Do I need a disconnect switch for my inverter?

[corn18]

For the life of me I can't remember why I put a giant on off switch on the 12v input to my Victron MPII. I'm sure I had a good reason at the time. Thought maybe someone could help me with a good reason to have it.

 

[justinm001]

Absolutely zero reason to have it as you can turn the inverter on/off/charge only/inverter only. Even then you can flip the main on/off and pull the MP fuse in the lynx.

I guess to let you work on the inverter without turning off the solar? But you can just turn off the mppts remotely.

Since your batteries don't have a switch then the on/off there is good.

 

[corn18]

The solar panel breakers are right there in that same compartment so I can completely isolate the inverter from power if I need to work on it. Maybe I installed it when I was having issues with my SOK BMSs going into protect all the time. That issue has been solved with the BattleBorn current limiter so I don't think I need that inverter disconnect switch anymore. Just trying to simplify things.

I also don't need the multi control panel so might just remove that, too.

 

[justinm001]

You should adjust your battery wiring as well. If you're running cables to them both then they should be the same exact size. This way one battery isn't closer than the other. Typically with 2 batteries you just run the positive from one and the negative from the other then wire both batteries together. With yours you'd need to stack the lugs on the battery terminals (bigger batteries usually have 2 terminals for each).

I'm digging those colored wires BTW

 

[time2roll]

No switches for me on the main power cables. I plan to turn systems off and lift a cable if service is needed. Could be years before anything is disconnected.

 

[Dave in AZ]

The solar panel breakers are right there in that same compartment so I can completely isolate the inverter from power if I need to work on it. Maybe I installed it when I was having issues with my SOK BMSs going into protect all the time. That issue has been solved with the BattleBorn current limiter so I don't think I need that inverter disconnect switch anymore. Just trying to simplify things.

I also don't need the multi control panel so might just remove that, too.

View attachment 205098

Wow this and the diagram match up pretty well, and both look good!

 

[corn18]

You should adjust your battery wiring as well. If you're running cables to them both then they should be the same exact size. This way one battery isn't closer than the other. Typically with 2 batteries you just run the positive from one and the negative from the other then wire both batteries together. With yours you'd need to stack the lugs on the battery terminals (bigger batteries usually have 2 terminals for each).

I'm digging those colored wires BTW

The positive wires are the same exact size. The negative cables are within 3/4". Not gonna do any weird stacking to get it "exact".



I had them criss cross applesauce and folks here convinced me that was the wrong way.

 

[SeaGal]

I'm digging those colored wires BTW

Mmm... Red Green Blue - looks like they should be connected to a giant video display

 

[corn18]

Mmm... Red Green Blue - looks like they should be connected to a giant video display

The red and blue ones on the far left are the low point drains for the freshwater system.

 

[justinm001]

The positive wires are the same exact size. The negative cables are within 3/4". Not gonna do any weird stacking to get it "exact".

View attachment 205185

I had them criss cross applesauce and folks here convinced me that was the wrong way.

View attachment 205186

Gotcha. They look a lot different in the pic. The criss cross makes more sense because regardless you're still limited to 4/0 wire amps as they combine at the fuse. But I don't think it really matters. I'd rather the whole system be equal and risk voltage drop (that's recorded on the shunt) over batteries not being perfect and having different cycle counts months/years laters.

 

[OffGridInTheCity]

I guess to let you work on the inverter without turning off the solar?

I do this via breakers, let's me protect the wire from battery -> inverter as well.

But you can just turn off the mppts remotely.

Have these breakers as well, but it's nice to have specific inverter breakers to avoid loosing PV -> battery charging while working on the inverter

 

[justinm001]

I do this via breakers, let's me protect the wire from battery -> inverter as well.


Have these breakers as well, but it's nice to have specific inverter breakers to avoid loosing PV -> battery charging while working on the inverter

You really shouldnt need to be working on the inverter or anything once setup though. And if you're having issues I'd rather have everything off completely to troubleshoot.

Although 12v I'm not really worried about turning things off. 48v is another story

 

[OffGridInTheCity]

You really shouldnt need to be working on the inverter or anything once setup though.

If only it were so.... I have a pair of heavy (175lb) inverters and after 5 years one of them failed - had to go thru hoops to replace / repair - and was nice to have breakers to shut off the battery while working on things.

 

[justinm001]

If only it were so.... I have a pair of heavy (175lb) inverters and after 5 years one of them failed - had to go thru hoops to replace / repair - and was nice to have breakers to shut off the battery while working on things.
View attachment 205216

Yeah a battery disconnect is needed but we're talking about vehicle systems here and a battery disconnect plus an inverter disconnect is just redundant.

Also in a vehicle inches matter and we don't have walls with tons of space. OPs photos are pretty typical of a bay.

 

[OffGridInTheCity]

Yeah a battery disconnect is needed but we're talking about vehicle systems here and a battery disconnect plus an inverter disconnect is just redundant.

Also in a vehicle inches matter and we don't have walls with tons of space. OPs photos are pretty typical of a bay.

Agree that space can be tight - for example, I also have a trailer ->camper w/inverter and breakers (battery -> inverter, and other) which were helpful in recent work adding a 2nd battery.

Good discussion and I hope it helps the OP

 

[corn18]

It does help. I will be removing the switch.

 

[corn18]

The switch has been removed.