Victron Smart Shunt Not Measuring Charge Current?

[Alphabavo]

The switched MOSFET's are connected between B- and P- so when you short the B- to P- the switched MOSFETs are bypassed that is why you get the current to flow, then when you remove the jumper the current stops flowing because the switched MOSFET's are not turned on by the BMS circuit.
I do not know which DALY BMS you have, but here is the link showing how to reset the Smart DALY BMS.

DALY BMS Issue BMS P- voltage = 8v vs. terminal voltage = 13v

Hi everyone, My setup: BMS: DALY BMS 4S 12V 120A Cells: 277ah ETC My issue: When multimeter connected at P- on BMS and main positive it reads a very low voltage: around 8.36v (see pictures) Although when multimeter connected directly on the main positive and main negative it reads 13.36v...

diysolarforum.com

I have the non-smart 250amp BMS with a fan.

 

[Alphabavo]

The switched MOSFET's are connected between B- and P- so when you short the B- to P- the switched MOSFETs are bypassed that is why you get the current to flow, then when you remove the jumper the current stops flowing because the switched MOSFET's are not turned on by the BMS circuit.
I do not know which DALY BMS you have, but here is the link showing how to reset the Smart DALY BMS.

DALY BMS Issue BMS P- voltage = 8v vs. terminal voltage = 13v

Hi everyone, My setup: BMS: DALY BMS 4S 12V 120A Cells: 277ah ETC My issue: When multimeter connected at P- on BMS and main positive it reads a very low voltage: around 8.36v (see pictures) Although when multimeter connected directly on the main positive and main negative it reads 13.36v...

diysolarforum.com

I have the non-smart 250amp BMS with a fan.

 

[Randij]

I expect a need to fully understand what is happening in the citcuit. Its really useful to carry out a little background reading on electric circuits. Internet search engines can help here.

I think the main confusion is that the BMS is regarded as a circuit component, instead, you need to consider the { cells and the connected BMS assembly } to be the 'battery'. Nothing else should be connected inside this 'battery'

The shunt is inserted in the negative path from the 'battery' to the negative buss bar.

The main protective fuse for the battery is placed as close as practical to the battery positive connection, the cable from the fuse connects to the positive buss bar.

Everything else, chargers and loads, are connected to the buss bars.

Victron tried to help by providing instructions with the smart shunt. The battery in this illustration, if lithium type , would have the BMS inside the grey box.
View attachment 50770

Mike

This diagram works . Battery (even if BMS is inside battery) to shunt to everything else. Do not put anything between the neg pole of the batterit’s and the shunt. Very important

 

[Geokilroy]

Howdy, All!

I've been working on building a small system, just to get my feet wet before I go all in. I have everything working so far, with the exception of my Victron Smart Shunt. The shunt measures everything except the charging current. I can watch the battery voltage increase slowly as it charges on the monitor, but there is no corresponding indication of current flow, and the historical tab shows 0 historical charge current. I have it installed as directed, as far as I can tell, and will include pictures. Thoughts?


View attachment 50718

Just looking at this pic, why is the BMS going to the load side of the shunt? I thought the BMS should be on the battery minus of the shunt. Isn't the BMS the last output of the battery? Isn't the shunt hooked up backwards in the pic?
Please help me understand my thinking.

 

[Randij]

The shunt goes immediately after the battery negative and next, the inverter negative in series along the negative. The shunt works by looking at the small current in the shunt along the negative. Anywhere else the current is dirty (ie other devices are using voltage/current ). Also the direction the shunt goes in is also very important. Pay close attention.
You‘re reading current/voltage after the bms(the red device) this is not the power from the battery (ie it’s to the battery). The power gets used from the inverter (load) so it should be between the inverter and the battery. The current read is what you used and not what you are putting in the battery at the BMS.
Also you need to zero the the shunt. (Nothing running) . The voltage you read should be equal to the voltage at the positive and negative post.
When you reach 100% it should sync(when your batteries reach full voltage and the current has dropped). If it doesn’t, something is wrong with your tuning parameters, but if you get to the proper voltage and current drops, and the shunt doesn’t sync, you can sync it manually until you tune the parameters.
I set it manually when I put it in. When I first reached the proper voltage and the current drops for a minute, I manually synchronized the shunt. At this point I watch the shunt for a few days.
Checked the history to see if it auto synchronized And tuned the parameters until it began to see automatic Synchronizations. Obviously this is dependent on weather and charging.
It took a little while. Change parameters one at a time and document it, in the beginning . Changing more that one or two parameters at a time will not allow you to understand the affects.
Hope that helps.

 

[Short_Shot]

A wiring diagram of the system in its current state would help immensely so we can correct the issues.

