Where do my battery cables go? - BMV-712 install

MichBadger · 12-31-2020, 01:50 PM

In my DS2860, I have two batteries under the step. I see the cables going out the left side but did not crawl underneath on my snow covered driveway to try an figure out where they go next. I pulled the mattress and looked underneath by the fuse box and mysterious electrical gizmos but did not see an obvious pos and neg wire coming in.

I have a new Victron BMV712 to install and would like to install both the shunt AND the monitor. (Yes, I know about the bluetooth but would still like the quick check capability of mounting the monitor.) I found one install with the shunt inside the battery box and the monitor cable coming out the front of the step. I'm trying to find any other alternatives where the cable would be completely hidden and thought that could be at the other end of those battery cables. Any suggestions?

MR.M · 12-31-2020, 01:59 PM

Find your converter and 12v power fuse panel and there you will find your cables

CHICKDOE · 12-31-2020, 02:31 PM

the battery ground cable could go out from under the steps and then be connected to the chassis ground. it may not actually fun to the fuse panel. i don't know this for you but on our trailer that is the way the ground cable is run.

Chuck_S · 12-31-2020, 02:31 PM

Victron is a brand name. Whatcha trying to install, could be one of a couple dozen devices?

-- Chuck

MichBadger · 12-31-2020, 02:37 PM

Quote:

Originally Posted by Chuck_S

Victron is a brand name. Whatcha trying to install, could be one of a couple dozen devices?

-- Chuck

It is a Victron BMV-712 battery monitor. I had it in the title but maybe it doesn't show up on phones.

Chuck_S · 12-31-2020, 02:41 PM

I must have missed it. I have a Trimetric amphour meter and only the shunt needs to be connected directly to the battery and separate wiring harness goes to the shunt. All connections are at the battery so there was nothing to trace. I'm assuming you can find the battery.

-- Chuck

**ependydad** · 12-31-2020, 02:43 PM

You'll want to install the BMV off of the negative post from the battery. It needs to be there to capture ALL input/output from the batteries. There are too many other places where things are grounded to the frame of the RV that you may/will miss some.

Duckogram · 12-31-2020, 06:15 PM

Your cables go to the Battery Control Center (BCC). It should be located on the left side of your 1st step well. You will find the Battery Isolation Manager (BIM) and distribution solenoid there as well. I do not think the cables themselves actually enter the BCC but are attached to a terminal lug.

Trace away, then attach the shunt to the battery is my best advice.

TitanMike · 01-01-2021, 01:25 PM

Quote:

Originally Posted by ependydad

[B]You'll want to install the BMV off of the negative post from the battery.[b] It needs to be there to capture ALL input/output from the batteries. There are too many other places where things are grounded to the frame of the RV that you may/will miss some.

Just to clarify, only the shunt needs to be next to the battery. Also the positive wire to the shunt which is connected to a positive terminal to provide power for the BMV-712. The "meter" can be mounted anywhere and you just run the cable to the shunt.

The BMV-712 should have come with a quick setup chart with pretty clear graphics. If not, here's one:

https://www.victronenergy.com/upload...tion-guide.pdf

Just make sure that all battery grounds are attached to the shunt and only a single connection continues on to the chassis ground.

camaraderie · 01-01-2021, 03:08 PM

Titan Mike has it right BUT if you have a bunch of negative wires from loads on your negative battery terminal they will ALL have to be removed and then attached to one side of the shunt (load side). If there is NOT enough room/space to connect all your negative wires there...then you can mount a bus bar and attach all the negatives to that....then run one negative from the bus bar to the shunt load side.

https://www.amazon.com/dp/B07C6524M4...ing=UTF8&psc=1

**ependydad** · 01-01-2021, 03:34 PM

Quote:

Originally Posted by camaraderie

Titan Mike has it right BUT if you have a bunch of negative wires from loads on your negative battery terminal they will ALL have to be removed and then attached to one side of the shunt (load side). If there is NOT enough room/space to connect all your negative wires there...then you can mount a bus bar and attach all the negatives to that....then run one negative from the bus bar to the shunt load side.

https://www.amazon.com/dp/B07C6524M4...ing=UTF8&psc=1

Do this. It’s a nightmare to stack 3-5 cables! I waited way too long to get a bus bar and I was completely gobsmacked at how much easier it made things.

mlmay12 · 01-01-2021, 05:40 PM

Here is how I ran mine. I only had two negative cables to worry about, one to the inverter and the other to chassis ground. The shunt power wire went on the Pos terminal next to the shunt. The hard part for me was routing the wire to the Indicator. I ran it out the bottom of the step well then back in close to some molding on the right side. Then up behind the plastic molding and across to the indicator. I didn't want to remove a bunch of panels and risk damaging them. All grounds have to go through shunt. Works well.

MichBadger · 01-01-2021, 06:00 PM

Thanks all.

I did get it mounted today. I mounted the shunt into the battery box under the stair. No need for a bus bar at this time.

