Victron bmv 600 battery monitor help

[galynd]

I installed a victron batt monitor on friday night. saturday, I sailed approx 8 hours without starting the engine on sat, then again on sunday, after plugging in sat night. The monitor readings never fell below 12.5 volts, current usage (I) was always approx -.63 (except when I turned on nav lights, steaming light, anchor light and deck light). Then it only dropped to -.80. The state of charge never fell below 99.8% and the Time to go never fell from 240 hours.

My house bank is composed of 2 group 27, 115 amp hour batteries. the only setup I adjusted was to set the max aH to 230.

so while running the autohelm 4000, gps, depth gauge, 4 lights and speedometer why such readings? The voltage was correct based on another volt meter. I know my current usage had to be greater than -.80?? etc...

 

[Don S/V ILLusion]

please explain how it was installed, shunt location, etc...

 

[galynd]

shunt is connected to battery with 19 inch 4 gauge cable. previous ground cable is connected to shunt. Other than that I connected supplied pos wire with inline fuse directly to batt and connected cable (looks like telephone wire) is plugged into gauge and shunt.

 

[Stu Jackson]

Don's right, you must be absolutely sure that everything is run through the shunt. Is it a (-) shunt?

You're right that you should have had more draw. Forget the voltage for no, watch the amp hours and read the amps used, like you have, when you're all powered up.

 

[galynd]

Yes, it's a neg shunt. I checked and rechecked my hookup, which is pretty simple. When running the motor or plugged in the amp charge went as high as near +20 under power (100 amp alternator) and around + 5 plugged into shore power. I know they take time to self adjust but I didn't think amp usage would make a diff.

 

[Deadhead]

The Victron has variables (amp-hr capacity and several other constants) that should be input for your specific battery during the initial calibration. Once you have input those variables (I found the manual to be fairly straight forward for this task), and ensured that the battery bank is fully charged you need to reset the monitor. After that you should be able to scroll through the screens and see the instantaneous amperage draw, amp hrs used, amp hours remaining, etc.

I agree that the installation wiring is straight forward. So, if that is correct, the calibration must be off.,

 

[galynd]

thanks deadhead and all. I thought i read the monitor would calibrate itself in time. I'll try again when I can get back to the boat. again, thx.

 

[Maine Sail]

Keep in mind that nothing, nada, zilch can connect to the battery ahead of the shunt. If it does it will not be read. It should go;

Battery post (with NOTHING else on it but the gnd jumper), ground wire jumper, shunt, system grounds

Installing grounds ahead of the shunt is perhaps the #1 reason for a batt monitor not working properly. Where does your panel ground go to and where is it currently connected?

 

[galynd]

Thanks Maine Sail. I was hoping you'd jump in. By "panel ground," I assume you mean the house bank switches/fuses? I'm not at boat but I believe it's connected to the block. The only thing connected to the battery neg is the other neg batt cable from the other batt of the same bank (jumper cable). From the batt the cable goes to the shunt, then the other cable to the block (this cable was previously connected to batt). do neg cables before and after shunt have to be same gauge? one is 4 gauge and I believe other is 2 gauge.

 

[Stu Jackson]

It's not the gauge, it's the wiring. Reread what MS said: EVRYTHING must go thru the shunt. Draw a diagram.

It sounds like you've got stuff going around the shunt --- anything that has power needs to have its negative go thru the shunt; anything that has its (-) going to the engine won't get read.

Oh, read the manual again and again and again. How do I know???

Here's one: like, MS says:

See Reply #23, here: http://c34.org/bbs/index.php/topic,4623.15.html

My Freedom Inverter Charger negative wire is run to the NDP (negative distribution post - which is a Blue Seas Power Post Plus). I put this in in 1998, well before I installed the Link 2000 and the shunt.

The monster 2/0 wire from the Freedom goes to the NDP. The shunt is connected to the NDP. The NDP goes to the engine ground.

The Freedom charging is correctly read on the Link 2000.

The wire from the shunt to the NDP is not 2/0, it's only #4 (maybe I upped it to a #2 more recently), one of the two paralleled #4 grounds, as noted on the diagram.

The system works just fine.

The reason it works is that you have to follow the flow of electrons. The charger's output power goes to the house bank PDP, through the battery bank, then through the negative of the house bank to the shunt, to the NDP and to the engine ground. The shunt reads it all, since there's nowhere else for the electrons to flow. Each of the individual banks goes to the shunt's individual #1 and #2 posts and then on to the NDP.

