Inverters

[Matt sachs]

So,( just thinking out loud) Shore power only runs the chargers. Every thing onboard runs off the banks so the charger needs to be able to handle the entire load I apply to the bank while on Shore power?

I dont want to be making hot water unless the engine is running (engine heat)or pluged into SP (120V), so Is the simplist thing just to unplug the water heater when sailing? Is there a charger / inverter that has a 120V circuit thats only hot when SP is connected?

[Dockhead]

Originally Posted by Matt sachs

So,( just thinking out loud) Shore power only runs the chargers. Every thing onboard runs off the banks so the charger needs to be able to handle the entire load I apply to the bank while on Shore power?

I dont want to be making hot water unless the engine is running (engine heat)or pluged into SP (120V), so Is the simplist thing just to unplug the water heater when sailing? Is there a charger / inverter that has a 120V circuit thats only hot when SP is connected?

Yes, my Victron has a separate circuit for the hot water immersion heater (and any other load you want to shed when there's no shore power present). If shore power is not present, this circuit is shut down automatically.

Also, you set the amount of power it is allowed to draw from an external AC source (shore power, or generator). If there is more demand than the limit you set, then it starts cutting down the power going into the battery charger. If that's still not enough, then it will invert power from the batteries to supplement the external power source.

I am pretty sure that Mastervolt does the exact same thing, and there are probably others. I would insist on these features -- they are tremendously useful.

The only downside is that it requires all your AC power to go through the charger/inverter, which may require some significant rewiring. Also, if you have a failure of the charger/inverter (as I did), you lose all AC power! But still these features are so useful, that it's worth the risk of this IMHO.

[colemj]

You will want to have low and high AC loads separated at your AC panel. Then just feed the low load side with the inverter. That way, your inverter is never running the high load stuff like the water heater off the batteries.

Mark

[Matt sachs]

Thanks guys, this is starting to make sense. Does having a 120V inverter circuit and a 120V SP circuit cause any grounding issues in a steel boat? Are the modern chargers compatable with 50 and 60 Hz?

[Dockhead]

Originally Posted by colemj

You will want to have low and high AC loads separated at your AC panel. Then just feed the low load side with the inverter. That way, your inverter is never running the high load stuff like the water heater off the batteries.

Mark

That will work great with a simple inverter. But not recommended with an inverter/charger which has load limiting and/or power boost -- because the inverter/charger will not be able to take into consideration those loads, which will defeat the purpose of those functions.

Moreoever if you have an inverter/charger with a load-shedding circuit, then it will switch the hot water heater back on automatically when there's enough shore power to run it. This is really handy.

[Matt sachs]

With the Victron load shedding inverter, can you select which circuits are shut down?

[Dockhead]

Originally Posted by Matt sachs

With the Victron load shedding inverter, can you select which circuits are shut down?

Well, of course. You have to install it, after all! Just hook up what you want to that circuit. Immersion heater, any electrical heaters, etc.

[colemj]

Yes, the Victron has two circuits - one 50A primary transfer-switched circuit and the other a 16A non-transfer switch (load shedding).

For us, the problem is in implementation. I'm not interested in the load sharing, because our inverter and shore power run the AC and water heater just fine without help. However, if I run those circuits through the primary circuit on the Victron, then if shore power goes out (a extremely common occurrence in the few marinas we have been in) or the generator quits or trips its circuit, then all of that load hits the batteries. If one is not right there staring at the panel when it happens, then those batteries will be run flat in no time.

This doesn't make sense to me.

On the other hand, 16A isn't enough to run those high output devices through the non-transfer switched circuit, and that circuit isn't load-sharing. So it is useless to us.

Instead, we use the 50A transfer switch circuit on the low load side of the AC panel and
leave the high load side unconnected to the inverter.

What we would ideally like is a transfer-switched circuit to handle the low load side, and a non-transfer switch power sharing circuit for the high load side.

In other words, when the power is cut, the low loads transfer to the inverter and the high loads get dropped. And when the power is on, the high loads can use the power-assist feature.

Of course, the user manual is written in Sanskrit and is printed using 3pt font (seriously - the whole manual is a 4"x3"x1" book with tiny, tiny type), so it is possible that it can be set up like I want, but I have not figured out how to do so.

