Foiled on Victron Install; Suggestions?

[ependydad]

Originally Posted by acadianbob

The Victron 700 is a very nice unit and relatively easy to install.

HOWEVER, I wound up with a big disappointment. Installed it in our new Wildcat to monitor the batteries (when dry camping) because of the residential refrigerator (est. 7 amp draw) that uses an inverter when not hooked to shore power. Got the Victron installed, started the inverter to read the refrigerator draw on the batteries; NO CHANGE.

Further investigation showed me that the inverter has a whole separate circuit off of the batteries (that I hadn't really noticed). Therefore, the Victron does not measure the draw on the batteries for the inverter.

I know, I kinda hijacked the thread but thought the OP's question had been answered.
Big disappointment.

Anyone got any ideas how to get around this issue? I'll say that the inverter battery connections are a lot larger diameter wire.

Move the negative lead for the inverter to be AFTER that shunt for the Victron. You may have to upsize the wiring between the battery and the shunt to match. But the only thing coming off of the negative side of the battery is the Victron shunt.

(battery) --> (shunt) --> (inverter on one cable + house busbar on another)

[acadianbob]

The Victron 700 is a very nice unit and relatively easy to install.

HOWEVER, I wound up with a big disappointment. Installed it in our new Wildcat to monitor the batteries (when dry camping) because of the residential refrigerator (est. 7 amp draw) that uses an inverter when not hooked to shore power. Got the Victron installed, started the inverter to read the refrigerator draw on the batteries; NO CHANGE.

Further investigation showed me that the inverter has a whole separate circuit off of the batteries (that I hadn't really noticed or anticipated). Therefore, the Victron does not measure the draw on the batteries for the inverter as the inverter is connected to the circuit that runs the rest of the trailer. (It looks like the landing legs and slides also bypass the inverter circuit.) The slides and landing legs work whether the 12 volt disconnect is in or out; likewise the inverter.

Big disappointment. Now my fancy Victron is just a voltmeter for all practical purposes.

Anyone got any ideas how to get around this issue? I'll say that the inverter battery connections are a lot larger diameter wire. I'm real nervous about messing with how the trailer is wired.

[TitanMike]

Did you install the shunt in the NEGATIVE connection to the battery?

Make sure that it's between the actual negative post of the battery and the negative cable. Make sure that there is no possible way for any ground or negative connection to be made between the shunt and the negative terminal.

I keep emphasizing that because if you merely installed the shunt in the negative connection to the converter/power distribution panel there are all kinds of other paths to ground between there and the battery.

I installed my shunt for my Victron 702 right next to the batteries and as I have a two battery bank I connected both negative posts together and connected it to the shunt. I then ran ONE wire from the shunt to the trailer frame. There is NO possible way that any power gets in or out of either battery without going through the shunt.

That's the ONLY way that monitor will monitor all draw or charging current.

In my case I added a weatherproof enclosure between battery boxes for both the shunt and a "catastrophic failure" 100 amp fuse. The shunt is in the negative path from battery to frame (Common Ground), the fuse in the positive lead that feeds everything in the trailer, both from the distribution panel or directly connected to the battery through a junction box on the frame (slide, tongue jack, etc).

If you don't want to use an exterior enclosure like I did, just find a place in a compartment as close to the battery(s) as possible to mount the shunt. Lift the negative connection from the battery(s) and attach it to the shunt with no other wires but what were connected to the negative pose. Then run ONE wire from other end of shunt to the battery post itself. From there on make all negative connections to either the frame or the terminal on the shunt that is NOT directly connected to the battery.

Think of it like counting people going into or out of a room using only one person. Unless they all have to enter or leave through ONE door, you'll never be able to count them.

[acadianbob]

Thanks for the help. I think I'm going to have to take the tops off of the boxes and map everything out. And I think I'll have to replace a smaller cable with a larger one. I see what you guys are saying; (I think).

[TitanMike]

Take a look at the install illustration that came with the victron. It should give you a good idea of what the diagram should look like.

