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Installation of New Inverter
Hello Everyone,

The solar upgrade project continues.  I'm starting to plan the installation of our new inverter.  It's a Victron Multiplus 12/3000 (12 volts, 50 amps, 3000 KVa (basically 3000 watts).  It is an inverter/charger.  I understand that the charger part of this unit will take over the function of the converter, which could then be removed.  Is this correct?

The connections to the battery and ground are simple enough, but I'm hazy on how to connect this unit to the main service panel.  I'm pretty sure that the transfer switch (shore/generator) output will have to be directed to the inverter a/c in, and then the inverter a/c out will be directed back to the a/c side of the service panel. 

With no converter, how will I power the 12 volt side of the service panel?  I'm guessing that I will have to have a separate connection from the battery back to the 12 volt side.  Is this correct?

I'm sure that some of you have done this, perhaps even with the same or a similar inverter.  Please let me know where I have things wrong.

Thanks,

Tim
2014 Mid-Bath
2014 Honda CRV toad
Re: Installation of New Inverter
Reply #1 –
Assuming the Victron inverter/charger is the same as other through-inverters, the 12-volt fuse panel is still connected directly to the battery with a large gauge wire., the new charger can replace the converter.
The new charger's positive cable can be connected to the battery's main fuse, its negative cable goes to the battery capacity meter's shunt.
If desired, the old converter can be left in place for faster battery charging when shore power is available or used as a backup charger. It could be handy for use in the winter during long periods of rain when generator time is needed to top off the battery, allowing charging at around twice the rate of what the charger alone can provide.
A battery pack as large as what your LD has can safely absorb a lot of amperage, much more than 50 amps.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
 
Re: Installation of New Inverter
Reply #2 –
Hi Tim;  The 3kw inverter will want to draw about 240 Amps at full load.  Enough to run the roof Air Conditioner. Edited: 70A each is the charge current.  As Larry states, the 3 batteries can easily source 80A each.  That would take 0000 cables (4 ought).  RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Installation of New Inverter
Reply #3 –
Quote from: RonB  - 
Hi Tim;  The 3kw inverter will want to draw about 240 Amps at full load.  Enough to run the roof Air Conditioner.  Just 3 batteries at 70 Amps each is only 210 Amps.  That would take 0000 cables (4 ought).  RonB

240 amps isn't a high rate for three 206AH SOK, they are rated at 170 amps max discharge for each battery for a total of  510 amps maximum.
I used flexible 0000 gauge welding cable on one LD, bending and routing normal 0000 cable is very difficult.
Crimping lugs this large should use a large, pro-grade crimper.
I used to use a hammer crimper for field work but the crimps were not up to grade and caused poor connections within a year or two. For later projects, the right crimper was purchased. Well worth the money.

Old hammer crimper


Pro-grade crimper and cable cutter



Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Installation of New Inverter
Reply #4 –
Sorry, it was late.  The SOK's are down to $958 (Amazon), are UL certified, and have internal heaters and Bluetooth included.  I'm happy with my (two years so far) older models.  Two of the metal cased ones can be fit into the standard battery box. Fine stranded welding cable is the best to work with, and a handle type crimper is easier to use and safer.
 RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Installation of New Inverter
Reply #5 –
Thanks for the replies.

Step one for me is a thorough understanding of the existing electrical system, so I've been studying the electrical schematic diagrams in the back of the Lazy Daze manual. 

Diagram #3 shows the inputs from shore power and generator going to the 120 VAC side of the power center.  It's a simplified diagram, and does not show a transfer switch between these two inputs and the power center, but I assume that there is one.  So both inputs go into the transfer switch, and the output from the switch goes to the power center, correct?

As I understand it, I need to take the output from the transfer switch and route it to the A/C-in port on the inverter, then return from the inverter A/C-out port back to the 120 VAC side of the power center - essentially looping from the transfer switch output through the inverter back to the power center.  Is this correct?

I don't have the new battery bank installed yet, so I've plugged in shore power.  Even with no house battery, the 12 VDC side of the system is powered.  I assume this is due to the existing converter, which implies that the converter is also powered from the output of the transfer switch, and there is a connection from the converter to the 12 VDC side of the power center.  There is also a 6 gauge wire running from the 12 VDC side to the house battery, and when there is no generator/shore power, this is how we get power from the battery bank to the 12 VDC side.  This same 6 gauge wire also will supply charge to the battery when we do have generator/shore power.  Have I got all of this right?

