Information Overload - inverter info please

[rslifkin]

Originally Posted by Brian.D

Be careful on terminology. 'L1' and 'L2' are terms used with 3-Phase power systems and not lines from an inverter or main power on a boat. Unless your boat has 3-phase power, I would recommend calling them what they are, inverter power or AC mains power.

JMHO

Assuming you're responding to my post, my boat has 2 independent shore power inlets each feeding 1 side of the panel. So L1 and L2 are the 2 separate legs of power coming in. In my case, each shore input feeds 1 leg. The generator feeds both legs via the multi pole source selector switch. The inverter only touches the L1 side of the panel though.

[Brian.D]

Got it. You boat is wired much differently, I suspect then that most boats only have a 120VAC service. I believe the way you are describing your boat, you have a 240VAC service which is feeding to different legs in the boat and they may be combining somewhere to support 240VAC equipment.

Or are you running two independent dock power cords to two independent inlets on your stern, providing only 120VAC service?

My apologies to the OP for going off topic.

[rslifkin]

Originally Posted by Brian.D

Got it. You boat is wired much differently, I suspect then that most boats only have a 120VAC service. I believe the way you are describing your boat, you have a 240VAC service which is feeding to different legs in the boat and they may be combining somewhere to support 240VAC equipment.

Or are you running two independent dock power cords to two independent inlets on your stern, providing only 120VAC service?

My apologies to the OP for going off topic.

Mine is connected as 2 independent 120v inlets each with their own cord. It's not a terribly uncommon setup to see. Mine happens to be the older 50A 120v inlets, but twin 30s are also common. As is the 50A 120/240 4 wire connection (which would give 240v and 2 120v legs).

Because I have no 240v, my generator is wired for a single 120v output (instead of 120/240). Both L1 and L2 get connected to the generator in parallel when the selector is set to generator.

[EmeraldCoastSailor]

I bought and installed one of these:
https://www.hodgesmarine.com/prm0720...hoCLAwQAvD_BwE

I would not buy a modified wave inverter. This unit has a feature that easily supports an installation in between the shore power and the AC breaker panel. It powers up all my boat’s outlets. Make sure you install close to batts and use recommended wire size. Have a pro do it if you are unsure. It is critical that the wires, fuses, and connections are done correctly. These units pull a lot of juice from the house bank and as a result could easily start a fire if not done right.

[kirklkjb]

Defining the goals and prioritizing what is needed vs what is required and the budget will help more than figuring out the inverter. Once goals are defined a power budget can be derived for ease use case. I.e At the dock, on the hook during the day, on the hook at night. May want to consider locations also.

With a nearly 2k per month for dock fees the pay back may be reasonable.

Being self sufficient is not easy. You need to recreate all the services abroad as you have ashore.

[Dieseldude]

Originally Posted by Cap Morgan

Thanks for your assistance in advance. Can someone point me to a link on this site that explains how DC to AC inverters work on Sailboats, costs etc. I searched the site but am often faced with too much information when I search.
Here’s what I’m trying to accomplish. Obviously, every Cruiser has an AC electrical system and a DC system. I’m working on upgrading my DC system with the addition of new Solar panels while repairing my Wind generator. I’m shooting for approximately 540 volts DC combined between solar and wind. On the other side of the coin I’ve got things like an air conditioning system that I think only works when I’m plugged in at the dock ( possibly wrong on this) and outlets that like wise work only when I’m on shore power. I’m not ever planning to use slips for my boat in Miami ($1750 per month for my boat at Dinner Key Coconut Grove). Hence, Id like to be able to use my AC electrical system in the boat once in awhile on my mooring and at sea to run things like a vacuum cleaner and other appliances that work off the AC outlets when I need to. I’m simply seeking a link to posts that I know must exist on this site regarding this topic. Thanks again!

I think that you really mean that you are aiming for 540 watts, not volts, since DC systems aboard small vessels are normally 12 or 24 volts. Consider that a standard 120 volt household outlet can supply a maximum of 1800 watts before the breaker trips. This equates to 2.4 horse power, which is useful to know for electric motors. But due to inefficiencies, it will not reach this much. And this assumes that the voltage is 120, but it could be lower. You will need to sum up the consumption of all equipment that you plan to run at the same time to determine rating of the inverter required. For estimating DC charging capacity compared to AC load, consider a total load of 1500 watts. 1500/500=3. A 500 watt solar array would need to charge the batteries 3 hours for every hour of consumption. This assumes maximum sun light is reaching the array.



Another thing to consider is that watts is not the full story on power requirements. Watts is the full story only for purely resistive devices such as heaters and incandescent lights. But electric motors and transformers have a complication called power factor. They actually pass more power in watts than they develop into useful work. This is an inefficiency. The closer the power factor is to unity, or 1, the less is the effect of power factor. Power factor is the reason that power consumption or capacity of many devices is quoted in volt amps, as this unit is independent of power factor. Power factor is normally noted on the data tag of electric motors. But for consumer market equipment, it may not be included.



Without getting bogged down with electrical theory and math, try and get the power consumption of your devices in volt amps rather than watts, and you cannot go wrong. If this info is not available, just add about 15% to all loads that are primarily electric motors, or that have internal transformers, and if their consumption is in watts. This should cover most discrepancies. Most electronic gadgets have an internal transformer, so they have a power factor of less than one. If you want to calculate more precisely, there are some good web sites that explain power factor in more detail than is practical on this forum. A good quality inverter should have its capacity spec in volt amps. You do not necessarily need to understand the electrical theory in detail. Just the arithmetic is sufficient.


There have been some good posts about pure sine wave versus modified sine wave inverters. Pure sign wave inverters cost a lot more than modified sign wave. But a pure sign wave is required for a lot of gadgets. Attempting to run some things on a modified sign wave, will cause poor performance, or could even damage some items. Bottom line is that to reliably run any load, a pure sine wave inverter is recommended.


Under heavy loading, an inverter will run quite warm, so it needs good ventilation. Not a good idea to tuck it away inside a small compartment.

[Mauruuru]

I do not understand why you are developing a 540V DC system. High voltage DC systems require special attention to isolation and fusing. Your focus should be first on sizing the load you intend to supply for what length of time. Batteries are rated in AH (ampere-hours) of discharge at the rated voltage for specified levels of discharge. Of course for a given voltage rating battery physical size will be influenced by the AH rating as well as the chemistry chosen but that shouldn't be driving you to such high DC voltages.

On the AC side, figure out what the biggest AC load you will run concurrently in Watts (or more correctly Volt-Amperes) and select an off the shelf inverter that provides those Watts at the necessary DC input voltage and the AC output voltage.....the manufacturers manuals are a good source of info...