Inverter Install basics

[Nick F]

Thanks for the feedback. I based that diagram on the MultiPlus-II 2x 120V manual (as it was suggested here earlier). That model shows "Load connection AC out1 - From left to right: N (neutral), L2 (phase 2), PE (earth/ground), L1 (phase 1)". So I think it's accurate if I use that model. It also has an AC Out2 which is simply passthrough (not inverted) but short of a separate sub-panel I struggled to figure out how or why to use that in the setup I diagrammed.

I'll think more about the comment about the outlets. On my boat the only outlets that would have an active load on them (if shore was removed) would be the salon stereo, which would only be in standby, and the toothbrush charger in the head (but that would be charged). We don't leave any other AC items on when we're away (the refrigerator is AC/DC). But thinking about it, we don't need the salon stereo on the inverter at all - we use the flybridge stereo when anchored. I'll move that to the other side.

Thanks,
BD

I looked at the Multiplus info. It appears that they offer connections to do the buss-splitting (inverter/non-inverter circuits) inside the unit. You can do it that way, or not, at your choice. Personally I would do it as shown in your diagram (and not inside the inverter).

Another point: The inverter does have 2 x 120V outputs, but only outputs on one of these when inverting (as I interpret the tech data).

 

[BDofMSP]

I looked at the Multiplus info. It appears that they offer connections to do the buss-splitting (inverter/non-inverter circuits) inside the unit. You can do it that way, or not, at your choice. Personally I would do it as shown in your diagram (and not inside the inverter).

Another point: The inverter does have 2 x 120V outputs, but only outputs on one of these when inverting (as I interpret the tech data).

The manual says this: "The MultiPlus-II connects to the neutral and the preferred input line (L1). The power needed to charge the batteries will therefore be drawn from L1.
The MultiPlus-II switches to inverter operation when no AC source is available. The inverter output is 120V single phase. In invert mode, the MultiPlus-II connects both output lines (L1 and L2) together to provide 120VAC to loads on either line.
Any 240V loads will therefore be supplied only when the MultiPlus-II is supplied by a split-phase AC source. This prevents heavy loads such as water heaters or 240V air conditioners from discharging the battery."

So I interpreted that as they both are providing 120. Did I misread that?

BD

 

[Nick F]

The manual says this: "The MultiPlus-II connects to the neutral and the preferred input line (L1). The power needed to charge the batteries will therefore be drawn from L1.
The MultiPlus-II switches to inverter operation when no AC source is available. The inverter output is 120V single phase. In invert mode, the MultiPlus-II connects both output lines (L1 and L2) together to provide 120VAC to loads on either line.
Any 240V loads will therefore be supplied only when the MultiPlus-II is supplied by a split-phase AC source. This prevents heavy loads such as water heaters or 240V air conditioners from discharging the battery."

So I interpreted that as they both are providing 120. Did I misread that?

BD

You are right. Sorry for creating confusion!

 

[BDofMSP]

You are right. Sorry for creating confusion!

Not at all! I'm barely keeping up. I need the input. Thanks.
BD

 

[BDofMSP]

Bottom Line?

OK so I’ve worked to understand, and I think that now I do. The consensus of the forum is overwhelming; essentially EVERYONE seems to think that an inverter / charger with auto transfer is the way to go vs simply adding an inverter and switching it manually. I very much respect the knowledge and experience that I draw upon here, so I am more than a little uncomfortable when I say that I haven’t landed on that conclusion. So rather than saying “I disagree” I’ll simply say “I must not understand”.

The attachment below shows each setup and the various tasks that would be required to perform each install. Tasks that I would rely on a qualified marine electrician to perform are indicated with a dollar sign ($). The rest I’d do myself. The cost of the inverter itself aside (since they don’t seem to be dramatically different within the Victron line), the installation of the 2nd option seems to be significantly more complicated, and has way more work that I’d need to pay someone else to do. I’d also need to order new engraved circuit labels if I wanted a professional looking result when completed.

But it’s not all about money, is it? If the overall solution is superior and the advantages make it worth it, then that’s money well spent. But here I fail to come around, and so I must not understand.

