Victron Multiplus-II 2 X 120v Hum/Fan

[truckasaurus]

I used the AC2 output on my Multi via a fused box to power the air conditioner. I wanted to be able to leave the AC or heat running whilst on shore power and go away with the knowledge that if the shore power was interrupted it wouldn't deplete my battery.

[jnm30327]

"What continues to cause a problem for us is when the shore power blips for a brief moment. "

Good point. I had not thought of that.

[goldenchase]

Originally Posted by richard5933

What continues to cause a problem for us is when the shore power blips for a brief moment. The Victron senses the loss of shore power instantly and switches to running everything from the inverter to provide seamless power. When the power has a momentary outage like this (which happens from time to time, especially in more remote or older campgrounds) it takes a few minutes for the Victron to reconnect to it. During that few minutes, if there is a heavy load running like an a/c it will cause the Victron to shut down due to the overload situation or a low-voltage error.

Just my experience based on our install, but I suspect we're not the only ones.

Any idea what parameter is being exceeded when the Multiplus-II falls back to inverting after a momentary outage of shore power? Installing a second panel for surplus loads is not a big deal if it avoids the problem.

[richard5933]

Originally Posted by goldenchase

Any idea what parameter is being exceeded when the Multiplus-II falls back to inverting after a momentary outage of shore power? Installing a second panel for surplus loads is not a big deal if it avoids the problem.

In my case two things happen...

First is that even with four L16 batteries my voltage drops quickly with heavy loads applied through the inverter. So for instance, if the electric element of the water heater is firing when shore power is lost I'm good for about two or three minutes before the battery voltage drops to the cutoff point. After a few minutes at rest the voltage recovers, the inverter starts again, and then it's lather rinse repeat.

The other issue which happens even faster is if more AC loads are being pulled than the inverter is capable of supplying. For example, if both an a/c unit and electric water heater are running when shore power blinks. That results in an instant overload error causing the Victron to shut down fully. The only way back from this is a hard reset by moving the toggle switch to 'off'.

[goldenchase]

Originally Posted by richard5933

In my case two things happen...

First is that even with four L16 batteries my voltage drops quickly with heavy loads applied through the inverter. .

So is it possible the issue is with the L16 AGM batteries and not the MultiPlus-II. Do you think the same thing would happen with lithium batteries?

[richard5933]

Originally Posted by goldenchase

So is it possible the issue is with the L16 AGM batteries and not the MultiPlus-II. Do you think the same thing would happen with lithium batteries?

I thought about that. Certainly the L16 batteries don't have the same capabilities as the equivalent sized lithium batteries due to the voltage drop off of them. But, if 780Ah of L16 can't sustain more than a brief few minutes of heavy draw from a 1500w water heater element how many lithium batteries will be necessary to accomplish it?

Even if you lick the problem with the battery capacity, there is still the issue of simply overloading the inverter if shore power blinks while heavy loads are running. Aside from the two a/c units which might be running there is the water heater and possibly other appliances.

Using the second switched output for these heavy loads means that the Victron could self recover once shore power is restored.

[goldenchase]

Originally Posted by richard5933

I thought about that. Certainly the L16 batteries don't have the same capabilities as the equivalent sized lithium batteries due to the voltage drop off of them. But, if 780Ah of L16 can't sustain more than a brief few minutes of heavy draw from a 1500w water heater element how many lithium batteries will be necessary to accomplish it?

Even if you lick the problem with the battery capacity, there is still the issue of simply overloading the inverter if shore power blinks while heavy loads are running. Aside from the two a/c units which might be running there is the water heater and possibly other appliances.

Using the second switched output for these heavy loads means that the Victron could self recover once shore power is restored.

Just checked the Multiplus-II specifications. Looks like the inverter is only rated at 2,400 watts continuous depending on temperature. So this may be the answer. If load is over 2,400 watts with power interruption Multiplus will likely shutdown. Need to use secondary output.

[AS_Gary]

Hey MtBackPacker - is this what you were referring to? Are you saying that I can use the aluminum there as a ground?

Under the fridge where the cable race way crosses the trailer is you have access to the frame rail. It’s right there in the open and makes a perfect place for a chassis ground without drilling the floor or messing with the belly pan.

[mtbackpacker]

No… it’s not the aluminum race way channel where the wiring crosses…. Look near by for where the plumbing crosses instead. It should be a black painted steel piece facing you across the hole as you look under there.

[AS_Gary]

Thanks I found where to ground!

Next question - since the Multiplus II charges the batteries I don't need the Converter to do that task.

Looking at the attached schematic for the DC for the Converter to the Relay to the Positive Buss Bar to the Batteries.

Which connection do I disconnect so 1) the old converter does not charge the batteries and 2) keeps all other components that need power with power?

I am thinking just the 6 GA Red wire from the Converter to the Relay.

Thoughts?

Thanks!

[goldenchase]

Originally Posted by AS_Gary

Thanks I found where to ground!

Next question - since the Multiplus II charges the batteries I don't need the Converter to do that task.

