Installing a battery monitor

[B.R.Sail]

I am a long-time reader of all the great advice on this site. This is my first post as a new member, so hopefully I am doing this correctly-

I have recently installed a Victron BMV single bank battery monitor. I have a 2005 hunter 33, purchased approximately 1 year ago. I have used the advice on this site for previous upgrades and installations, such as: electric windlass, new toilet, companionway doors, etc.

The battery monitor is the first thing that has required an adjustment to the main battery cables, and as a result, I would really appreciate some feedback on my wiring to make sure I am not making any mistakes.

I researched the installation procedures for this monitor, and an article on Compass Marine was very helpful. Picture of the suggested wiring from them is attached...
My setup, however, is a little different from the picture in that I have 2 house batteries, a starter battery, and an inverter/charger. I have attached a drawing of the previous wiring on my boat, compared to the new wiring that I just setup.... (When looking at my drawing, you might come to the conclusion that I am not an electrical engineer..... And you would be correct!! Hopefully you can get what I'm trying to show)
Question 1- does my new wiring look generally correct?
Question 2- there is a small grey wire coming from my inverter and running to the negative post on the house battery. I'm not exactly sure what it is for, and as a result, I don't know if it should be left where it is, or moved to the load side of the shunt like the other cables.

Any help or guidance is much appreciated!

[Caribsailors]

Yes your new set up will work.......but here are my thoughts

"My setup, however, is a little different from the picture in that I have 2 house batteries, a starter battery"

So you have two banks, you should be monitoring both not just the one.
I'm not a big fan of the 1/2/both switches. I would suggest a single switch for each bank and a third between them to combine them if necessary. Somewhat removing the human error of the BOTH position, everyone is warned about.

I also like and use a combining relay between the banks which will separate or combine the banks from the charging source based on bank voltage. I have used Bluesea's combiner on two seperate vessels, but recently have changed my latest one out to SMARTGuage Electronics, Smart Bank and SmartGuage combo
SmartGauge Electronics - Homepage
Their site has a wealth of battery information!!!!

Just my thoughts, hope it helps.

Cheers

[B.R.Sail]

Thank you for the thoughts, and for the link you posted. I guess the rationale for the "single bank" monitor is that I am usually only at anchor on day/weekend trips. The second bank is only a starter battery, so I usually switch over to the house bank and save the starting battery. I figured a single monitor for the house bank would work for this setup. But the suggestion is a good one and monitoring the starter battery separately would probably be helpful.

[CharlieJ]

Any particular reason why you want two house banks?

As to the grey wire going to the battery negative post, I suspect that it is a temperature sensor to provide input to the inverter/charger for temperature compensation when it is functioning as a charger.

[B.R.Sail]

Maybe I didn't explain it properly- I have one house bank comprised of 2 batteries wired in parallel. The other battery is a starting battery that I usually switch off while at anchor. Does that answer your question?

[Maine Sail]

Move your start battery neg to the loads side of the shunt and you will be in good shape.. Is the small black wire from the inverter the temp sensor?

[goboatingnow]

I would not advise that you monitor the start battery and domestic using a single shunt, if you want to monitor both banks , use a dual monitor and shunts. Otherwise you cant tell whats going on.

In reality you only need to monitor the domestics.

dave

[Maine Sail]

Originally Posted by goboatingnow

I would not advise that you monitor the start battery and domestic using a single shunt, if you want to monitor both banks , use a dual monitor and shunts. Otherwise you cant tell whats going on.

In reality you only need to monitor the domestics.

dave

That is all he is doing.

With a BOTH position on-board the boat the start battery should be wired on the load side of the shunt. If not any current it takes or gives the house bank, when placed in the BOTH position (paralleled), will not get counted and the counting errors will only get worse with time.

To accurately monitor the house bank all loads or charge sources need to be on the load side of the shunt including the starting battery if it can be combined with the house bank via a paralleling switch.

[B.R.Sail]

Originally Posted by Maine Sail

That is all he is doing.