I ran the communication cable out of the battery box, and up through the floor by where the propane line goes through to my furnace. It did take me more time than it should have to get the fish tape in position to grab it. It would have been easier with a second person.

Here's a pic of the finished mount. I should have been thinking further ahead and ordered a black finish but think it still looks good. Now I have to set it up and figure out how to use it.

camaraderie · 01-01-2021, 06:48 PM

Nice clean install! Have fun letting it train you...LOL ...

MichBadger · 01-02-2021, 09:42 AM

I haven’t found a great answer for this question while I am setting up the monitor so I will ask it here. I have two new interstate deep cycle batteries rated at 88 amp hours per the manufacturer. So total capacity should be 176 hours. I will conservatively take 10% off and go with 160 hours as my total capacity for now.

Since I’ve read that deep cycle batteries should not go below 50% charge, does that mean I really have 80 hours of total usage and should put that into my total capacity so it calculates battery percentage and time left, etc based on that number?

Duckogram · 01-02-2021, 10:54 AM

It is actually not that complicated if you look at it from a supply vs demand aspect. Since you have a nice Victron I would just plug in the rated Ah capacity and let the monitor tell me what the battery state is. As you already read, it is not conducive to long battery life to go below 50% but if you reduce the capacity value you are short changing the supply side of the equasion. I also really do not pay much attention to percentages. To me it is all about the voltage. In resting state I stay above 12.0 volts. At 12.0 volts I plug in, deploy solar or run the genset.

camaraderie · 01-02-2021, 11:39 AM

Quote:

Originally Posted by MichBadger

I haven’t found a great answer for this question while I am setting up the monitor so I will ask it here. I have two new interstate deep cycle batteries rated at 88 amp hours per the manufacturer.

Mitch...where are you getting 88 amp hours from? I just checked the Interstate website and there is no standard size deep cycle with that amount of amp hours which is what led me to the site as I've never seen that number. FWIW...their group 24 has 72 amp hours so you would enter 144 on the Victron set up and it will tell you when it is down to 72 or 50%.
Their group 27 has 90 amp hours...group 31 is not specified but I would guess 105. No need to take 10% off the top.

TitanMike · 01-02-2021, 11:54 AM

Quote:

Originally Posted by MichBadger

I haven’t found a great answer for this question while I am setting up the monitor so I will ask it here. I have two new interstate deep cycle batteries rated at 88 amp hours per the manufacturer. So total capacity should be 176 hours. I will conservatively take 10% off and go with 160 hours as my total capacity for now.

Since I’ve read that deep cycle batteries should not go below 50% charge, does that mean I really have 80 hours of total usage and should put that into my total capacity so it calculates battery percentage and time left, etc based on that number?

With a BMV 712 just set it for the total battery bank size. Then set the alarm to go off when you reach 50% SOC (or DOD). It will then chirp until you recharge or merely silence the alarm by pressing any button on the meter.

The Monitor is calibrated for both a Zero Current state and a 100% SOC (synchronization). The time remaining calculation will be automatically set by whatever SOC you set the alarm for.

If you want to see how much total time is remaining just don't set an alarm (use a -0- setting). You'll then have to monitor SOC regularly to avoid going below 50% SOC.

TitanMike · 01-02-2021, 11:58 AM

Quote:

Originally Posted by Duckogram

It is actually not that complicated if you look at it from a supply vs demand aspect. Since you have a nice Victron I would just plug in the rated Ah capacity and let the monitor tell me what the battery state is. As you already read, it is not conducive to long battery life to go below 50% but if you reduce the capacity value you are short changing the supply side of the equasion. I also really do not pay much attention to percentages. To me it is all about the voltage. In resting state I stay above 12.0 volts. At 12.0 volts I plug in, deploy solar or run the genset.

That works for FLA batteries. If you ever go to Lithium, or anyone reading this has Lithium batteries, Voltage means very little. The "Voltage Curve" in the Lithium batterys is practically flat with the voltage from fully charged to <10% is only a couple tenths of a volt. With them you pretty much HAVE TO pay attention to percentages or you won't have a clue as to how much power is remaining.

TitanMike · 01-02-2021, 12:02 PM

Quote:

Originally Posted by camaraderie

Mitch...where are you getting 88 amp hours from? I just checked the Interstate website and there is no standard size deep cycle with that amount of amp hours which is what led me to the site as I've never seen that number. FWIW...their group 24 has 72 amp hours so you would enter 144 on the Victron set up and it will tell you when it is down to 72 or 50%.
Their group 27 has 90 amp hours...group 31 is not specified but I would guess 105. No need to take 10% off the top.

According to some information posted online, mostly from those who use them for trolling batteries, an Interstate Grp 31 Deep Cycle (not dual purpose starting/deep cycle) can be as high as 120 ah.

I used to have two of these and based on hours of use and known loads they seemed to be pretty close to that number.

You may also like: