Inverter choice

[OverboardDavid]

One cautionary note. A Xantrex tech advised me never to run an AC appliance with a current rating higher than the inverter's even when plugged into shore power. In this situation (e.g., an electric water heater) there should be a separate AC bus (switched) that bypasses the inverter completely.

[Sandero]

If you have shore power you want a transfer switch so that AC loads see the shore power and NOT the inverter. Some inverters have built in transfer switches are are wired ALSO to the shore power receptacle. The transfer switch will determine which AC source your ac voltage outlets/appliances "see". An electric water heater should be wired through a breaker to the shore power and not be on the inverter.

[Southern Star]

Caibnsol, the house bank(s) on my Sunstream are mounted under the raised portion of the cockpit where the pedestal for the steering is mounted. It is accessed through doors from the interior companionway bulkhead and has space for my inverter/charger plus 6 x 375 amp/hr Rolls/Surette 6 volt batteries. This moves the weight further forward than the aft cabin steps which should improve trim/balance.

Mine is a freedom inverter/charger and the 120 volt output is wired directly to the 120 volt breaker panel via a selector switch (to ensure that you aren't running 120 both direct from the shore power and from the inverter).

Brad

Brad

[caribnsol]

thanks Brad,

I thought of putting mine in there also, that space is currently mostly storage. My dc panel is mounted on the door to that compartment. I thought about moving the batteries in there but the inverter instructions warned against putting the inverter in the same space as the batteries due to inverter sparking and battery fumes.

I dont have any installed a/c equipment/appliances that I would connect to the inverter. I do have outlets that come off the ac panel and I was planning on putting a manual selector switch for shorepower/inverter. Anything that will run off the inverter will plug into to an outlet.

[Southern Star]

I should check the manual for my Freedom, although lets face it, even the breakers and the battery selection switch can spark if there are problems. Further, starter batteries are generally right next to the alternator (another potential source of electrical ignition). This recommendation is probably wise for Xantrex in terms of potential liability issues, but I question how big the risks are. The gases from the batteries should be vented no matter where they are located, and I have a hose from the bilge blower into that compartment in my boat (although I suspect passive vents, or a solar vent into the cockpit would also suffice).

In any case, this was the set-up on my boat when I purchased it and it was used by the prior owner on a 3 year caribbean cruise as well as for two years thereafter without any apparent difficulties.

Brad

[senormechanico]

Originally Posted by caribnsol

I've got about 3 feet from the panel to where the inverter will be mounted.

... which would probably be 6 or 7 ft. of cable requiring the larger #2 AWG (or #3, if available).

You need full sized wires (both positive and negative) all the way to the source which of course, is the battery bank.
For example, it wouldn't do much good to have AWG 4 to the panel and then AWG 8 to the battery...

Steve B.

[Gary-PHLsuburbs]

I am not an authority on inverters, by any means, but I did happen by a "big box" store today where the Xantrex XPowerInverter 1000 was being sold for $49, with 2.5 length #6 copper cables. The owners guide was informative, as was the company website. This model was designed for RV, not marine use, however it mentioned to not mount the unit "near a bilge." Go figure.

The more sophisticated, and far more expensive, marine units provide enhanced features for marine use, including remote monitoring and long-term exposure to marine environments. For example, this "RV" unit has no GCFI circuit breaker, although you can purchase an "inline" one from a "big box" home store for about ten to twelve dollars.

I agree with others posting to this forum, that the shorter distance to the battery, the better, and in case no one has yet said it, the manual clearly states that only oil resistant clad copper cables, not aluminum, should be used, so the possibility of buying some cheap jumper cables is not a good option. Copper connectors to aluminum wire has been recognised by Underwriters Labratories as a really big problem.

As with any item onboard, it's safe use depends on how you intend to use it, and the safeguards built into the more expensive products are worth it when it's a long swim to shore.

From a practical standpoint, I use a laptop with a 15-inch screen and a DVD player for my onboard movies. It runs nicely on a 200 watt inverter. While a 1000 watt inverter would run an electric drip coffeemaker, a perculator on a propane or gas stove works makes more sense to me. I don't do a lot of cruising on my boat, mostly gunkholing, so my needs may be different from yours, but I wanted to add my two cents about the "big box store" inverters.