It sounds to me like it's best to just keep the converter in place.

Thanks in advance for any replies,

Tim



2014 Mid-Bath
2014 Honda CRV toad
Re: Installation of New Inverter
Reply #6 –
Quote
So both inputs go into the transfer switch, and the output from the switch goes to the power center, correct?

Yes, exactly although the LD setup is a little different than what I've seen before. The yellow arrow in this photo shows the transfer switch. The turquoise arrows where the wires attach that are the output from the transfer switch. Mine were 10 gauge stranded and about 10 inches long. They pass through to the front of the unit where the hot attaches to the breaker and the neutral to the neutral bar.
jor
09 27' MB
10  Suby Forester
Re: Installation of New Inverter
Reply #7 –
Tim,

Here's a better photo showing the transfer switch output wires.
jor
09 27' MB
10  Suby Forester
Re: Installation of New Inverter
Reply #8 –
A bit uncertain how you have things hooked up, but of course the converter must be switched off if the whole-house inverter is powered on. By corollary, you cannot power the inverter FROM the converter if the house batteries are not installed.

Steve
2004 FL
2013 Honda Fit
Re: Installation of New Inverter
Reply #9 –
Quote
but of course the converter must be switched off if the whole-house inverter is powered on.

On mine, I plan on leaving the converter breaker in the off position when using the inverter. However, I plan to wire up a contactor switch so that I can just leave the breaker in the on position. When the inverter is turned on the converter will switch off.

I'm anxious to hear how Tim wires up the inverter-charger as I think this would be a good way to go and a fun project.
jor

09 27' MB
10  Suby Forester
Re: Installation of New Inverter
Reply #10 –
Steve,

You mentioned that if the inverter is switched on, the converter must be switched off.  What will happen if both are on at the same time?

The inverter that I have (Victron Multiplus inverter/charger 12V 3KVA) is a through inverter with a charger, so it pretty much takes over the function of the converter.  I think what most people do in this case is remove the converter, or at least disconnect it.  From your comment, it sounds to me like this is not a choice - it must either be disconnected/removed, or a transfer switch must be installed to force it off when the inverter is on.  In this case, disconnection/removal is simpler.  Do you agree?

Thanks,

Tim

2014 Mid-Bath
2014 Honda CRV toad
Re: Installation of New Inverter
Reply #11 –
If the converter is on when the inverter is on, the converter will try charging the battery using battery power, not an ideal situation.  The converter must be off when the inverter is operating.

The converter can be on when the generator or shore power is available, as I mentioned in an earlier post, the 50-amp charger is small compared to what the large lithium battery can handle.  I'm surprised the charger is so small, the old Xantrex 2000-watt
inverters had 100-amp chargers.
I would leave the converter in place for use when the battery needs a deep charge and only generator power is available. Combining the converter with the charger will double the charge rate and cut the charging time in half.

Leaving the converter in place causes no harm if left off when the inverter is on.  It's your choice what to do.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Installation of New Inverter
Reply #12 –
Forgot to mention the hidden circuit breaker that is located somewhere between the battery and the Power Center.
The cheap circuit breaker is prone to failure and can suffer from high internal resistance as it ages, I would replace it was a more robust breaker or a fuse.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Installation of New Inverter
Reply #13 –
Quote from: T&F  - 
Steve,

You mentioned that if the inverter is switched on, the converter must be switched off.  What will happen if both are on at the same time?

Actually, the first time I turned on our inverter I found out. The inverter powers the converter which then tries to charge the batteries - which are  powering the inverter. With no load, it may be ok, but if feeding a microwave, where the inverter pulls 140A from the batteries and the converter is trying to put 55A back in the batteries, the inverter then has to draw MORE power from the batteries, and you get power looping and voltage drops that cause oscillation cycling the inverter on-off.

Steve
2004 FL
2013 Honda Fit
Re: Installation of New Inverter
Reply #14 –
Larry - that's a good suggestion, I think I will leave the converter in place.  I can just manually turn in on and off, although it would be much nicer to just leave the switch on and have a transfer switch upstream, as Jor intends to do.  By the way, I pulled the power center out to have a look and it, and I find it intimidating.  Perhaps this will change as i have more time to think about it, but if I need to hire a professional, I will certainly have them use a transfer switch.