As an aside, Victron supplies the worse documentation in the most obscure descriptions and language you will find in any manufacturer. I have met power engineers who work constantly with Victron products who still struggle with the manuals.

Mark

[Matt sachs]

Originally Posted by Dockhead

Well, of course. You have to install it, after all! Just hook up what you want to that circuit. Immersion heater, any electrical heaters, etc.

I may still be a bit confused. The inverter supplies 120v to the AC side of my distribution panel. I suppose the load shedding circuits attach directly to the inverter?

[Matt sachs]

I like redundancy so hows this for a plan. Shore power to the chargers.Two 15 amp 120V circuits completly seperate from the 12v system that are only hot with SP. A properly sized house bank (size TBA) The 12v system is fairly straight forward. Cranking battery seperate from house bank. Two or three or more of the smaller inverters to run specific items that can be moved around if one fails. For what they cost I could even keep a spare tucked away somewhere. I would hate to have one item fail that made the entire thing not work. Any thoughts?

[exMaggieDrum]

Originally Posted by wellin

You need to add up the watts of all 110 volt equipment you want to run at the same time and then get an inverter with about 1.5 times that for output. So if for example your 6 guests are girls that want to blow dry their hair at the same tome it would be 1500w times 6 or 9000 watts times 1.5 for safety is 13,500 watt inverter. Or if they could take turns maybe a 2000 watt would be just right.

Mine is a TrippLite not really a marine unit but it was free and has 2000w output a 100amp multi stageb charger and automatic generator starting interface. Not recomending you use a non marine quality but mine works great.

Sent from my SCH-I415 using Cruisers Sailing Forum mobile app

I wouldn't recommend using a non-marine inverter. The marine ones handle the neutral bonding different than what the non-marine ones do. A safety issue. Your comments about sizing are good. I will make another comment in another post about what uses they are appropriate for and some gotchas to consider.

[exMaggieDrum]

Originally Posted by colemj

Yes, the Victron has two circuits - one 50A primary transfer-switched circuit and the other a 16A non-transfer switch (load shedding).

For us, the problem is in implementation. I'm not interested in the load sharing, because our inverter and shore power run the AC and water heater just fine without help. However, if I run those circuits through the primary circuit on the Victron, then if shore power goes out (a extremely common occurrence in the few marinas we have been in) or the generator quits or trips its circuit, then all of that load hits the batteries. If one is not right there staring at the panel when it happens, then those batteries will be run flat in no time.

This doesn't make sense to me.

On the other hand, 16A isn't enough to run those high output devices through the non-transfer switched circuit, and that circuit isn't load-sharing. So it is useless to us.

Instead, we use the 50A transfer switch circuit on the low load side of the AC panel and
leave the high load side unconnected to the inverter.

What we would ideally like is a transfer-switched circuit to handle the low load side, and a non-transfer switch power sharing circuit for the high load side.

In other words, when the power is cut, the low loads transfer to the inverter and the high loads get dropped. And when the power is on, the high loads can use the power-assist feature.

Of course, the user manual is written in Sanskrit and is printed using 3pt font (seriously - the whole manual is a 4"x3"x1" book with tiny, tiny type), so it is possible that it can be set up like I want, but I have not figured out how to do so.

As an aside, Victron supplies the worse documentation in the most obscure descriptions and language you will find in any manufacturer. I have met power engineers who work constantly with Victron products who still struggle with the manuals.

Mark

I won't address the power-assist feature. But regarding the low versus high load circuits, the way I would recommend is to wire the high loads for shorepower only and the low circuits on the inverter shorepower/inverter transfer switch. BUT - you need to "split" the neutral bus in the panel so that the neutrals for the high loads are not shared by the neutrals to the low loads that are on the inverter output side. The high loads neutrals are then not on the same buss as the inverter output. This is because the shorepower is bonded to ground at the head of the dock. You should not also bond the neutral to ground again on the boat except when the shorepower is disconnected.

The inverter (a marine one) should manage this with its internal neutral bonding switch. When shorepower is input, it passes on the neutral and doesn't bond to the ground circuit. When it is inverting (no shorepower input) it bonds the neutral to the ground since it is the source of AC.