Gary

[GordMay]

I haven’t had my hands on a Xantrex charger (inverter) for a long time; but recall (in the 90's) that the captive lugs (DC) were not large enough to accept the factory recommended cable sizes for moderately longer runs.
The, otherwise very helpful, factory “tech” I talked to, couldn’t comment on this dichotomy.

[caribnsol]

I will have to get adaptors for the cable as it will be too big to fit. Started mapping out my dc and charging systems to get a better handle on the whole picture before I start installing. Got busy with non boat stuff so this projcet hasn't been moving very quickly..

[ess105]

Interesting thread. Can anyone help me understand how important pure-sine wave output is on board? I have heard there can be issues and this makes me think I should be preferring a unit that can put out pure-sine. However, I don't want this to be the tail that wags the dog.

For example, if I was buying Xantrex and I wanted a 3kW unit. Is it worth considering the RS3000 over the Freedom?

[Pblais]

Pure sine power is cleaner. Inverter power tends to be square waves. What happens is the edges of the square tend to spike causing little spikes of voltage. It is a side effect of making square wave power. Some inverters do it better and some make pure sine wave forms. Most common appliances don't mind this a little bit. Some electronics don't like it very well and can age faster because of it.

It comes down to the relationship between cost and the amount of inverter power you plan to use and how many things you plan to run. Pure sine power won't have any disadvantages but will cost you more up front. The more toys you run the more important it becomes.

[MidLandOne]

We have always used modified sine wave inverters (or "modified square wave" depending on what way you look at it ) from reputable manufacturers, so not your el cheapo boxes from the local consumer electronics shoppe, and never had a problem with anything. I do not know the exact situation right now with current models but quasi sine wave inverters have traditionally idled at significantly lower currents than sine wave ones (maybe someone has checked that out recently).

Our use includes rotating machines such as power tools, vacuum cleaners, kitchen mixers, etc, etc, AC powered amateur radio transceivers, computers (desktop and notebook), laser printers, and a multitude of chargers for cameras, phones, electric razors, PDA's, etc, etc NiCd/NiMh cell chargers, etc. The only commonish thing we haven't run is a microwave as we are not big microwave oven users but those we know who have done so have had no problem.

For small chargers I on first use make a point of checking that the device is not running any hotter than it normally would just in case. One would expect a hot spot around the filtering if a problem but again never found it to be so. It may be relevant but all our chargers, power supplies, notebooks, are also from reputable companies such as Sony, HP, etc.

On the one occasion I thought we had a problem was when the power supply went on a new TV we put on board (a Sony). I pointed out to them when sent in for repair (honest soul that I am ) that it had been running on an inverter but they immediately responded that did not concern them - the fault was a design one they had run into with that model TV.

I have seen tests of electronic equipment (of types unlikely to be found on a boat) that consistently failed on PWM sine wave inverters (I think they are all PWM now, but stand to be corrected on that) but with no fault on modified sine wave ones. While I would agree that sine wave will generally give a best end use result, assuming one ignores capital cost (and maybe idle current cost), it is not correct to claim as some do that everything will run on a sine wave one.

Interestingly I have seen some anti non sinusiodalists promote using the DC buck converters for powering notebooks (the converters that get you from ship's 12v to the 18.5v or whatever your notebook uses) to among other reasons avoid the use and their claimed potential problems of a non sinusoidal inverter - whereas in fact these boxes are 2 stage ones, the first being a quite messy inverter to convert the 12v to AC, the second converting that to the desired higher DC for the notebook. So perhaps a case of messy inverters can be relied on as long as you don't know they are there .

[bstreep]

We've noticed that some things don't run well on square wave inverters - in particular, cooling fans on appliances.

[camaraderie]

Ran a Freedom25 modified sine wave inverter for 6 years of ful time cruising and powered everything from microwave, LCD TV, Laptop, power tools to small chargers with it. Interestingly...the original very old style (mechanical dial) microwave did not like it but everything else including a new 1000 watt model worked just fine. I purchased base on price and reputation but also because of the high standby amps the sine wave models use.

[MidLandOne]

Originally Posted by bstreep

We've noticed that some things don't run well on square wave inverters - in particular, cooling fans on appliances.

I was unaware that there were square wave "inverters" - have written inverters in " " because such would really be just a chopper. But indeed, if you connect most things up to a square wave you really are absolutely asking for trouble.