This wiring scheme is shown on the Link 2000 manual wiring diagram on the Xantrex website.

It's hard, if not impossible, to run a 2/0 wire from the Freedom to that shunt. The NDP is a lot easier and a lot easier to run a smaller wire to the shunt. A shorter smaller wire will have minimum impact on the overall voltage drop, of course it should be sized for the load, but based on the very, very short length.

NOTE: I need to check that diagram because I recall that I ran the 2/0 Freedom positive to the PDP and not to the battery itself. I'll update the diagram if I find it's wrong, but it really doesn't change the concept, since the PDP and the battery + post are the same electrically, only different ends of a very short wire.

I checked, it's like the diagram.

 

[Maine Sail]

Below is a photo of my battery compartment distribution panel. If you look at the shunt (yellow lines / ignore red for now) you can see that out of the top stud it simply goes to the battery with a single jumper cable. NOTHING else connects to my batteries ground in between the shunt and battery post just like the drawing above. ALL GROUNDS MUST PASS THROUGH THE SHUNT.

ALL grounds come out the bottom of the shunt (load side) and are connected to the ground buss bar which is connected to the bottom side of the shunt so that the shunt can measure the loads. If you were to connect ANYTHING to the top stud or the battery you would by-pass the shunt and it would never be seen or measured.

 

[galynd]

So Mainesail.... Per your diagram all neg cable should connect to the load side of the shunt?? Does that mean nothing should connect to the block except the cable from shunt? The only cable/wire currently connected to the load side of the shunt is the cable to the block.

 

[Maine Sail]

So Mainesail.... Per your diagram all neg cable should connect to the load side of the shunt??

Yes!!

Does that mean nothing should connect to the block except the cable from shunt?

Ideally you want one wire connected to the block that is the sum/common of all grounds.

The only cable/wire currently connected to the load side of the shunt is the cable to the block.

Here lies your problem and is probably why the alt is reading, but not much else. Because your alt is likely case grounded to the engine it is being read by the shunt and the engine ground cable is allowing that alt circuit/gnd to read through the shunt.

This is why I use a ground buss bar. Every on-board ground connects to the buss bar then one large gauge wire goes over to the engine block from the buss bar thus everything connected to the buss bar is grounded to the engine and is coming off the load side of the shunt.

Every ground, engine, alt, DC panel, batt charger, inverter, bilge pump. solar, wind generator etc. etc. on and on MUST be connected to the load side of the shunt just as I drew above...

 

[galynd]

Excellent. thank you Mainesail. can't wait to get back to the boat this weekend to make those changes.

 

[John]

maybe solved my problem?

According to this diagram, the negative from the battery on the right goes through the shunt and the positive from the one on the left goes to the battery switch (and wherever else). I will have to check, but if I'm not mistaken the way I've wired up my monitor is that, in effect, the positive from the battery on the right goes to the switch. Would that cause the monitor to fail to properly read recharged batteries (i.e., it doesn't show when amp hours go back up)?

 

[Chuckbear]

The switch connection should not have any affect on your monitor reading. You might consider moving all of those ground connections off the shunt and to a ground strip with only a single cable on the load side of the shunt. Chuck

 

[Mike B]

Re: maybe solved my problem?

John, not sure you have the same issue I did but make sure you have the shunt installed with the correct polarity. The shunt has a + and - marked on it. If you have it in backwards power coming out of the battery will show as a + and power going in as a - plus it wont count usage correctly.

 

[Chuckbear]

John, not sure you have the same issue I did but make sure you have the shunt installed with the correct polarity. The shunt has a + and - marked on it. If you have it in backwards power coming out of the battery will show as a + and power going in as a - plus it wont count usage correctly.

Good point, but mine did not have a plus or minus but a B for battery and L for load. Chuck

 

[John]

nope

John, not sure you have the same issue I did but make sure you have the shunt installed with the correct polarity. The shunt has a + and - marked on it. If you have it in backwards power coming out of the battery will show as a + and power going in as a - plus it wont count usage correctly.

I have an extra shunt at home here that is identical. One side has on it:
"50 mv
"Deltec"

The other side has:
"500 AMP
"MKB C 7'07"

There is nothing identifying which side is for battery. The only other thing is this: There are two little screws, one on either side of the shunt on its face. They are to receive one of the wires that goes to the monitor. If I'm remembering correctly, I screwed that wire into the side away from where the battery cable is attached. Is that right?