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Old 04-22-2019, 01:52 PM   #11
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Well (insert sarcasm emoji here). Tech is an electrical guru and therefore follows the path of least resistance ??

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Old 04-22-2019, 02:14 PM   #12
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Double check the wiring for the ME-BMK monitor??

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Old 04-22-2019, 03:55 PM   #13
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Well (insert sarcasm emoji here). Tech is an electrical guru and therefore follows the path of least resistance ??
Ohm my, an electric joke.

I honestly believe that there is something to what the tech is telling me as I don't think he's the sort to shine me on to avoid making a fix. If I lived closer he'd be happy to work with me to resolve this, but I don't have any desire to drive the 13 hours to Huntington, IN for such a non-critical issue. I'm just having trouble understanding how the shunt can work as wired and since it isn't working and the wiring doesn't match the manual, it's worth it to me to explore that.

I may have to resort to driving out there for service if I can't fix the issue on my own though.
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Old 04-22-2019, 06:12 PM   #14
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Tech is wrong. As I have said previously move inverter ground to the same side as vehicle frame ground. The shunt is between all loads and battery, So you should not see any other cable going to the battery ground except the one from the shunt.

When you try to test you don't need to go to SOC, just look at current. If hooked up correctly, you will see the current change based on load.

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Old 04-22-2019, 07:07 PM   #15
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I should rephrase my answer, the Tech is confused, but correct. SMB north did install some battery monitors wrong. They would have the inverter go to one side of the Shunt and have the battery and frame ground on the other side. This would allow all current to and from inverter/charger to be read. Unfortunately all devices that negative paths were through the frame did not go through the shunt. So the SOC meter go confused because it wasn't depleting as fast as it should have. In your picture if you look above the frame connection there is probably a terminal bar that has ground connection from various devices , refrigerator , water pump, etc. Let alone they also use frame as a grounding via a sheet metal screw in many places.



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Old 04-22-2019, 08:03 PM   #16
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I should rephrase my answer, the Tech is confused, but correct. SMB north did install some battery monitors wrong. They would have the inverter go to one side of the Shunt and have the battery and frame ground on the other side. This would allow all current to and from inverter/charger to be read. Unfortunately all devices that negative paths were through the frame did not go through the shunt. So the SOC meter go confused because it wasn't depleting as fast as it should have. In your picture if you look above the frame connection there is probably a terminal bar that has ground connection from various devices , refrigerator , water pump, etc. Let alone they also use frame as a grounding via a sheet metal screw in many places.



-greg
Yes, I am certain that there is a reason for the tech to think that this is the correct way to connect the cables to the shunt and it likely does have something to do with the way the grounds are connected. I do wish Sportsmobile did a better job at documenting all these changes; it may serve to head off some of these issues.

I don't have a grounded bus bar in this compartment. I bet there is one in the electrical services cabinet above my galley. That is where my 12 volt master cutoff is, along with the 12 volt fuse box and the 120 volt circuit breakers. I've attached a photo better showing the cabling in the compartment with the batteries and inverter. You may note one odd switch and inline fuse in the lower right of the photo. That is to turn off the hardwired exhaust fan for the composting toilet. I had them wire that to the battery bank so I can leave the composting exhaust fan on even when I cut the 12 volt master switch in the van.

It was pouring rain here today so I didn't spend any time tinkering with the van. I plan to make the shunt connection changes tomorrow. Once I've made them I'll monitor the reported current draw as I turn on loads in the van, as you suggested.

I did note the connection of the battery monitor wires to the shunt; currently the blue wire is connected to the left side of the shunt (same side as ground) and the orange wire is connected to the right side of the shunt (same side as where the battery and inverter are currently connected).

This connection would be correct if I moved the negative battery connection to the left side of the shunt, but in your diagram you state that the negative inverter connection should be moved to the left side of the shunt (where the ground is now connected alone).

Is there a reason why you believe I should be moving the inverter connection instead of the battery connection? Is it better to have the vehicle ground on the load side (inverter side) or the battery side of the shunt? If I am to move the inverter connection I'll need to swap the placement of the blue and orange wires so that the blue wire is correctly placed on the battery side of the shunt.

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Old 04-22-2019, 08:08 PM   #17
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Double check the wiring for the ME-BMK monitor??

Diagram:
Attachment 26847
Yup, I did check that in the beginning thinking that would be an easy fix if it were wrong.

Currently, the blue wire is on the left side of the shunt (as pictured in my photo) and the orange wire is on the right side. This would be correct if the battery connection were moved to the left side as then the blue wire would be on the battery side of the shunt.

As it is now, the blue wire is on the vehicle ground side and the orange wire is on the side with both the battery and the inverter (load). That can't be correct; both the battery and load are on the same side of the shunt.
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Old 04-22-2019, 08:55 PM   #18
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For the shunt to read current is has to have a path through it. Moving the inverter to the same side as the frame makes the current flow through the shunt, that way also any current flowing through frame needs to go through the shunt to get to the battery. From this photo I don't see any other ground attachments other than the frame and inverter. That would lend me to think that all the other devices are attached somewhere to the frame, so their current path would come from the frame to through the shunt to the battery. You have to look as the frame as a big bus bar. So the frame is the load side, so the inverter and frame need to be on the same side.

They could have messed up the blue -orange polarity while the were at it. That should be easy enough to figure out, if your not charging you should only see negative current reading. Sounds like they did from your post.

I know that we are conditioned to thinking ground of the battery goes to the frame. But, if you didn't have the inverter it would be easier to see that the shunt needs to go between the frame and battery. The polarity being wrong (twisted blue-orange wires) probably is the reason you didn't see a charge from the alternator, it was reading it as a discharge not a charge.

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Old 04-22-2019, 09:50 PM   #19
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Sounds like the battery monitor leads are also wrong. Double check the terminal 1 and 2 - Blue to T1, orange to T2. The manual says to be careful on those connections.
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Old 04-22-2019, 10:52 PM   #20
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For the shunt to read current is has to have a path through it. Moving the inverter to the same side as the frame makes the current flow through the shunt, that way also any current flowing through frame needs to go through the shunt to get to the battery. From this photo I don't see any other ground attachments other than the frame and inverter. That would lend me to think that all the other devices are attached somewhere to the frame, so their current path would come from the frame to through the shunt to the battery. You have to look as the frame as a big bus bar. So the frame is the load side, so the inverter and frame need to be on the same side.

They could have messed up the blue -orange polarity while the were at it. That should be easy enough to figure out, if your not charging you should only see negative current reading. Sounds like they did from your post.

I know that we are conditioned to thinking ground of the battery goes to the frame. But, if you didn't have the inverter it would be easier to see that the shunt needs to go between the frame and battery. The polarity being wrong (twisted blue-orange wires) probably is the reason you didn't see a charge from the alternator, it was reading it as a discharge not a charge.

-greg
You are correct that I'm used to seeing a vehicle ground connected with the negative on the battery bank, not the inverter. I wouldn't think to associate the vehicle ground with the load side, but it makes sense.

I'll move the negative cable from the inverter as you suggested. I'll have to temporarily unscrew the shunt from the floor so that I can access the terminals where the blue and orange wires are attached; the way the shunt is installed those terminal connections are right up against the wheel hump.
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