Installing Victron BMV-712 battery monitor in 2021 T@B 400

ColoradoSun

I am planning to install the BMV-712 battery monitor in our new 2012 T@B 400 and have reviewed installs from earlier year models. I'd be very interested in hearing about the experience of anyone having done the install in the 2021 configuration. I have opened up the battery compartment to see what's what. The first problem I encountered was trying to disconnect the gas strut that is on the storage compartment just forward of the battery compartment in order to remove the battery compartment cover. There does not seem to be a removable clip that allows one end to be disconnected from the cabinet. Any ideas?

falcon1970

My TAB is buried in snow at the moment but if you have a photo of the strut I think I can tell you how it comes off.  I wouldn't think it has changed between 2019 and 2021.

falcon1970

Although SW Colorado probably has more snow than we do here in Abilene, TX.  This is the 2nd snow this year and I've got 6" in my yard this time.

Denny16

The easiest way is to remove the gas strut mounting screws inside the compartment.  Here is what you are going to find:

Not visible, but on right side of the inverter is a little black battery distribution box, with a rd and white wire coming from the battery to the black box.  Remove the white wire from the distribution box and connect it to the battery side of the shunt, and connect a wire of the same gauge (you will need to provide) from the load side of the shunt back to the battery distribution box you disconnected the white wire from.  

Here is what the battery distribution box looks like:

This is from a 2019 TaB400, but the little black distribution box is the same, just a different layout behind the battery box, now made of wood, shown in first photo above.

Cheers

bergger

Just unscrew the strut.  That's what I did when I had to correct the installation of my shunt that NuCamp improperly installed.  The install is very easy.  Here is a picture of where the shunt is installed in the compartment with the inverter.  You'll just need to get an automotive battery cable from any auto parts store.  Then connect the cables per the shunt instructions.  NuCamp completely screwed up the wiring of my shunt but with a little conformation and help on this site I was able to correct everything.  

This is showing the placement of my shunt but the wiring is not correct.  It also shows the wiring for the solar plug I added to the trailer.  



This photo shows the correct wiring on the shunt.  Black wire with the yellow cap is from the distribution block (in you outside storage compartment on the 2021) and the other black cable is the automotive battery cable (bought at Auto Zone) and connected to the battery.  Sorry I don't have a finished pic of the wiring on the battery end.  



Here's a link to the discussion I had when I first got our new trailer last spring and soon realized something was not right.  https://tab-rv.vanillacommunity.com/discussion/10722/more-questions-than-answers/p1

Denny16

So nüCamp moved the battery distribution box to inside the pax side storage locker.  You could add the shunt there between the battery and distribution box.  No need to access the battery compartment.
cheers

ColoradoSun

Thanks everyone. That should help get me started once the the unit is delivered. Here is photo of our battery compartment and the inverter. I didn't see a battery distribution box in the outside locker or the wires from the external solar plug going to the batteries but I'll look again.

rhyno

@Denny16 - wouldn't the battery still need to be accessed in order to run the B1, B2 wires?

Denny16

Yes and no, you could put b1 wire on battery distribution block, red/positive side, it just needs 12 VDC positive source.  But if you use the optional  temp sensor, or mid point b2 connection, that would require direct battery connection.
cheers

ColoradoSun

I've concluded that the battery distribution box is not located in either the battery or inverter compartments on the 2021. It maybe in a small closed compartment (under the 2X4) located between the battery compartment and the outside storage compartment. Basically behind the circuit breaker that is located in the storage compartment. See photo.

If it is in there it would be a tight fit. At least other 2021 400 owner didn't want to go there and managed to locate the stunt in battery compartment and made all of the battery-shunt connections inside the battery compartment before the battery wires exited the compartment. This required a 32" black/negative wire they used to connect the main negative battery post to the shunt block. Then the original existing black/negative wire was curled and attached to the other side of the shunt. Unfortunately I don't have a photo of that.
I haven't removed panel on the storage compartment side to look yet. I wonder if those tan colored plastic plugs  at the top of the photo just pop-out?

Denny16

Yes, this is where I was referring to in my previous post.  Also, the tan color taps just pop off, to reveal the screws, which allow removal of this panel.  So, the battery distribution box is now behind this partition between the storage locker and battery compartment.  The earlier shot I saw of this area on an early 2021, did not have the extra panel covering the battery distribution box.  You could also remove the top panel under the pax side of the bunk, to access the storage locker area.
cheers

ColoradoSun

Denny16 Thanks. I could not see that space until I removed the panel under the bed. I'll check behind that panel when I get the BMV 712 but the space may be too limited.  I later removed one of those plastic tabs on the cabin interior revealing the screws. That was easy. I also found the metal clip on the end of the gas strut that can be pried off and allow one end of the strut to be removed from the mounting bracket. 

TomCanada

I don't understand why we need the distribution block at all.  Why not just disconnect (from the negative battery terminal) the cable which runs from the distribution block to the negative terminal, connect that cable to one side of the shunt, and then connect the other side of the shunt (with an extra cable you buy yourself) to the negative terminal of the battery?  Then you don't need to go fishing around trying to find the distribution box..

TomCanada

This is what I would do (ignore the wires attached to the shunt in the drawing - I commandeered bergger's photo and as he confirmed, they're not correct in that image.  Just look at my 4 step mods):

I'm curious - there might even be room to squeeze in the shunt into the battery box - though it would be tight.  I'll check for that option when I do this myself in a couple months..

bergger

TomCanada,  that's what I did except I did not drill a new hole for the new negative battery cable.  I just enlarged the existing hole a little and ran it through there.  I also attached the negative zamp cable to the shunt so there is only one cable from the negative battery terminal to the shunt.  All other negative connections are on the load side of the shunt.  You may be able to put the shunt in the battery box instead of the inverter box but it would be tight.  Plenty of room on the inverter side so might as well just put it there.  

Denny16

Either way will work.  On the late 2018 and 2019 the battery was in the sealed ABS box, so using the distribution box connection shown in my first post was the best option in this setup.  You just need to be sure all the negative load connections are on the shunt, and then just have the shunt connection to the battery.  Locating the shunt as shown above is probably better than inside the battery box, due to possible heat build up around the shunt, which needs some air space around it, per Victron.
cheers