Looking at the attached schematic for the DC for the Converter to the Relay to the Positive Buss Bar to the Batteries.

Which connection do I disconnect so 1) the old converter does not charge the batteries and 2) keeps all other components that need power with power?

I am thinking just the 6 GA Red wire from the Converter to the Relay.

Thoughts?

Thanks!

Once the Multiplus is serving the DC bus you want to remove the old converter. One bonus from this is that you have one new unused circuit breaker on the 110 side of the panel.

[jnm30327]

I plan on using a Victron Lynx Distribution for DC distribution.

One branch from the Lynx will go to a fuse block. One connection from the fuse block will go to the existing DC distribution box. I will be using the Multiplus II inverter so I will remove or disconnect the current inverter from the DC distribution box. Also I will disconnect current converter.

Without the inverter and converter, what is the proper fuse size for feeding the DC distribution box? The only thing I can think of that will be fed is the DC fuse panel in the middle of the trailer. All that is just lights and fans or am I forgetting something?

Would 30 amp fuse be enough? Too much?

Using Victron battery monitor, I don't ever recall seeing more than 10 amps unless inverter was running.

[goldenchase]

Originally Posted by jnm30327

Would 30 amp fuse be enough? Too much?

Using Victron battery monitor, I don't ever recall seeing more than 10 amps unless inverter was running.

AS used 50 amp Bussman thermal breakers in the 12 volt box located at the bottom the rats nest on the circuit so I used 50 amp CB. See this post.

[AS_Gary]

What I am doing is moving the battery bank from the front of the trailer to under the seats next to the fridge (street side see pic) in attached link, don't know how to imbed pics yet).

The batteries fit nicely and running 2/0 wires Batteries  400 amp T-fuse  On/Off Switch  BusBar (for pos and neg)  Fuse  Multiplus

Multiplus II into the cupboard on the other side of the fridge (see pic).

My layout came from BattleBorn Batteries (see pic).

Challenge can I use the old wires with the new setup so I don’t have to run new/additional wires?


When removing the Converter can I repurpose the wires as follows (see pic)?
1) Use the 6 Ga White wire (yellow) and hook to my Negative Busbar off the battery bank?
2) Use the 6 Ga Red wire (pink) and hook to my Positive Busbar off the batter bank?
3) Use the 8 Ga Copper wire (green) and hook to my Negative Busbar off the batter bank as the main ground for the DC side?

Hitch Jack – would still need to figure out a way to get power out front
a) Since the 6 Ga Red is still hot can I connect it to the 10 Ga Red?
Batteries --> Positive Busbar -->Disconnect Switch --> M4 --> Hitch Jack

7 PIN – would the batteries still get charged since it still goes into “M-4” as long as the AS Battery Disconnect Switch is on ON?
7 PIN --> M4 --> Disconnect Switch --> Positive Busbar --> Batteries?

[jnm30327]

It seems to me that wire is wire. I plan to put the new Multiplus II in the front storage compartment and repurpose the existing wires as follows:

1. Current inverter wire -> AC distribution: repurposed to feed AC-Out 1 from the Multiplus to 50 amp breaker on current panel. I hope it is 3 strand. Neither of the 2 Air Conditioning units nor the hot water heater will be on this circuit so the wire size should be sufficient. Microwave should be the only significant load. I may change out the 2 pole 50 amp breaker to something smaller.

2. Current charger -> DC distribution box: repurposed to feed AC-In on Multiplus from Shore Power socket. 6 gauge wire described above will be sufficient for 50 amp service.

AC-Out 2 will connect to a new breaker box in the front storage. Thence fed on 12/7 wire (0.79" diameter) to the current AC distribution area to feed 3 circuits to the 2 Air Conditioners and hot water heater. This 12/7 wire is the only wire I have to feed from the front storage to the current distribution area. 3 circuits and a ground.

I say all of this not having checked the gauge of the inverter wire. Maybe someone reading this will know the gauge and number of wires.

[jnm30327]

Quick followup. After further investigation, my ideas don't work for repurposing the existing wires for AC use in the lithium upgrade.

The AC side of inverter is only 14 AWG. Not suitable for more than 15 amps.
The Converter wire is 6 AWG, but only 2 conductors. I need 3 for 2 x 120 AC 50 amp.

[AS_Gary]

Bummer jnm30327 - I had hopes that it would work.

Since my repurpose is using the wires gauge already used I think I am going to be ok. I will try it out tomorrow or the next day unless I hear someone say stop

I have researched and researched and it seems right. Fingers crossed.

Gary

[AS_Gary]

Now that I have the Mulitplus II installed I took out the converter and the inverter.

Do I still need the 12VDC PANEL that is located where the inverter was in the front?

[goldenchase]

Originally Posted by AS_Gary

Now that I have the Mulitplus II installed I took out the converter and the inverter.

Do I still need the 12VDC PANEL that is located where the inverter was in the front?

You will need it unless you completely rewire the 12 volt system terminating in the "rats nest". I elected to do it right. Extra storage space was the bonus.

[AS_Gary]

That looks amazing!!

Come do mine, ha