To repeat, the easiest way to make sure nothing is bypassing the shunt is to mount it close to the battery. Move negative wire from battery to shunt and add an off the shelf negative battery cable (With lugs on both ends that get fastened to bolts) between negative terminal and shunt.

Also, make sure the connection to the battery is on the proper end of the shunt. Mounting close to the battery also makes for a more accurate point to connect the small wire with fuse in it. This lets the Victron measure battery voltage independent of any voltage drop that might occur on line feeding power panel.

[ependydad]

Does this diagram from my install help any?

[acadianbob]

Yes, that diagram helps. Thank you.

I have two black negative leads coming off of the battery. I interrupted the one that went to the trailer frame with the shunt. So, everything "working off of the trailer frame" is being measured. The inverter has the larger diameter black cable going straight to the battery. It is still bypassing the shunt.

So, here is what I believe I need to do:
1) Remove the inverter black cable and hook it to the shunt. I think it should be on the side of the shunt that currently has the cable grounded to the frame.
2) Replace the black cable from the battery to the shunt with a larger diameter cable to match that of the inverter cable. Other end of the shunt obviously.

Bottom Line. ONE cable from negative battery post to one end of the shunt. ALL other negative cables hooked into the other end of the shunt (including the one to the frame). I understand that which end of the shunt for each has to be right in order to get negative numbers for draw.

Does that sound right? I think that this is what you are telling me I should do and it seems "right" to me. (Not doubting your info. Just trying to get my head around it.)

It seems that the slides and landing legs are currently (no pun intended) going through the shunt and being measured as my amp hr draw goes up when I operate a slide. This is even though the slides and legs are not affected by the on/off battery disconnect switch. (That seems odd to me. On our last 5er, the switch disconnected everything.)

I think I'm probably going to have to make a cable as the shunt is 1/2" lug and the battery is 3/8" lug.

I have 2 Group 27s hooked in parallel. So, if I keep to the current arrangement of positive coming off of one battery and negative coming off of the other, that should be good.

[ependydad]

You got it, Bob.

You can buy battery cables from Amazon in an amazing number of combinations.

[acadianbob]

Originally Posted by ependydad

You got it, Bob.

You can buy battery cables from Amazon in an amazing number of combinations.

Didn't know that either! Never would have thought of that. Thanks.

[bubbles]

Originally Posted by acadianbob

It seems that the slides and landing legs are currently (no pun intended) going through the shunt and being measured as my amp hr draw goes up when I operate a slide. This is even though the slides and legs are not affected by the on/off battery disconnect switch. (That seems odd to me. On our last 5er, the switch disconnected everything.)

That's because, like a lot of units awning, levelers, slides, steps, etc. are fused directly off the battery. They are switch operated and therefore do not drain the battery unless actuated. Current flows from negative to positive. That is why the shunt is placed at the negative battery post so amp draw can be measured. If the shunt were placed at the positive post I think it would only reflect charging amperage to the battery. It's been awhile.

[TitanMike]

Originally Posted by ependydad

You got it, Bob.

You can buy battery cables from Amazon in an amazing number of combinations.

I just bought a crimping tool and cutter as well as bulk #4 wire and lugs.

Total cost was less than what it would have cost to buy ready made cables in varying lengths.

[TitanMike]

Originally Posted by bubbles

That's because, like a lot of units awning, levelers, slides, steps, etc. are fused directly off the battery. They are switch operated and therefore do not drain the battery unless actuated. Current flows from negative to positive. That is why the shunt is placed at the negative battery post so amp draw can be measured. If the shunt were placed at the positive post I think it would only reflect charging amperage to the battery. It's been awhile.

The only reason the shunt is in the negative feed is so the small fused wire can be connected to the positive post. Otherwise the circuit board mounted on the shunt wouldn't be fed by a complete circuit. System gets its operating power in this manner and this is where battery voltage is measured.

