Victron Multiplus II 3100 DIY install

The Issue:
I purchased a Victron Multiplus II inverter thinking I would just install it using the Inverter Prep in the forward bay but after watching numerous videos on the topic realized, that in order to run the AC (and to have true Hybrid functioning) then both of the 30 amp inputs in the Main Breaker box need to be wired into the Victron and, I would think, the Inverter Prep is wired to just one (one of the videos stated that you can’t run your AC off of an inverter installed using the prepared set up). The Inverter Install Manual is no help and I can’t find anything about it on the Brinkley website. It occurred to me that one of the connections could be made using the Inverter Prep and the other using the Generator Prep wiring. That way I’d avoid having to run new wires back to the Breaker box.

The Question: Have any of you installed the Victron (or other inverter) and were able to run your AC? If so did you have to run a second bundle of wires?

I have Victron installed.
I didn’t use any of the Factory installed wiring. And I wouldn’t really recommend you do either. The only wire you could even use would be the gen prep. But its not really long enough. Unless you use a junction box. So what I did was I installed a Power Watchdog also. I removed the Power from 50Amp plug that ran to the Panel and pulled it back to where the Watchdog was. Then I ran a new cable from the watchdog output to the front compartment into the Multiplus input. Ran a new wire from Multiplus output back to the panel.
All this said it was not the easiest installation. I can show you how I ran the cables. I opted to run them thru the camp side LP tank compartment. Because I mounted the Multiplus on the side of the forward compartment so I would lose allot of room and I have 4 Lithium batteries.
You need to consider the batteries to. For best results Lithium is the only way to go.

The chill cube only pulls about 900 watts and the rear AC pulls about 1200
So I have run both of them at the same time on my Multiplus II
I also opted to remove the battery box and covered it with some Galvenized steel Sheet. I used Flex Seal to paint the bottom side so no water can get in the cracks. I this photo i had not yet installed the batteries. Im using 4 280AH Lifepo4 batteries.

1 Like

I can upload a video of how i ran the wires if you like. I didnt want to see them so i tried to keep them and high thru the compartment as possible.

Hi Tony. Great response! Just the info I was hoping for. Thank you!
Yes I’d love to see more of your install process.

I have LiFe PO 280ah x 3 (SOK brand). (My victron arrives tomorrow)

So you only used one of the 2 AC outputs on the MP II?

Will you still get the hybrid charger and power assist features with your setup?

Z 3100 #2309

That’s is correct the multiplus will power assist on output 1 and you don’t need to use output 2.

The multiplus will charge the batteries and you will need to disable the power converter ( turn off the breaker) when plugged into shore power the inverter will supply the system with power and charge both.

If you draw more power than the shore can deliver.

Say you’re connected to 15 amp outlet in your garage.

Power assist will supply power to any heavy loads.

Did you order a usb dongle to program the inverter?

You’ll need to set it for lithium and enable power assist.

I am going to be working this weekend off dual Victron Multiplus II 3000 48v install. I will make sure to post pictures once I get the install done for the 3610. I also got the whole rig 50a soft starter that I will be putting after the Victron’s to power all the loads.

A friendly suggestion, it is best to talk about batteries in kWh and not Ah, as that is dependent on voltage. Yes stock is 12v but most people will upgrade to 24v.

I went direct to 48v but I knew the limitations of that with Victron equipment as in no optimal DC-DC converter and the Multiplus II 2 x 120’s are better for many use cases. I wanted the UPS function more than anything and that feature has saved me in the past many times, especially with dogs in the coach when I am way.

Interesting finding that these coaches really can just be 30a units. I ran three AC’s on a 80+ day and pull just over 1300 watts on both legs. The low profile Furrion installation may suck but they are really efficient. That ~2600-2800 watts was with everything running which was impressive.

I did some extensive power utilization measurements this past week with the AC running and found that for 10 hours overnight (with the rig already cooled) I only used 4.8 kWh with the Furrion Chill Cube and the two low profiles all running.

Thank you Patrick! " Interesting finding that these coaches really can just be 30a units. "
So can I just use the 2 (supplied 30 amp lines that run to breakers 9 an 10 on the 3100 panel) lines that are preinstalled with the “Inverter Prep”?? One would be AC out line 1 and the other AC out line 2? What would you think about using the Cable in the Generator Prep junction box to run the AC in to the Multiplus (trying to avoid having to run cable half the 3100 length)?

No I haven’t order the USB dongle. Will do ASAP

I think that was Brinkley’s intention according to what the regional rep told me last year. I just wanted to see the true utilization and was fairly surprised.

My intention is to use the generator prep wire as the feed. I already took apart the shore connector and put in a Power Watchdog with a few feet of 6 awg. The feed will come out of the Power Watchdog to a net new 6 awg wire that I will run parallel to the existing generator feed cable. My understanding is all I need to do to access and follow he factory wiring is drop the front screws on the coroplast. That will have enough length to feed both inverters. I have to join the neutral and ground because I will have two Victron’s but probably will tap them with a 3 way and run independent ground and neutral to each Victron.

