So we're considering adding a small inverter. Something just big enough to handle rechaging laptops, cameras, etc.
ProMar's 400PS looks like it would fit the bill quite nicely, plus we could hardwire it in, which would be nice. But I don't understand one of their features (and the company doesn't seem to be responsive). It says that it has "Fully Automatic 10 Amp Crossover Hardwired Connection for AC Output." The 10 amp part is throwing me. I understand (or at least I think I understand) that crossover's are designed to stop AC voltage from going "From" the shorepower "into" the inverter, and that they will automatically switch to inverter energy when the shorepower is disconnected.
But my shorepower connection is 30amp. Does this mean that this "crossover" isn't rated at high enough an amperage to support our (and well 99% of boats) boats shorepower system?
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
This device is suitable for a small boat with no or a small AC system. If you run shore power to the device it will do one of two things:
There is a hardwired provision for the AC outlets and the intention here is to essentially place this device "in series" between the shore power inlet and the main AC breaker on an distribution panel. The internal transfer switch is only rated for 10amp and that’s only about 1200 watts, so wiring this into a Catalina 36 would mean that you’d have to carefully manage your power draw.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Thank you Nick,
This is the part that I'm a little bit confused with.
When you say we would have to "carefully manage our power draw", do you mean that we would have to be careful when using the inverter, or when using the shore power as well?
I get that this unit is rated for a continuous output of 400 watts, and a peak momentary draw of 1000 watts, so we would have to limit our AC usage when running off the inverter. My concern is that my shore power will allow for 30amps, which is 20amps more than the crossover switch is rated for. Your explanation makes me think the switch is similar to a check valve. It will allow for up to 1200 watts to flow from the inverter to the AC panel, and that it doesn't matter what's happening when connected to shore power.
Am I right in my interpretation? Or am I missing the mark? Thanks!
Alex
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Your interoperation is correct:
If the switchover capability was 30 amps, this device would be a no-brainer. But since the safe capability of the internal switchover relay is 10 amps, if you wire this inline you'll have to manage power consumption, even when connected to shore power. The water heater by itself will exceed the 10 amp rating of the switchover relay.
As a side note, information is scant on the 400PS. I don’t know how the 10 amp switchover relay is protected. If I were to install this between my shore power inlet and my main breaker panel, I’d be tempted to put an inline 15 amp fuse on the 400PS AC input hot wire.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Ahh, It's all coming together now. We definitly wouldn't wire it inline. I see this as having "DC IN" from the batteries. And "AC Out"
My plan is to connect it to the batteries, then to run the "hot" connection to an AC breaker. This breaker would be rated for ~10amps (since the unit has a max of 1000 Watts, this gives me a buffer of 1.7 amps). This breaker would then be connected to the hot side of our outlets. I need to look into the connections for the neutral and ground, but I think this will essentially give me a "sub panel" which some people recommend when using inverters.
This will prevent us from ever turning the battery charger or the hot water heater on when the inverter is running (our only other two AC devices).
With this sort of a setup, would the crossover protection continue to protect the inverter, or would we need to go with a source selector switch? (Or possibly a third party crossover switch)
Alex
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Alex. I've deleted the last two comments in this thread because I want to rethink your strategy. It seems that you have decided to keep the water heater and charger ALWAYS on shore power. It also seems like you want to power JUST your outlets selectively using the 400 watts available from the inverter or the 1200 watts allowed from shore power via the transfer switch, i.e., you can live with the 10 amp constraint. If this is correct, then I think I have a simple and safe solution. Let me know if I'm on the mark here insofar as the overall goal.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Almost. We'd like the full 30amps available whenever we're on shorepower (we run a 500Watt heater and a dehumidifier in the winter to keep things from freezing/mildewing), and living aboard means the use of a hotplate, which is about 1200Watts on it's own.
400 Watts just covers at least double our projected "decedent on the hook" requirements. I think I see where you're going with this. Wire the inverter into the outlets, and disconnect them from the shore power all together.
I've thought about this some more, if we do go this route, I think the easiest thing to do is get one of the rotary selector switches. We can wire the shorepower and the inverter to either "side" of the switch. We run the risk of accidently flipping the water heater on and overloading the inverter when we're off the dock, but the inverter has an overload protection feature with a simple reset.
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
I think I see where you're going with this though, and it's a clever solution, it's just too bad this model doesn't have a high crossover threshold!
