it then and not worry about the second battery voltage only.

Was a long day today.

Thanks again for the clarification
Keith back to my corner

Rob is right. Do not worry about using it in your application. In addition to marine I think they use it in motorhomes to watch the starting battery as well. As far as the BMV is concerned you want to program it for a 12v bank with your combined series-parallel amp hours.

[Guest]

From Victron on midpoint: You can use the Victron for a separate starting battery or the feature can be used to check midpoint voltage on a battery bank, depending on how its configured. The Aux input has several functions where I use this input for battery temperature. Looking back at the manual, if I had an expensive battery bank I might use the mid point function since a bad cell on one battery (lead acid) could kill the entire bank. Open the manual and use the keys Ctrl+F and type in Midpoint. Plenty of information in how to set this up and monitor.

https://community.victronenergy.com/...-midpoint.html

Jim

[Yoda]

From Victron on midpoint: You can use the Victron for a separate starting battery or the feature can be used to check midpoint voltage on a battery bank, depending on how its configured. The Aux input has several functions where I use this input for battery temperature. Looking back at the manual, if I had an expensive battery bank I might use the mid point function since a bad cell on one battery (lead acid) could kill the entire bank. Open the manual and use the keys Ctrl+F and type in Midpoint. Plenty of information in how to set this up and monitor.

https://community.victronenergy.com/...-midpoint.html

Jim

Jim - Thanks for the link. Lots of information there. I think I will keep it simple
ncitro Appreciate the input too.

Now to get my dimensionally large hiney into a dimensionally small pass through to add wire bracing and get wires run back to the display (Touch 50 and BMV). Where is DR Who when I need him?

Have a great rest of the week folks.
Keith