From the Victron output I will go to the generator prep with a tap and then remove the generator prep box in the front compartment and mount the ActiveStart 50a hardware. Then I will rejoin the factory wiring to the panel to the ActiveStart

[Shore Inlet] → [Power Watchdog] → [Victron Multiplus II 3000 48v] → [ActiveStart] → [Panel]

The inverter prep is only a single leg from what I have seen so I am running new wire.

The Multiplus and Multiplus II have two outputs but when you loose power the second feed will not operate at all. You can not use it to invert with, so it is only active for shore power pass though. These are available in a 12v, 24v, or 48v (MII only)

The Multiplus II 2x120 has a feature that when a loss of shore power it will automatically bridge the second output. That means that in split phase service you will have power on both sides of your panel. Just note that the second output has a delay and will be interrupted but the primary leg will still have UPS. You can stack them and get up to 6000VA.This is probably the easiest model for most people is you are ok with power being interrupted on one leg, available in 12v and 24v.

The charger output is based on the AC output the unit is working and what you set your maximum shore to. So if you have 15a as the max shore power and are using 10a in the coach, you will roughly charge 12v at 50a. I should note that Victron max shore power setting is not the maximum all the time, it will run lower than that amount. It takes into account a few variables to make sure you don’t overload the shore power. It is not uncommon to set them to 20a and only be able to pull say 16a.

I think I got it now. You brought the 240 v (120 x 2) straight from shore power (with Watchdog) to the Multiplus II and are running the same power (either by pass through or inverter) out to the breaker panel (slots 5 and 6). You advise against using the supplied cables because they go to the 30 amp breakers and are too small to move over to the 50 amp breakers (5 and 6 on the panel)?

I guess technically if your in a Invert only On battery situation you could consider that a 30 amp like situation since the multipus Ties L1 and L2 togeter in that situation. It is correct there is a 30 or so Milisecond delay on L2 when power is lost to tie the legs together. Power must be disconnected from L2 and tied to L1 and that switching takes miliseconds but still there is a loss of power on L2. IN shore 50 amp its 50Amp 50 on L1 and 50 on L2 in a 30 amp situation once again L1 and L2 are tied together. This is all done Inside the inverter automatically. Its compicated but simple to.

as far a AH VS KWH 6 in one hand half a dozen in the other i would say…but most of the batteries are still rated by AH. but you use any Calculation you wish. Its all ohms law either way.

Oh and he is right 24 or 48 volts is the way to go. but i already had my Multiplus from my last coach. but if i were doing a new install. I would definatly go at least 24 volts. Maybe not 48. But definaly 24. Its just so much more efficiant and you dont need those huge cables.

Here is the first day of the Victron Multiplus II 48v install. I have only cut but didn’t terminate any of the wiring.

The one thing that I will say is just drop the coroplast and on the driver side follow the factory 6awg wire. I really thought running a second circuit would be the hardest part but it took me less then 30 minutes. I just need to get some seal tight to cover the wires passing through the frame. It switches a few feet into the chassis to convoluted tubing. I zip tied mine to the exiting factory run and cross members.

More to come as I work on the project.

Do you even need that shunt with those EG4’s. Dont they have Victron Comms. If i could do it over i would have dropped my Shunt and used the EPOCH batties and Victron comms for Battery Management. You get a better state of charge since its comming from the battery BMS and its not a calculation from the Victron SHUNT. Just my $.02

That photo is pretty impressive. The two inverters look really good. Not sure how you getting any cables in your Linx though with it mounted so close to the inverter. But 48 volt you wont need huge cables.

And if you not cussing while your trying to install those 6 AWG cables into the inverter. There not in all the way. I hate those connections!!

On another note, I called Brinkley and asked them if they could give me any info like wiring schematics on a 3100. Told him i was going lithium and setting it up for full boon docking. He said they don’t have any schematics and don’t get involved with third party modifications. Thanks Brinkley. We suppose to just guess where are the wires go? What a disappointment. I guess we just lifting panels and disassembling everything and figure it out the hard way. He could not even tell me what air conditioners were installed, told me to go to Furrion website and I would see it. That right there is lousy tech support and poor records keeping. Not impressed.

I hear ya. The B website is pretty weak once you get past the very outer edge of the weeds . . .
The Victron Website OTOH is great. Also there are several good YouTube vids of 3100 Victron installs.

In the process of running the AC cables to the forward compartment (I’m splicing onto the 50A run from the plug) I see that the Brinkley supplied 50 A line is 10/4 (!). I found that quite surprising, considering how every wiring scheme I’ve looked at calls for 6/4 cables. I’m going to use the 6/4 I already bought.

Never mind. I just realized that it’s only the ground wire that is 10 AWG.