 

[Randij]

The diagram is pretty clear. From your picture, I put my shunt between the black terminal connector of all the batteries and the charge controller. Ie I wired the right side of the shunt to the battery terminal of all the batteries . No other black wires leave the right side of the shunt and the terminal of all the battery. The left side of the shunt goes to my charge control. No other black wires leave the left side of the shunt and the charge controller. There is a small red wire with a fuse that goes between the green terminal and the red terminal of one battery, and not the red terminal of all the batteries. (my batteries are all in parallel and are 24v ). I did this incase something goes wrong at the all batteries terminal since the shunt only needs the power of one and the is a lot of current here. I don’t know if it matters if it connects to the red terminal. I just have not done so.
So in your picture take the shut off the bms. The top black wire goes to the black terminal where the bms is attached.
The blue wire is removed and goes to the bms wire you removed. The top black wire you removed from the shunt goes to the bms where the blue wire use to be.(ie the black wire from the fuse above the blue inverter goes to the bms where the blue wire was connected).
Totally different place . The shunt is now sensing the current/voltage at the battery.
‘Hopefully the shunt hasn’t gotten damaged the way it is installed now.
Another thought.
‘Again, my bms is in my batteries and so according to that, the problem is that the shunt is in backwards. The shunt connection is reversed.
You could try that and see . . I think this is a better choice to try first to see if the shunt is broken. Then, if the voltage appear to be off, it might be that the shunt should be on the other negative of the bms between the batteries.
‘I was wrong in my previous text. The shunt was not connected to the inverter. I checked.’ I apologize.

 

[Scph9002]

Victron smart Shunt can be both after or before bms. It doesnt matter.

Your bms is turned off. Apply a charging voltage that is 2 or more volt above battery voltage to turn it on.

There are several other ways to turn on daly bms. Search forum

 

[Randij]

Scph9002,

Victron smart Shunt can be both after or before bms. It doesnt matter.

Your bms is turned off. Apply a charging voltage that is 2 or more volt above battery voltage to turn it on.

There are several other ways to turn on daly bms. Search forum

Is the shunt not in backwards? I’m sure the shunt is in the opposite direction in my setup.
While my bms is in the batteries, that makes sense that the shunt can go either Place.

 

[100 Proof]

Scph9002,

Is the shunt not in backwards? I’m sure the shunt is in the opposite direction in my setup.
While my bms is in the batteries, that makes sense that the shunt can go either Place.

It is not in backwards. Even if it was, it would just give reversed readings. In this case, I believe Scph9002 has it right and the BMS is not turned on or is defective.

 

[Randij]

Mine is in the other way and is giving me numbers. The end with the green connection and says battery minus is attach to the batteries or battery terminal. Just saying.

 

[mikefitz]

Victron smart Shunt can be both after or before bms. It doesnt matter.

Perhaps it does, since the shunt volt drop will give incorrect BMS readings.

The Smart shunt is clearly marked which end connects to the battery.

Mike

 

[Scph9002]

Perhaps it does, since the shunt volt drop will give incorrect BMS readings.

The Smart shunt is clearly marked which end connects to the battery.
View attachment 66727
Mike

No voltage drop that matters. It is 50 mV drop at 500A. In any case the only reading it could affect if it actually had enough resistance would be battery voltage, not cell voltage. But im pretty sure most bms measure battery voltage with balance leads anyway, not the conductor leads so any resistance between bms and battery would not matter.

Actually victrons smart shunt SHOULD be between battery and bms because else it would power down and reset some settings if bms cut off power.

On a side note, i love the low resistance on victrons smart shunt. Normally cheap china meteres use shunts that is 75mV at 100A. At 80A these shunts get so hot you cant touch them. At 100A 7.5 watts of power i lost as heat through these shunts but 100A through Victrons 500A shunt only 0.5 watt is lost :D

 

[wholybee]

Perhaps it does, since the shunt volt drop will give incorrect BMS readings.

The Smart shunt is clearly marked which end connects to the battery.
View attachment 66727
Mike

Even if the voltage drop were rather significant, it would not matter. The shunt and the BMS both measure current. Current is the same everywhere in a series circuit(the shunt is series with the BMS) Changing its position changes nothing.

Voltage is measured from the balance wires, position of the shunt doesn't affect that either.

 

[Randij]

Perhaps it does, since the shunt volt drop will give incorrect BMS readings.

The Smart shunt is clearly marked which end connects to the battery.
View attachment 66727
Mike

Thanks Mike

 

[740GLE]

Still think the issue is the 2 volts across the BMS B- P- and the that the BMS worked only when B- P- is shorted out. Sounds more of a BMS issue that system design, shunt location.

 

[100 Proof]

Still think the issue is the 2 volts across the BMS B- P- and the that the BMS worked only when B- P- is shorted out. Sounds more of a BMS issue that system design, shunt location.

Agree. Sort out the BMS issue first.