Victron MultiPlus II Inverter/Charger

[Randyretired]

2 hours ago, Zulu said:

I'll go with the flow in this one. I think every schematic I've seen, including from Victron, shows the Class T fuse before the disconnect switch.

Also, after talking with a guy who used to do marine inverter installs, I updated my schematic and added an AC disconnect right before the inverter along with other changes people suggested.

Thanks folks!

I fused the lead to existing 12v loads.  I also fused at the bus bar to protect all of the wires on it instead of near the connected circuits. Specifically the charge controller.  If the wires are short and safe it probably doesn't matter.

Edited January 27, 2022 by Randyretired

[Zulu]

1 hour ago, Randyretired said:

I also fused at the bus bar to protect all of the wires on it instead of near the connected circuits. Specifically the charge controller. 

I've been thinking about doing the same after seeing some of Chad's schematics like this one below that I believe uses a Victron Lynx Distributor instead of conventional bus bars:

[Chad Heiser]

When I really started getting into installing Victron products, I migrated from the Class T fuse for the batteries/inverter and individual resettable breakers for each branch circuit to the Lynx distributor.  It usually simplifies the wiring overall and gives a single place to look for fusing if something stops working.  It was also often cheaper in the long run.  I do still add additional circuit protection for the solar with a Midnite solar baby box and some MNEPV breakers though.

[Zulu]

Victron MultiPlus II AC-IN fusing/circuit breaker

I've started wiring my RV for its eventual solar upgrade. As part of this process, I have to disconnect the AC panel input from the Transfer switch, and then run this Transfer switch output about 12 feet to my Victron MultiPlus II inverter. (They'll also be a similar AC run back into the AC panel.)

I was going to install a AC disconnect switch on the Transfer switch output going into the Victron inverter, but found this in the Victron MultiPlus II manual for the inverter's AC-In:

The AC input must be protected by a fuse or magnetic circuit breaker rated at 50A or less, and cable cross-section must be sized accordingly. (BOLD text by Victron)

This seems like a much better solution than an AC disconnect switch.

[GlennWest]

Does that unit use the push in connectors? Seen that on some newer units and seen failures also. 

[franco-bolli]

I stumbled into this a while ago for a different project, maybe it will help with wire sizing.

NOTE: this is for DC currents.  the source is Engineering toolbox

[Zulu]

1 hour ago, GlennWest said:

Does that unit use the push in connectors? Seen that on some newer units and seen failures also. 

Yep. Were the failures you saw on Victrons?

[Chad Heiser]

Assuming your trailer is not hard wired to an electrical source, your AC in on the inverter is protected by the pedestal you plug the trailer into (and it’s breaker) and (since you said transfer switch) by the circuit breaker built into the generator (if you have an onboard generator).  There is no need to add an additional breaker.  There is no need for an AC shutoff switch either.  If you want to add one it won’t hurt, but there is no need for one.  I have seen some people add a bypass switch so the inverter can be cut out of the system in case it fails.  Personally for the very unlikely event of a complete inverter failure, I would simply remove the AC in and AC out wiring from the inverter and wire nut those lines together temporarily until the inverter was repaired.

[Chad Heiser]

2 hours ago, Zulu said:

Yep. Were the failures you saw on Victrons?

There have been some failures with the Multiplus II push in AC connections posted on line.  Every one I have seen can be explained by improper installation by the DIY installer.  Follow the instructions and install the connections properly and you will have no issues.

[Zulu]

1 hour ago, Chad Heiser said:

There is no need to add an additional breaker.  There is no need for an AC shutoff switch either.  If you want to add one it won’t hurt, but there is no need for one.  I have seen some people add a bypass switch so the inverter can be cut out of the system in case it fails.  Personally for the very unlikely event of a complete inverter failure, I would simply remove the AC in and AC out wiring from the inverter and wire nut those lines together temporarily until the inverter was repaired.

I want a quick way to shut off the AC In to the inverter.

I’m still going with dual 50A breakers instead of a simple AC cut off as I’ve seen too many suspect pedestal breakers.

