stefprez avatar image
stefprez asked

Which Victron components should be connected directly to the battery?

Hello! I have a 12V system in my RV with two 12V LiFePO4 batteries wired in parallel, a SmartShunt operating in Battery Monitor mode, a Smart Solar MPPT 150/45 solar charge controller, and a Cerbo GX with GX Touch 50 connecting everything. I also have a battery disconnect switch that currently disconnects all of the non-Victron loads in my system. I have some questions about best practices with respect to wiring each of these components and would greatly appreciate your help!


I have my SmartShunt wired into the negative side of my circuit, directly between the negative terminal on my battery bank and all other loads. I have the Vbatt+ terminal wired directly to the positive terminal of my battery bank using the optional battery temperature sensor (with black wire connected to the aux terminal and configured correctly). I don't think I have any questions or concerns here. The manual is very clear about how to wire everything. This results in the SmartShunt being "always on" regardless of the battery disconnect switch position.


I have my MPPT charge controller wired to the battery bank's positive terminal directly (always connected, even if battery disconnect switch is turned to off) currently unfused, but in reading the manual more closely, it looks like I should add a 50A fuse to this connection. The negative connection connects to the load side of my SmartShunt. Regardless of fuse, is it recommended to have the MPPT connected directly to the battery, as I do now, or should I put it on the "load" side of the battery disconnect switch, such that if that switch was turned off, no power would be able to go into the batteries from the MPPT (assuming solar power was supplied)? Or is it a personal preference? I see pros and cons either way, and don't think it would make a huge difference for me in either case, but would love to hear your thoughts.

Cerbo GX (main question)

I currently have my Cerbo GX powered directly from the battery bank's positive terminal with the supplied fused cable such that if I turn off the battery disconnect switch, the Cerbo GX remains powered up. (Negative side goes to load side of SmartShunt.) This has the downside that turning off my battery disconnect switch does not get rid of the power draw on the battery of the Cerbo GX (which appears to be ~3-5W). This has the upside of always keeping the Cerbo GX on and monitoring. My main question is: Is it problematic to turn off the Cerbo GX when I turn off the rest of my loads in my RV? This is usually when it is in storage and not in active use. While the idea of having the tracking of temperature sensor data and battery voltage is nice during storage, it doesn't seem critical to me. I just can't find anything within the manual that specifies whether it is better to keep the Cerbo GX "always on" or if it's okay to disconnect when not in use. Compared to say, the SmartShunt, which is "always on" but has such a small power draw that it seems like a non-issue. Any guidance on this would be greatly appreciated! (I unfortunately just accidentally drained down my battery, I believe in part due to the draw of the Cerbo GX, which is why I am wondering if I should remove the parasitic drain.)

Thanks kindly for your reading and assistance!

cerbo gxbatterywiring
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
klim8skeptic avatar image
klim8skeptic answered ·

@stefprez I am wondering if I should remove the parasitic drain.

3-5w an hour for the Cerbo accumulates pretty quickly. That's between 6-10Ah a day. Just for monitoring.

If you are not going to be using your system for a while, have all loads, chargers and Cerbo on the system side of the battery disconnect.

The SmartShunt can stay connected to the battery given its low 1mA current draw. (that is less than 1Ah per month.)

1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

stefprez avatar image stefprez commented ·
Thank you for your response @klim8skeptic ! I think I will move over the MPPT and Cerbo to the load side of the disconnect switch as suggested to avoid the parasitic drain.
0 Likes 0 ·