On my boat I have a single negative wire that brings back the starter and house battery alternator negatives from the engine (negative earthed alternators). This goes to one side of a shunt with a cable to the starter battery negative. The other side of the shunt connects to the house battery negative. I am lucky that I could put it in the negative wire, many cases can not do this and it needs to go in the positive wire. I prefer negative as the signal cables do not need fusing.
Attached schematic which I have removed the clutter from so you can see the key alternator wiring
Hi
My shunt is placed more or less on the same spot as yours, according to the drawing.
Physically its visavi the Distributor.
The picture was taken before I had the third 24V 200Ah battery installed, so now the housebank is 600A. The two grey ones are 12V AGM in series acting as an emergency 24V bank, and to the far lright you find the 12V starter battery. This is on a yacht, as you probably guessed.
I have the same issue as you, with the shunt mounted backwards. This just happened by coincidence, and since the easies way to change it was by programming the Wakspeed, I did that in stead of turning the shunt physically.
Henrik
It just sees the domestic one because the negative wire to the starter battery comes off the same side as the common line from the engine so only the house battery current goes through the shunt.
In a single alternator setup with a Lynx Shunt (Ve Can) is it possible to separate the charging output display into Solar and Alternator by adding a shunt to the starter battery? If this is configured as Alternator will the Cerbo subtract that from the charge going into the house bank through the Lynx Shunt? Alternator output goes to an Argofet and then splits to starter battery and house bank (ultimately to bow-thruster battery too once there is a separate one installed with its own shunt).
The internal calcs in Venus consider other DC current/power measurements from a SmartShunt set as DC Energy Meter as relating to the house batteries. If you put a shunt on the starter or bow thruster batteries and set this as an energy meter and call it alternator then the system will consider that these are charging the house batteries. You can put a shunt on the batteries as a battery monitor to see what is going in from the alternator. You could then do some work in Node-Red to calculate the load from the alternator to the house batteries.
The only way to get a figure for the alternator or alternator to house battery is to try and sort out the negative wiring like in my sketch. A version of the SmartShunt that worked in the positive cable would be the solution. I think there are posts on here or the old community about DIY positive SmartShunt look a likes.
OK thanks - I’ll think about that - I see the charge from the alternator in VRM from the Lynx. It seems like a lot of wiring complications to get an Alternator box in Remote Console ;-). Using shunts as battery monitors for the two “technical” batteries seems the way to go.
@pwfarnell I dug out the wiring diagram and the negative cables are electrically the same as yours … the difference is that the Lynx shunt can’t be told it is an alternator (the only non-solar DC source I have) so maybe the answer is to remove the Lynx shunt and replace it with a Smartshunt …
You could pop in a feature request but my guess is that it is an older design like the BMV-702 and is too limited to have a significant firmware update to act as a DC energy meter.