 

[Zulu]

1 hour ago, Chad Heiser said:

There have been some failures with the Multiplus II push in AC connections posted on line.  Every one I have seen can be explained by improper installation by the DIY installer.  Follow the instructions and install the connections properly and you will have no issues.

I’ve started using ferrules which go a long way to making wiring more secure.

[GlennWest]

I felt this needed bring up. Yes ferrules is the way to go. Failures I saw are melted connections. I am not a fan of push in connections. Wished Victron hadn't went that way. https://m.facebook.com/groups/2589581644599315/permalink/3831170990440368/

Edited March 7, 2022 by GlennWest

[franco-bolli]

here is a source I use at work for Ferrules:
www.ferrulesdirect.com

That site has a huge selection of many types of terminal ends, ferrules and zip ties.

Make sure you use the correct tool to crimp them on, or a poor crimp could result in a poor connection that heats up under high current and melts insulation. Heat is wasted energy and depending on what is near by, could cause a fire.

[GlennWest]

They on Amazon also. I got a lot with assortment of ferreules. 

[GlennWest]

6 hours ago, Zulu said:

I’ve started using ferrules which go a long way to making wiring more secure.

What crimper you use. Those ribs aren't on mine. 

[folivier]

This is the one I use, showing not available on amazon but may be elsewhere. And there are other brands also.

 

https://www.amazon.com/gp/product/B07212XQTV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[Zulu]

4 hours ago, GlennWest said:

What crimper you use. Those ribs aren't on mine. 

Hex crimper

[GlennWest]

Have to get one of them. Use my hydraulic for #4 up. 

[Chad Heiser]

14 hours ago, Zulu said:

I want a quick way to shut off the AC In to the inverter.

I’m still going with dual 50A breakers instead of a simple AC cut off as I’ve seen too many suspect pedestal breakers.

 

Nothing wrong with that.  I do it for all my dual inverter installations, but it is more because I need to split the four wire (L1, L2, N, G) feed into a six wire (L1, N, G and L2, N,G) feed and back.  I use small (70 amp) load centers with 50 amp double pole breakers to make the split and then re-combine back to four wire.  One box/breaker goes on the AC input side of the inverters and the other goes on the AC output side of the inverters.  For your installation you would just need one on the input side to do what you want.

[Chad Heiser]

14 hours ago, Zulu said:

I’ve started using ferrules which go a long way to making wiring more secure.

I also recently started using ferrules.  As a matter of fact I just got a shipment of 6 awg ferrules from ferrulesdirect.com today.  They help make it easier to get the stranded wire into the connections and should also make a better connection in the inverter.

[folivier]

And ferrules also provide stress relief if there is any vibration or movement in the wires.  I used them for about 20 years when I was working.

[Elmo1706]

I bought a solar package the inlcudes a new Victron MultiPlus-II inverter for my 2009 Tiffin Phaeton 36QSH. The old Xantrex RV2012GS had two 30-amp (one hot wire) conductors as inputs and two 30-amp conductors on the output side. The Victron expects one 50-amp (two hot wires) input and output. Can I combine the 30-amp conductors by joing the two neutrals together? Some people say that combining neutrals will cause the GFCI circuits to trip. My solar dealer was clueless and I can't contact Victron directly.

[GlennWest]

3 hours ago, Elmo1706 said:

I bought a solar package the inlcudes a new Victron MultiPlus-II inverter for my 2009 Tiffin Phaeton 36QSH. The old Xantrex RV2012GS had two 30-amp (one hot wire) conductors as inputs and two 30-amp conductors on the output side. The Victron expects one 50-amp (two hot wires) input and output. Can I combine the 30-amp conductors by joing the two neutrals together? Some people say that combining neutrals will cause the GFCI circuits to trip. My solar dealer was clueless and I can't contact Victron directly.

So you have a 30 amp rig? If so just wire in L1, Neutral and ground. Leave L2 disconnected. You will just always have 30 amp. 

Edited July 14, 2022 by GlennWest