The same is true for gensets, except that a easiest and safest install for a genset is to have a either/or AC switch so that both shorepower and generator cannot be on at the same time. A complexity that I don't recommend is those inverters which can reverse AC back to the grid (i.e. shorepower in this case) but this involves very complex synching of the AC frequency. This should never be set up on a boat. It is dangerous as it would make the shorepower inlet plug hot and it is a male plug which can be touched by wandering fingers or odd bits of wet AC transmitting things.

Splitting the neutral buss is a non-trivial exercise since neutral wires are rarely (never) labeled. We would use an AC clamp-on ammeter to identify those by turning on and off each circuit breaker one at a time, making sure there was an actual load working on the load side so power would be seen when it was turned on. Then we moved those to a separate neutral buss. This is not for amateurs especially those with engineering degrees. (Just kidding but the many of the worst wiring nightmares I worked on were done by engineers who were outside of their skillset, even electrical engineers. Boats are a special subset in the electrical world.) It's not undoable by amateurs but it requires a great deal of info and care. AC can kill you. DC can burn up your boat but it won't kill you outright like AC can. Plus, you can fry your inverter if you miswire it.

Right now our new boat has an overly complicated Trace inverter. I will reluctantly deal with it as I will only use it for basic inverting and charging. The documentation is daunting though and I have worked on many of them. I would prefer a much simpler type. It is way too complicated for my needs. My mantra is keep things as simple as possible. I don't use power boosting and AC sharing for example, even if it is built-in. I don't like automatic starting of gensets either but that is a useful feature for some folks I guess. I want to turn things on and off myself. Also beware when using the "search" function feature on some inverters to save power. An AC circuit you think is off can turn on just when you are replacing the outlet. If you have this feature in your inverter you should carefully research it and understand how it works and how to turn it off if needed.

[colemj]

Originally Posted by exMaggieDrum

I won't address the power-assist feature. But regarding the low versus high load circuits, the way I would recommend is to wire the high loads for shorepower only and the low circuits on the inverter shorepower/inverter transfer switch. BUT - you need to "split" the neutral bus in the panel so that the neutrals for the high loads are not shared by the neutrals to the low loads that are on the inverter output side. The high loads neutrals are then not on the same buss as the inverter output. This is because the shorepower is bonded to ground at the head of the dock. You should not also bond the neutral to ground again on the boat except when the shorepower is disconnected.

The inverter (a marine one) should manage this with its internal neutral bonding switch. When shorepower is input, it passes on the neutral and doesn't bond to the ground circuit. When it is inverting (no shorepower input) it bonds the neutral to the ground since it is the source of AC.

The same is true for gensets, except that a easiest and safest install for a genset is to have a either/or AC switch so that both shorepower and generator cannot be on at the same time.

Yes, this is how our electrical system is designed and implemented. However, it doesn't help in taking advantage of some of the Victron options. I don't think Victron has thought out their power sharing and no-transfer auxiliary systems well. I cannot figure out how to wire it so that the inverter has no chance at all of putting the high loads on the batteries if the shore power or generator is cut. Why anyone would want that risk is also something I cannot figure out.

On the other hand, I could be missing something completely obvious.

Mark

[s/v Beth]

That's all nice about vitron, but who makes the most bombproof sine wave inverter?

[Dockhead]

Originally Posted by Matt sachs

I may still be a bit confused. The inverter supplies 120v to the AC side of my distribution panel. I suppose the load shedding circuits attach directly to the inverter?

Yes, the water heater cable will need to be connected directly to the inverter. This can mean a bit of PITA rewiring, and in fact I don't have my water heater hooked up this way because I just didn't have time for all that.

Will your AC panel accomodate a separate power input for one circuit, or does it have a bus bar? Mine has a bus bar, so PITA. I would have to drop a separate cable from the inverter and install a separate switch and breaker for the water heater. It wasn't worth it for me, although I keep thinking I'll get around to it maybe some day.

If your AC power will accept a separated input for one circuit, then it's easier -- all you need is another cable from the inverter to your AC distribution panel.