Mystery switching on the 28SS?

[vlamgat]

I have just seen a close up of a 28SS Explorer power bay and noticed it has 2 red rotary cut off switches - what is the function of these? Presumably one is for battery cut off and the other? Or....

[WeQuit]

Originally Posted by vlamgat

I have just seen a close up of a 28SS Explorer power bay and noticed it has 2 red rotary cut off switches - what is the function of these? Presumably one is for battery cut off and the other? Or....

If I'm understanding the wire layout correctly, the rotary on the left isolates solar (if for some reason you want to turn off solar charge) and the one on the right disconnects batteries from all else.

- Matt

[vlamgat]

Originally Posted by WeQuit

If I'm understanding the wire layout correctly, the rotary on the left isolates solar (if for some reason you want to turn off solar charge) and the one on the right disconnects batteries from all else.

- Matt

That's interesting. So its possible to leave the solar power ON but the batteries OFF but not disconnected from the Solar Controller?

Brian, if you see this, the 28SS 12V schematic does not show 2 switches nor does it distinguish between the wiring for the battery charge regulation, the generator, the chassis or the Solar Controller. Is there another schematic that cover this aspect for the 28SS in particular? There is a 30 Chassis below floor schematic but it does not show the battery or the switches in diagram.

[WeQuit]

I did an experiment and got a slightly different result than I was expecting:

Monitoring the Victron from the app while in the electrical bay, no shore power, generator off, inverter off, both switches on. We were net charging the batteries by call it 5 amps

Left off, right on: net current across the Victron shunt went from +5 to -4. Confirms that one did what I thought it would

Left on, right off: net current went to +9. That was a surprise. I apparently need to learn a bit more about cutoffs because it seems like the right switch is still passing solar through from the left switch even in the off position (only +12V solar output I see comes out of each controller and both tie into the left switch. Only output from that switch goes to right switch). I figured right switch off would not allow that current to pass through, but perhaps there is a passthrough terminal I didn't know about (there are 3 sides of the right switch connected... so that may be what that does).

Net result seems to be that you can disconnect house bank from all loads while keeping solar charge connected to top off charge.

- Matt

[bclemens]

I would have to confirm, but this is likely just a disconnect that I asked for solar. It was likely not on early electrical drawings as we did not have it...but I had asked for a disconnect a while back just in case someone needed to work on something. While not a big output, the last thing we want is solar charge coming in while we are working on things.

[toshu]

Originally Posted by WeQuit

I did an experiment and got a slightly different result than I was expecting:

Monitoring the Victron from the app while in the electrical bay, no shore power, generator off, inverter off, both switches on. We were net charging the batteries by call it 5 amps

Left off, right on: net current across the Victron shunt went from +5 to -4. Confirms that one did what I thought it would

Left on, right off: net current went to +9. That was a surprise. I apparently need to learn a bit more about cutoffs because it seems like the right switch is still passing solar through from the left switch even in the off position (only +12V solar output I see comes out of each controller and both tie into the left switch. Only output from that switch goes to right switch). I figured right switch off would not allow that current to pass through, but perhaps there is a passthrough terminal I didn't know about (there are 3 sides of the right switch connected... so that may be what that does).

Net result seems to be that you can disconnect house bank from all loads while keeping solar charge connected to top off charge.

- Matt

So if you got in trouble and needed to charge your house batteries fast, you could turn off the Right switch, isolating the batteries from any draw, and the panels will charge them up quicker via the Solar on, Left switch

[WeQuit]

Originally Posted by toshu

So if you got in trouble and needed to charge your house batteries fast, you could turn off the Right switch, isolating the batteries from any draw, and the panels will charge them up quicker via the Solar on, Left switch

It certainly seems that way to me. I also realized how you get across the right switch with the hot solar lead when right switch is off. That +12V coming out of the left switch must just be stacked on the battery side terminal of the right switch instead of on an independent terminal block behind it... duh. My density amazes me sometimes.

Either way, pending confirmation from somebody else doing their own test watching the amp flows on the Victron as you switch the switches, I think left switch kills solar, right switch kills loads. Solar passes through the load disconnect switch (right switch). So solar on, loads off leads to full solar output going to charge.

I like the setup a lot Brian. The second switch is the way it should be. It just took some staring at wires to figure it out.

- Matt

[vlamgat]

Thanks for the insights everyone. Really helpful and the logic makes such sense. I have been wondering (and had asked) whether the battery cut of removed the effectiveness of a Shore connection. From this string it would appear that the right switch removes the loads and retains the solar charge.

Does the same apply for Shore power?