Currently when I take my boat off of shore power, I go to the panel and I flip off each of the AC circuits, then flip the Shore AC Breaker before disconnecting the power cord. In the new Inverter-only world I would still do that, but I’d instead flip the switch from “Shore” to “Inverter”. Voila, I have all of my circuits fed with AC. There is zero additional effort so I don’t get the value behind statements of “it all just fails over automatically” being made. I must not understand.

The other advantage of the inverter/charger approach is that you are ONLY powering circuits that you want connected to the battery. The rest go to the non-inverter fed side of the bus. That advantage I can understand, but it doesn’t seem like a big deal to me. As I mentioned, in the current world I already turn off the individual AC circuits. A simple green dot sticker (for example) would indicate circuits that I don’t need to turn off (or red for vice versa). Managing it seems like zero extra effort compared to now other than looking at the dots when I flip the breakers. I suppose I could look at it differently, as “removing” a step, but I don’t really see it that way. I’m already at the panel – flipping a couple breakers really isn’t hard.

And now is where I really go out on a limb. For a group that is obsessive about redundancy I’m surprised that people are so comfortable with the electronic automatic transfer switch. I see this as a huge single point of failure for me. If that fails I have a bunch of very important outlets that are ONLY powered through the inverter. I feel like I must not understand how that transfer works, because electronics in general seem like things people here don’t trust without backup. My other option removes that single point (or at least changes it to a mechanical switch).

Hopefully someone here can add some insight that helps me understand what others already seem to know.

Thanks!
BD

 

[SteveK]

OK so I’ve worked to understand, and I think that now I do. The consensus of the forum is overwhelming; essentially EVERYONE seems to think that an inverter / charger with auto transfer is the way to go vs simply adding an inverter and switching it manually. I very much respect the knowledge and experience that I draw upon here, so I am more than a little uncomfortable when I say that I haven’t landed on that conclusion. So rather than saying “I disagree” I’ll simply say “I must not understand”.

suppose you got just an inverter. You would manually feed power to the inverter and then manually switch loads to/from the inverter. If a simple inverter is feeding power to a load, say fridge, then neither shore or Gen will feed power until you manually re route the lines.

With an inverter/charger it is automatic. Feed power to inverter charger and it will charge batteries and also pass through current to the loads. Then when there is NO shore power or Gen the inverter takes over and provides power to the loads in the inverter circuit.
Can't get simpler. I am away from boat, it is plugged in, fridge is running. Should shore power fail, inverter takes over for as long as batteries will last. When power returns, batteries get charged.

 

[BDofMSP]

suppose you got just an inverter. You would manually feed power to the inverter and then manually switch loads to/from the inverter. If a simple inverter is feeding power to a load, say fridge, then neither shore or Gen will feed power until you manually re route the lines.

With an inverter/charger it is automatic. Feed power to inverter charger and it will charge batteries and also pass through current to the loads. Then when there is NO shore power or Gen the inverter takes over and provides power to the loads in the inverter circuit.
Can't get simpler. I am away from boat, it is plugged in, fridge is running. Should shore power fail, inverter takes over for as long as batteries will last. When power returns, batteries get charged.

Well yes I get that. But is it not best practice to drop the loads and then the on board main circuit, and finally the pedestal circuit before disconnecting shore power? Or is all this just to allow you to skip that and pull the plug and go? I guess that has some appeal? But that's once a week and part of throwing off the lines anyway. Once I'm out it's almost all gen, which requires toggling the breker anyway.

My fridge is 12/120. It does all that right now. The rest of my need for 120 is 15 minutes in the morning and 15 at night.

Maybe this is a bigger deal for thise with 120 only refrigerators?

BD

 

[Delta Riverat]

My boat has 2 AC switches. One for Shore / Gen-Inverter and another for gen/inverter.

The inverter has been wired to only run the AC outlets and the microwave but as I'm adding the LiFePO4 batteries and the 3 KW inverter, I'm going to wire in the fridge also.

 

[SteveK]

Well yes I get that. But is it not best practice to drop the loads and then the on board main circuit, and finally the pedestal circuit before disconnecting shore power? Or is all this just to allow you to skip that and pull the plug and go? I guess that has some appeal? But that's once a week and part of throwing off the lines anyway. Once I'm out it's almost all gen, which requires toggling the breker anyway.

