I have installed the GX touch, Cerbo, and shunt to my house bank that also has the MPPT 100|30 for my 175 watt array. When there is no sun the system looks good and there is zero current draw as I don’t have anything running. However when the sun is out and I still don’t have anything running it shows a DC load of of 8 to 11 amps. It seems to increase if I am getting more solar. I did add a 3 amp load from a fan just to see what happened and it just adds the 3 amps to the pre-existing mystery load. Thoughts?
Shunt wired up wrong with the MPPT negative is connected direct to the battery rather than the load side of the shunt and is bypassing the shunt and not being measured. The DC loads tile is a calc so if the shunt is not measuring solar then the DC loads is also wrong. See links below.
Thank you for the response. I just rechecked the wiring and I have one negative lead between the battery and the shunt while everything else is appropriately on the load side of the shunt. Any other thoughts? This boat has had previous owners. I suspect that some of the wiring may have been done where they used the hull as ground. Could this explain the mystery draw?
Did you correct it though? If you didn’t then do so.
Basically nothing should be connected to the battery negative at all except the one connection from the shunt.
If there is still a draw after wiring is correct, then start isolating circuits until it stops.
1 Like
If the hull is used as a negative conductor (it absolutely should not be used as a negative conductor) then as long as the hull ground connection is made to the shunt load side not the battery then these currents should be measured.
Okay I will flesh this out further regarding the possible use of the hull as grounding. One bit of evidence worth noting.
I have two systems. A 12 volt and a 48 volt (strictly for propulsion). The problem is readily apparent on the 12v side. I’ve assured that I have both systems are wired correctly to their respective MPPTs, shunts, and devices. I’m going to need to check all the devices ground.
However, when I have the 48v systems MPPT turned on I see that there is a significant jump in the DC amps on the 12v side. I do have both shunts fairly close to each other(maybe separated by 3 inches). I’m wondering if this could be the source of the problem?
They work by measuring the volt drop over them. If you are thinking it is interference it is not likely, unless they are touching.
Again it shouldn’t be a problem if nothing is connected the battery except the connection from the shunt for SOC.
Or the mppt is connected the dc laods shunt instead of the soc shunt.
Shunts are wired properly. You can see the discrepancy looking at the app and comparing it to the GX Touch.
I am afraid that you are looking at 2 different items there. The VictronConnect app is showing the amps flowing into or out of the battery as measured by the shunt. The item you have highlighted on the GX Touch is the current flowing to the DC loads not the current to the battery. On the GX Touch solar is producing 4.2A, DC loads are 3.6A so there is 0.6A going in to the battery, close to the 0.9A on the app direct from the shunt. You can not expect a bsolute accuracy at such low currents.