On a side note, many installations have several connections at the pos terminal, often high current. It's easier to deal with the single negative wire that goes off to a common ground

[bubbles]

Originally Posted by TitanMike

The only reason the shunt is in the negative feed is so the small fused wire can be connected to the positive post. Otherwise the circuit board mounted on the shunt wouldn't be fed by a complete circuit. System gets its operating power in this manner and this is where battery voltage is measured.

On a side note, many installations have several connections at the pos terminal, often high current. It's easier to deal with the single negative wire that goes off to a common ground

Not familiar with this circuit board mounted on a shunt you speak of. To me a shunt for measuring amp draw (calibrated for voltage) is basically a calibrated resistor typically inserted in series with the negative battery post and chassis ground.

[TitanMike]

Originally Posted by bubbles

Not familiar with this circuit board mounted on a shunt you speak of. To me a shunt for measuring amp draw (calibrated for voltage) is basically a calibrated resistor typically inserted in series with the negative battery post and chassis ground.

You are correct when just thinking of an ordinary shunt used with regular ammeters.
With the Victron 7xx monitors, their shunt has a small circuit board mounted on one end that provides the interface for the data cable running to the actual meter which can be mounted many feet from the battery.

Check out the Victron website and the quick install manual for their BMV 700 series monitors. The circuit board and it's position is in their graphics outlining a proper install.

[camaraderie]

Bob...sounds like you have it now. If you have multiple negative ground that are too much to attach to the shunt...you can add a multiple connection negative bus bar to the setup and then run a single feeder cable from the bus bar to the shunt to capture all the negative wires in one connection. Good luck!

[bubbles]

Originally Posted by TitanMike

You are correct when just thinking of an ordinary shunt used with regular ammeters.
With the Victron 7xx monitors, their shunt has a small circuit board mounted on one end that provides the interface for the data cable running to the actual meter which can be mounted many feet from the battery.

Check out the Victron website and the quick install manual for their BMV 700 series monitors. The circuit board and it's position is in their graphics outlining a proper install.

Victron's shunt is an ordinary shunt. Victron has developed a circuit that allows a digital readout with more parameters monitored. Remove the circuit board and attach a standard analog meter. My point is, the shunt install is still at the battery negative post and not because of any digital component wiring. I'm done. The OP should be good to go.

[CHICKDOE]

many auto parts stores also make custom battery cables on the spot. I got some at the local NAPA store.

[ependydad]

Originally Posted by TitanMike

I just bought a crimping tool and cutter as well as bulk #4 wire and lugs.

Total cost was less than what it would have cost to buy ready made cables in varying lengths.

Mind me asking for links or more info? I've debated getting the tools to buy & make cables. You're right on the cost, for my full battery installation, I think I had between $150-200 in cables.

[TitanMike]

Originally Posted by ependydad

Mind me asking for links or more info? I've debated getting the tools to buy & make cables. You're right on the cost, for my full battery installation, I think I had between $150-200 in cables.

The wire cutter and crimping tool came from Amazon

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

$33 for both tools. The crimping tool has several choices of dies for different sized wire. Yes, from China but of surprising quality. Every lug I crimped came out looking great and the tool never faltered.



Bought my wire (welding lead) and copper lugs from amazon as well. Several sources for each and you don't have to buy a 500' roll. Lengths from 10' to 50', even packaged in paired sets of red/black wire so you can keep the + and - organized.

I also bought some shrink wrap and finished off every lug with a 2" piece to seal off the junction between lug and wire insulation. Aside from the savings in cost of wire, the fact I could make a wire to the exact length I needed was nice. No having to settle for wires that were cut with lugs crimped in 6" to one foot increments.

[TitanMike]

Originally Posted by bubbles

Victron's shunt is an ordinary shunt. Victron has developed a circuit that allows a digital readout with more parameters monitored. Remove the circuit board and attach a standard analog meter. My point is, the shunt install is still at the battery negative post and not because of any digital component wiring. I'm done. The OP should be good to go.

It is in the case of the Victron shunt because of that small circuit board. Also important is the orientation of the shunt.

Since the OP has a Victron meter it's important that THAT shunt be installed correctly. If he was building or installing any OTHER system, you are correct but that's not the case, is it.