My fridge is 12/120. It does all that right now. The rest of my need for 120 is 15 minutes in the morning and 15 at night.

Maybe this is a bigger deal for thise with 120 only refrigerators?

BD

Not going to repeat myself so you can re read to find it. Look for how to properly install an inverter charger and then you will stop asking the same question over and over.

 

[BDofMSP]

Sorry. I'm not asking how it works anymore. I've diagramed that and demonstrated that I do understand it. You've personally helped me and I appreciate it.

I'm asking why anyone cares that it works that way. The incremental cost of installation is significant, the risk of having a single point of failure that leaves you with inoperable outlets seems concerning, and all it saves you is flipping a couple switches when you leave the dock? That's what I'm asking - what's the value?

Other people must rely on many more inverted circuits and depart and return to the dock far more frequently than I do. That's the only thing I can think of.

Perhaps there are other advantages I'm not seeing.

BD

 

[Jeff F]

I'm asking why anyone cares that it works that way. The incremental cost of installation is significant, the risk of having a single point of failure that leaves you with inoperable outlets seems concerning, and all it saves you is flipping a couple switches when you leave the dock? That's what I'm asking - what's the value?

Other people must rely on many more inverted circuits and depart and return to the dock far more frequently than I do. That's the only thing I can think of.

Perhaps there are other advantages I'm not seeing.
BD

There are features of a modern inverter-charger that can be really valuable. Here are a few:
- uninterrupted AC for computers etc
- supplementing shore power or generator for peak load handling
- adjusting charging rate to stay within generator or shore power capabilities
- ramping up sudden AC loads like air conditioning to help generator (replaces soft start)

But you haven't asked for any of this. You just want to make coffee without starting the generator.

There is nothing wrong with a 1500w inverter that you plug your ice maker or coffee machine into directly. KISS.

 

[Bmarler]

Well yes I get that. But is it not best practice to drop the loads and then the on board main circuit, and finally the pedestal circuit before disconnecting shore power? Or is all this just to allow you to skip that and pull the plug and go? I guess that has some appeal? But that's once a week and part of throwing off the lines anyway. Once I'm out it's almost all gen, which requires toggling the breker anyway.

My fridge is 12/120. It does all that right now. The rest of my need for 120 is 15 minutes in the morning and 15 at night.

Maybe this is a bigger deal for thise with 120 only refrigerators?

BD

It’s tough to find fault with your approach to manually manage your loads. Those of us with inverter chargers still have to trip the shore power before unplugging. The difference is only that we have the circuits we want live all the time are uninterrupted as the inverter takeover is instant. It avoids the blinking 12:00 on the microwave and the rebooting of the router.
If you don’t have a 120 volt centric lifestyle your approach is perfectly fine.
I know, nice sentence structure. Not gonna fix it.

 

[BDofMSP]

Right! Thank you both. I know that many people, especially liveaboards, would have PCs and other electronics that would not like to be interrupted. Also load management never occurred to me, and who likes to keep resetting the clock!

But it's true that these don't apply in my case, and it does seem like a simple solution would be just fine in my case.

I really appreciate the patience and assistance walking me through all this. Thank you all very much.

BD

 

[Cold Duck]

I tried UPS ( uninterupted Power Supplies) for those critical items I didn't want to reset like the Directv box etc. UPS didn't like the modified waveform from my Honda Generator. So... I just added a small cheap inverter and run it 24/7 on the Directv outlet and anything else I need to not be uninterrupted. Then when switching from Shore/inverter/generator for the major systems, there are no interruptions on those items I want on all the time. Simple, easy and cheap.

 

[ranger58sb]

Or is all this just to allow you to skip that and pull the plug and go? I guess that has some appeal?

Yes, for us all the 120VAC loads are "pull the plug and go."

That's not to say we don't have a routine for switching off shore power and to genset (or not).... but all of that is about our 240VAC loads. Off with the water heater. Off with the (up to) 5 ACs. Off shore power. If we need ACs while underway, on with the genset. On with the ACs and water heater.

But none of that is about our 120VAC loads (like our AC-only freezer and fridge); the auto-transfer in the inverter/charger takes care of that.

When we're not in July or August (mostly), we usually don't need AC underway, so it's mostly just off with the shorepower, get out of Dodge.

-Chris