With a BOTH position on-board the boat the start battery should be wired on the load side of the shunt. If not any current it takes or gives the house bank, when placed in the BOTH position (paralleled), will not get counted and the counting errors will only get worse with time.

To accurately monitor the house bank all loads or charge sources need to be on the load side of the shunt including the starting battery if it can be combined with the house bank via a paralleling switch.

That makes sense. Thank you for the explanation, and yes, as you said I am only trying to monitor the house bank with this setup. Also, I do believe the small wire coming from the inverter is the temperature sensor.

[B.R.Sail]

Originally Posted by Maine Sail

That is all he is doing.

With a BOTH position on-board the boat the start battery should be wired on the load side of the shunt. If not any current it takes or gives the house bank, when placed in the BOTH position (paralleled), will not get counted and the counting errors will only get worse with time.

To accurately monitor the house bank all loads or charge sources need to be on the load side of the shunt including the starting battery if it can be combined with the house bank via a paralleling switch.

One additional question on this- when programming the battery monitor, I need to input the total amp hours. Would I input the total for my house bank alone (which is what I'm trying to monitor) or should I include the starter battery since the negative wire for the starter battery is on the load side of the shunt? Will the accuracy of the readings depend on whether the switch is on BOTH or 2(HOUSE)?

[sailorboy1]

Are you sure your 1/2/both/off switch has anything at all to do with your start battery?

On my Hunter that is an inverter selector switch and has NOTHING to do with the start batery. All it does is select which battery supplies the inverter. It also determines which house battery gets charged from either the engine or the charger.

So when I installed my BM I put it on the load side of both house batteries and always leave my 1/2/both/off inverter selector switch in both and supply the DC panel with both house batteries.

And programed the BM for the 2 house batteries.

[B.R.Sail]

Originally Posted by Don L

Are you sure your 1/2/both/off switch has anything at all to do with your start battery?

On my Hunter that is an inverter selector switch and has NOTHING to do with the start batery. All it does is select which battery supplies the inverter. It also determines which house battery gets charged from either the engine or the charger.

So when I installed my BM I put it on the load side of both house batteries and always leave my 1/2/both/off inverter selector switch in both and supply the DC panel with both house batteries.

And programed the BM for the 2 house batteries.

Hmmm....unless I am way off base in my understanding of the wiring (which is possible) then yes, I am sure. I followed the positive wires from the starter battery and the house battery. Starter battery leads directly to side 1 of the switch, house battery runs to side 2, and the switch runs to the main panel. Inverter only has two wires running to the batteries and those wires are connected directly to the house batteries. Nothing runs from the inverter to the switch.

Don't know if this is the manufacturer setup, or from the previous owner.

[sailorboy1]

seems wrong for a current type Hunter that you have 2 house batteries and no way to select between unless it was changed, have you asked Hunter for a diagram

[smac999]

not having read all the posts.

you need to move the neg from the starter battery to go from the starter battery to somewhere on the load side of the shunt. you'll probably need a large bus bar there after the shut. as you'll have a few large wires. inverter neg, boat neg, starter battery neg, and you also seem to be missing the inverter chassis ground which will be a 1/0 or 2/0 going to this bar was well. do you have one?

the monitor would be setup for the amp hours of the house battery only

in the pic you are also missing a switch and class t fuse on the inverter pos line.


the 1-all-2 switch setup looks ok. you have emg. power available to power the dc panel from the engine batt if needed. and can also parrellel if needed. just leave it selected to house all the time.

though I'm asuuming the engine has it's own switch and cable though? or is it coming off the common lug of that same switch? because in that case you don't have a start and house battery... you really just have 2 equal banks. there is a difference.

If so I would look at the blea see add a battery kit. change that switch and add an acr.

[smac999]

Originally Posted by Don L

seems wrong for a current type Hunter that you have 2 house batteries and no way to select between unless it was changed, have you asked Hunter for a diagram

that would be stupid of them to split up a house bank into 2.