Victron BMV-712 install

Jul 27, 2017
44
Catalina 30 5167 Texas
This might prove to be a silly question, but I bought a Victron BMV-712 Battery Monitor and I am getting prepared to install it.

I have 2 batteries:
batteries.jpg


The negatives are connected together, the positives go to a Perko 1/ALL/2/OFF switch:

elec-panel.jpg

The B1 wire on the shunt is supposed to go to red on the battery:
monitor.JPG


The negative side is obvious, but where would the B1 wire go in my situation?
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
The negative side is obvious, but where would the B1 wire go in my situation?
To the battery you use as your house bank. The second one (B2) only measures voltage, not aH. Have you RTFM?
 
Jul 27, 2017
44
Catalina 30 5167 Texas
Thanks Stu, I have R'd the FM. Unfortunately the FM included in the BMV-712 only covers operation and not connection. It does come with a fold-out style quick guide, which is where the picture came from. Since I have two batteries and my switch is typically set to all, it would make sense to me to wonder where the B1 cable would go. My sincerest apologies for wondering about that.

Allow me to rephrase my question...

Does anyone have a Victron battery monitor in a two battery situation where the two negatives are connected together, with positives going to a Perko 1/all/2/off switch, typically set to ALL, and if so, where did you connect the B1 cable?
 
Sep 25, 2008
957
Macgregor & Island Packet VENTURE 25 & IP-38 NORTH EAST, MD
If you always keep the switch in "all", then put the B1 to the "all" post on the switch. You will then be monitoring both batteries as one bank, but if you put the switch in 1 or 2, the monitor will
not give accurate info. You will also not get a reading in the "off" position. This setup, although not optimal, will work. So you don't have a reserve battery?
 
Jul 27, 2017
44
Catalina 30 5167 Texas
Thanks THECUSCUS, that is logical. I was not sure if anyone else had run into that and had come up any clever workarounds. Right now I only have the two batteries and they are configured as shown.

It makes sense to add a third battery, or to reconfigure the two I have, I just have not gotten around to it yet. We are on an inland lake and our marina is the TowBoatUS base at the lake, and we are on shower power more than not, so it hasn't really been a priority before now, due to all these "security blankets". Through the keen advantage of hindsight though, I wish I had addressed it earlier.

Thanks again!
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Since I have two batteries and my switch is typically set to all
So that changes everything, 'cuz you only have one bank, based on this new info of how you operate your electrical system..

I'd tie them together with wiring in the battery box and lead them to switch position 1, and use the Victron to monitor the bank. Then get a small start bank and put it on switch 2. Given how you operate, maybe no hurry for you. By doing this the Victron's always powered, rather than going to the switch C post.

Good luck.
 
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
A big :plus: for what @Stu Jackson says. He knows his stuff.
I have 2 12 V batteries in parallel with the Victron showing the status. It has been great for the past year.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Read these two articles, one on physical installation and one on how to properly program your monitor. You may find it helpw you understand better how they actually work and what things are critically important.. Do not rely on the BOTH setting for monitoring two batteries. They should be hard wired together in parallel if you want to monitor them both.

Installing a Battery Monitor (LINK)

Making Your Battery Monitor More Accurate (LINK)
 
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
I was about to give the same comment as MS. If you are running the two batteries as one bank using the battery selector switch then you should rewire your bank. Actually make it one bank that only runs through the Battery 1 post or replace the selector switch with an on/off switch. With the batteries setup and running the way you are then you won't get a good reading on your battery monitor anyways.
 
Jul 27, 2017
44
Catalina 30 5167 Texas
Thanks again everyone. Marinehowto.com is typically my first stop when researching anything. I read those articles a while back before I bought the Victron. Excellent site.

Getting the electrical in order and perhaps doing the wiring harness upgrade will be a good cooler weather project.
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
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Jul 27, 2017
44
Catalina 30 5167 Texas
Roger that Stu! You are the second person this week to remind me how important that is. It was actually the first project I was going to do when we bought our boat, but somehow it got shuffled away.

I just ordered the following parts and will move this up the list to the top.

Engine Wiring Harness Upgrade Kit (Item#: Z2758)
Engine Wiring Harness 18' Extension Replacement, Diesel (Item#: Z3477)
Engine Instrument Voltmeter (Item#: Z2652)

Thanks once again
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Engine Wiring Harness 18' Extension Replacement, Diesel
If the wires are good, and they usually are, you can save this cost. Read the Critical Upgrades, there are a number of follow-on items about this.
Good luck.
 
Jan 31, 2012
56
Catalina 30 mkIII Santa Barbara
I am upgrading my battery system. I am using two Trojan T-1275 batteries for the house bank wired to switch 1 on the DC master switch and a Interstate group 78 car battery with 800 CCA wired to switch 2 on the DC master switch as the start battery. I have two 100 watt solar panels that I use when at anchor that are connected to the house bank only. I was told I should get a Blue Sea ACR 7610 to prevent discharging the start battery. If I switch to position 1 when as anchor I would think this would isolate the start battery. Is this true? I am also adding a Victron BMV 700 to monitor the house bank. I would greatly appreciate your valuable input.
Greg
 

Ward H

.
Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
If I switch to position 1 when as anchor I would think this would isolate the start battery. Is this true?
Yes, this is true.
It sounds like your going to be starting on battery switch position #2, then switching to position #1 while sailing or being anchored?

Here is an easier way, promoted by Maine Sail. It is how I set up my system.
Use your house bank for house use AND starting the engine. Consider the car battery as an Emergency Reserve battery. Keep it in reserve in case you accidentally deplete the house bank.
This is where the Blue Sea ACR comes into play. It connects between the house bank and reserve bank but keeps them isolated unless it sees a higher voltage from a charging source. Then it connects the two banks to keep the reserve battery topped off. After the charge source goes away and the voltage drops past a certain point, it again isolates the two banks. This keeps your reserve battery from being drained by house use and it is always ready to be used.
Without the ACR, your charger is somehow connected to both battery banks. Either by setting the selector switch to both or wiring it to both banks. The problem is most battery charges that provide outputs for multiple banks have those outputs connected together internally so both banks are connected together.
Hope this helps.
 
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Jan 31, 2012
56
Catalina 30 mkIII Santa Barbara
Thanks Ward. So I will wire the ACR between the positive terminal on the start battery. Should I install a breaker or fuse on the positive terminal for both the house bank and the start battery?
Greg