Victron BMV-712 Battery Monitor Shunt Install location

[Garfish]

Getting ready to install in Sport 22 (no inverter). Correct that I can connect negative cable from battery to the shunt and then buy short battery cable from shunt to buss as long as at least same gauge as OEM cable?

[uncle_bob]

Originally Posted by Garfish

Getting ready to install in Sport 22 (no inverter). Correct that I can connect negative cable from battery to the shunt and then buy short battery cable from shunt to buss as long as at least same gauge as OEM cable?

Hi

As long as there is only one cable leading away from the battery negative, matching the gauge of that cable is fine. If at some point you plan to put in an inverter then the cable would need to be a bit bigger.

Bob

[waninae39]

use the same or larger cable.
close to battery as possible.
dielectric grease on all connections
crimp each connector with a hydraulic crimper

[5150mike]

Originally Posted by Jimbob24

U need to install as close to battery as possible if. It directly to neg pole. My batteries are in parrallel so see pic below.

It is a multi hour job to put it anywhere else than directly to battery (per the am solar guys) so I just weatherproofed it and hooked it up and left in the battery box. Works sweet. But if you hook it up wrong the info won’t be accurate as far as time remaining , amp draw, etc

My batteries are connected just like yours, but I put my shunt inside my TT , my question is should I move the inverter wire from the negitve of the of the most positive battery too the negitve of the most negative battery,

[fran&frank]

No, your inverter wire should go directly to the supply side of your shunt, the same side that is connected to your negative bus bar. There needs to be only one wire coming from the negative side of the batteries to the input side of the shunt, nothing else.-- Frank

[5150mike]

Originally Posted by fran&frank

No, your inverter wire should go directly to the supply side of your shunt, the same side that is connected to your negative bus bar. There needs to be only one wire coming from the negative side of the batteries to the input side of the shunt, nothing else.-- Frank

Now I am confused, I have 2 negative wires coming from my batteries, one goes to the inverter and one goes to the negitve bus bar, I have spliced both wires and they now both run through the shunt, is this not correct?

[uncle_bob]

Originally Posted by 5150mike

Now I am confused, I have 2 negative wires coming from my batteries, one goes to the inverter and one goes to the negitve bus bar, I have spliced both wires and they now both run through the shunt, is this not correct?

Hi

The two negative wires should go to the "bottom" of the shunt. The "top" of the shunt goes to the batteries and only to the batteries. Any other random wire that happens to be connected to the battery negative and lead off somewhere else (it's Airstream ..... who knows ....) also needs to go to th e"bottom" of the shunt.

Bob

[fran&frank]

So If I understand you correctly you have two wires coming from the negative side of your batteries to the input side of the shunt, then on the output side of the shunt one wire going to the negative bus bar and one going to the inverter? If so thats actually OK. Having two wires from the battery to the input side of the shunt is redundnant, but if single wire is undersized maybe the two are better. Bottom line is the only thing connected to the negative side of the battery is the shunt, everyting else comes off the other side of the shunt.

[5150mike]

Originally Posted by fran&frank

So If I understand you correctly you have two wires coming from the negative side of your batteries to the input side of the shunt, then on the output side of the shunt one wire going to the negative bus bar and one going to the inverter? If so thats actually OK. Having two wires from the battery to the input side of the shunt is redundnant, but if single wire is undersized maybe the two are better. Bottom line is the only thing connected to the negative side of the battery is the shunt, everyting else comes off the other side of the shunt.

Yes that's how I have it connected, my original question was should both negative wire at the battery be connected to the same battery? Because mine are not

[waninae39]

its much easier to mount everything on plywood, pre wire as much and them mount

here is my initial plywood mount under the bed facing road side
pre and post

[5150mike]

Wow looks awesome, wanna come do mine!!

Originally Posted by waninae39

its much easier to mount everything on plywood, pre wire as much and them mount

here is my initial plywood mount under the bed facing road side
pre and post

[uncle_bob]

Hi

The shunt setup would be every bit as accurate if you had a 100' long cable between it and the battery. Cable length does not impact accuracy. A 1 foot vs 4 foot cable is no different than having one more foot run to the load in terms of efficiency. If you take a look at the stock install of the inverter cable, shortening that up would be a much higher priority than anything you might do with the cable to the shunt.

Bottom line: No, the shunt does not have to go "as close as possible" to the battery negative.

Bob

[waninae39]

i agree, small changes don't matter much
try to use as large a cable as you can

as 12v is low voltage and losses are the square of current, you want to keep the cable resistance low

[gator.bigfoot]

See this excellent article

https://marinehowto.com/installing-a-battery-monitor/

[tamifailla]

Really liked the method you used to install you Victron BMV.Much cleaner and easier. I'm going to use the same idea on my 2016 25ft. I l also have a Zamp portabl solar panel wired to my battery box.Do you think I would need to wire the Zamp negative to the battery side of the shunt?Thanks

[gator.bigfoot]

Originally Posted by tamifailla

I l also have a Zamp portabl solar panel wired to my battery box.Do you think I would need to wire the Zamp negative to the battery side of the shunt?Thanks

The whole idea of the shunt is that it is the last thing between the negative and the battery. You don't want to accidentally or intentionally create a bypass. Wire the negative as all other negatives. They must go to the shunt and not the battery. The other side of the shunt must always be alone and the only thing going to the negatives of the batteries.

By wiring the shunt in this manner you will always have a correct reading on the monitor. I realize that for portable panels this may involve some additional wiring, but it is the only the correct way. Utilizing a separate charge controller between the portable and the fixed panels will also separate the mismatch in the panels allowing you more freedom. If the charge controllers are of the same brand you can set them up to have them talking between them (depending upon the brand of course). Personally I would install the charge controllers in the RV and then just have a quick connect plug for the portable panels via a disconnect.

[farafield]

Originally Posted by waninae39

its much easier to mount everything on plywood, pre wire as much and them mount

here is my initial plywood mount under the bed facing road side
pre and post

That is so beautiful I am going to cry!

[52HalfTon]

Originally Posted by pcskier

I mounted mine in the galley near the tank monitors...I like being able to glance at the amps frequently when I pass by (without being obsessed, of course ) to see what's happening and manage my power usage as may be dictated by what kind of sunlight my panels are getting.

How did you route up into bulkhead? I can see where the tank monitor wiring comes out behind the microwave in my FC25FB but cannot fish anything through the wall and out the monitor opening.

[jwcamp]

I have installed the Victron BMV-712 Smart and everything seems to be working. I am fairly new to Airstreaming (we have had our 2019 International Serenity 25FB for a year). I am having a difficult time figuring out how to run the cat5 (I believe) cable for the monitor from the battery box (where the shunt is located) to the interior of the trailer. I see some very nice pictures of the monitor mounted in various locations in the trailer. How did you get the cable there?

[uncle_bob]

Originally Posted by jwcamp

I have installed the Victron BMV-712 Smart and everything seems to be working. I am fairly new to Airstreaming (we have had our 2019 International Serenity 25FB for a year). I am having a difficult time figuring out how to run the cat5 (I believe) cable for the monitor from the battery box (where the shunt is located) to the interior of the trailer. I see some very nice pictures of the monitor mounted in various locations in the trailer. How did you get the cable there?

Hi

The 712 is very much *not* waterproof. The battery box is going to get a wide range of water and other crud into it. Unless you have a really good enclosure just for the 712 ( = a proper hermetic box ), it's better to move it inside.

Bob