Also, you mentioned a cheap fuse that should be replaced: is this the 50 amp circuit breaker on the 6 gauge cable that runs from the power center to the battery?

Steve, thanks for the explanation of what I think I've read about called the "inverter/converter death loop".  I understand it better now.
2014 Mid-Bath
2014 Honda CRV toad
Re: Installation of New Inverter
Reply #15 –
Quote from: T&F  - 
i
Also, you mentioned a cheap fuse that should be replaced: is this the 50 amp circuit breaker on the 6 gauge cable that runs from the power center to the battery?

That's the one

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Installation of New Inverter
Reply #16 –
Now that the inverter is installed and the DC connections have been made to the busbars, it's time for the AC connections.

As I mentioned before, it is a Victron Multiplus inverter/charger, so it has an AC-in port as well as an AC-out port.  I will need to connect the AC-out port to the main panel, at the location where the output of the generator/shore transfer switch is now connected.  The AC-in port will need to be connected to the output of that transfer switch. 

I'm assuming that 6/2 is the wire to use for this.  Connecting it to the two ports on the inverter seems straightforward, but I'm at a loss on how to connect it to the panel.  I think I will have to use a small junction box to connect the transfer switch output to the wire back to inverter-in, but I have no clue how to connect the inverter-out wire to the panel (I've never wired a panel).

Any information would be greatly appreciated.

Thanks,

Tim
2014 Mid-Bath
2014 Honda CRV toad
Re: Installation of New Inverter
Reply #17 –
6-gauge wiring is not needed for the Inverter's output connection to the transfer switch. With a 3000-watt inverter, its output will not be over 30 amps.
10-gauge wire is used for 30-amp, 12-VAC loads.
https://contentgrid.homedepot-static.com/hdus/en_US/DTCCOMNEW/Articles/THD-Pro-WireGuage-Section3-Chart-WF-3567952.png

The inverter never directly connects to the Power Center, it connects to the transfer switch
The connection between the inverter and transfer switch can be made inside a junction box if room allows.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Installation of New Inverter
Reply #18 –
Larry,

Okay, 10 gauge it is - much easier to work with than 6 gauge.

I'm confused about your comment that inverter never connects to the panel directly.  My inverter also contains a charger, and is designed to receive AC from generator/shore (output of the transfer switch).  My understanding is that it uses some of this power to charge the battery and turns the rest of it around, back to the power center.  This is why I've been thinking that I need to disconnect the transfer switch output from the panel and route it to the input AC port on the inverter, and then route a second wire from the AC output port on the inverter back to the panel.  The connection back to the panel will also provide power to the panel when the inverter function is enabled.

Please let me know whether any of this makes sense to you.

Thanks,

Tim

2014 Mid-Bath
2014 Honda CRV toad
Re: Installation of New Inverter
Reply #19 –
Well, spent a bit of time looking at Victron's owner's manual and didn't find any information on using a transfer switch. It is a confusing manual that would take many hours to read and understand. It's been a few years since I wired a pass-through inverter.

I was wrong about the inverter not connecting directly to the Power Center.
Leave the transfer switch wired as is except for having the transfer switch's output go to the Inverter's 120-VAC input instead of the Power Center.
Wiring the Inverter's output directly to the Power Center's input (hot bus for the breakers) provides power for battery charging when shore power or the generator is available.

The connections can be made inside the Power Center, there are extra punch-out openings in the rear of the Power Center that allow adding the extra wiring.

Larry



Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Installation of New Inverter
Reply #20 –
I connected the inverter to a second transfer switch which has the generator input of the original transfer switch as the second input. Output goes to the former generator input of the original transfer switch. Works very well except for the four minute delay when you turn on the inverter.
Harry 2006RB
Re: Installation of New Inverter
Reply #21 –
Quote
Works very well except for the four minute delay when you turn on the inverter.

You might be able to eliminate that delay with a jumper. I have a GoPower TS-30 as my second inverter. After jumping two pins no more delay.
jor
09 27' MB
10  Suby Forester