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Gotch. But you'll find it difficult to find any rotary or multi-pole multi-throw toggle switch with a 30 amp 120VAC rating. You're getting into the range of relays. So for about $80 you can find an automatic full boat transfer switch with the work already done for you. For example: http://gpelectric.com/products/30-amp-transfer-switch
Good luck.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
Thanks Nick, I was looking at that unit earlier, and it's definitely a contender, I'm also looking at the blue seas system rotary switch (http://www.bluesea.com/products/9009/AC_Rotary_Switch_-_OFF_%2B_2_Positi...).
I like the idea of having to physically do something.... It's more likely that we will remember to turn off what needs to be turned off and and turn on what needs to be turned on... and no chance of the inverter accidently draining the batteries if shore power fails.
Update on that, if you want to use a rotary switch you need to have double pole breakers one each source before the rotary switch. Blue Seas also have a panel, that allows you to select one AC Source, and locks out the secondary source, it's really just two double pole breakers. This looks like our best option to date.
Cheers,
Alex
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
From the number of messages back and forth, I can't quite see what you want to do in the end. In one message, you have the inverter hooked up only to a DC source, on another you want to select the AC source (inverter or shore power).
I think you have to determine what needs to be powered from the inverter and from where. You probably have some specific devices you want powered. To do so, you would usually use specific receptacles. How about installing the inverter in line to supply only those receptacles. This way, your normal shore power to the water heater, battery charger, hotplate would be provided through the existing 30A boat system. Only specific receptacles would be supplied through the inverter.
As long as there is no load on those receptacle, the inverter would use very little current so the battery supply should not be affected. And when you need power, those receptacles are always "on" whether from battery or shore power.
Francois Desrochers - C375 Tech Editor
S/V Alizes #15
Lake Ontario
2009 C375
Installing the inverter in line would not require any external protection as it has it's own circuit breaker. The receptacle circuit you would be tying into would have it's own circuit breaker from the existing boat electrical panel; most likely a 15A breaker.
As stated in the manual, you should have a DC switch with in-line fuse near the feed battery for protection and control. The 7" distance can be difficult to meet (ABYC standard). It is usually easier to locate the inverter close to the battery to keep the DC cabling as short as possible. The AC cabling is much smaller size and easier to route.
I just finished installing a Xantrex pro 1800w inverter. It supplies all receptacles one starboard side. Basically wired as I outlined above. It's powerfull enough to run my powerwasher when anchored! That was a pleasant surprise.
Francois Desrochers - C375 Tech Editor
S/V Alizes #15
Lake Ontario
2009 C375
Hi Francois,
That's a good idea, but it unfortunalty it won't work for us. The goal is to be able to use AC power from any outlet when we're away from the dock.
I think the approach that will work for us is to isolate the AC sources from each other. A panel or a selector switch will allow us to do this. When we're plugged into shorepower we'd select the "shore power" input. All AC power would come in from the shorepower, and the inverter would be completely isolated (and unused). When we're away from the dock we'd just throw the switch and the the inverter will power the AC panel.
I liked Nick's idea of a 3rd party crossover, but our concern is that we leave the boat, forget to turn the inverter off, loose shorepower and, inverter takes over, and we kill the batteries. The use of a physical switch prevents this risk.
We're certainly open to suggestions though! We'll make the final call this weekend.
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25
Fair to note that the simplest crossover devices are just AC "source selectors" and usually lack provision to power down a source. You might be looking at one that provides a power-down provision for the inverter when in the shore position, which is excellent. Regardless of how you do it, when not in use or the boat left unattended it’s a good idea to both isolate the inverter from the boat AC system and remove DC power to it. Lots of folks are using non-marine inverters and in a corrosive environment the high-energy step-up circuitry may not be as well protected as in a marine unit.
Install an inverter in a well-ventalited and visible area, away from any chance of water contact. Finally, a typical inverter, even when not driving a load, will pull some power. Rule of thumb is about is about 1 watt DC for every 100 watts of advertised output power. My 1200 watt inverter, which thankfully has cooling fans that only come on when needed, draws about 10 watts no-load.
Nick Caballero
Retired C36/375IA Mk II Technical Editor
With summer upon us we've made up our mind, we're going with a non-hardwired inverter. While there was a lot to like about the Promar, without proper crossover protection it just wasn't worth the extra cost. To add in proper crossover protection would have been too costly for the value it added. We went with a Xantrex PROWatt 600, for a lower price we get a higher maximum output, and it seems to get pretty good reviews. We'll also be adding an automatic crossover. And now that it's installed it works like a champ! Thanks Nick and Francois for all your input.
Alex & Caitlin
S/V Windswept
Vancouver, BC
1985 C-36
SR/FK M25