Inverter Size and Possible Transfer Switch

[sailingharry]

Originally Posted by Pete7

One other point we haven't mentioned, I am pretty sure you will need a pure sine wave inverter for a microwave. Those huge cheap e bay inverters aren't going to do it.

Yes, and no. Our '98 boat came stock with a microwave and a Freedom 10 inverter. "Modified Sine" (at best! LOL). 23 years later, we still microwave on a regular basis. My sister spend a few months in a conversion van, and we hooked up an ultra small microwave to a 700W ultra cheap inverter, and even thought the inverter howled with warnings every time she used it, it took her across the US and back. So, yes, it will work (and to Dockhead's point, most inverters may not run continuous at full load, but most will put out double rated for a few minutes -- it takes a few minutes for our 1KVA unit to trip if my wife forgets and runs the toaster and coffee pot at the same time -- around 3 KW).


But the "no" part. From what I have heard (here? with a frequent poster? maybe Trente or Pelagic or Jedi?) a microwave has significant reduction in output from a modified sine. And we certainly suspect that is true (but haven't done the tear/compare that the member I mention has done). It is rock solid with resistive load like a coffee pot or toaster, and seems to do just fine with nuisance devices like laptop and cordless tool chargers.


Note, this winter is likely to finally see it get upgraded.

[Frankly]

Jim,

I have been using a 1KW Renogy PSW (rebadged AIM) IC for several to run a small microwave and a coffee maker. It has worked without issue and even trips off line if I absent mindedly try both at once.

I remoted the control panel and just switch it off when not in use. I feed it from the Battery Charger Breaker on the IP panel and separated the two receptacle circuits to feed from the inverter. I split the neutrals back in my old Xantrex days so just left that in place. Don't remember if the Renogy requires the separate neutrals. You could just wire it up for a dedicated receptacle and forget the transfer switch/ feed business. Cheap enough you could have a spare for the Yucatan.


Frankly

[jpstevens]

Thanks to all the the posters for an excellent discussion.

[s/v Jedi]

Originally Posted by sailingharry

Yes, and no. Our '98 boat came stock with a microwave and a Freedom 10 inverter. "Modified Sine" (at best! LOL). 23 years later, we still microwave on a regular basis. My sister spend a few months in a conversion van, and we hooked up an ultra small microwave to a 700W ultra cheap inverter, and even thought the inverter howled with warnings every time she used it, it took her across the US and back. So, yes, it will work (and to Dockhead's point, most inverters may not run continuous at full load, but most will put out double rated for a few minutes -- it takes a few minutes for our 1KVA unit to trip if my wife forgets and runs the toaster and coffee pot at the same time -- around 3 KW).


But the "no" part. From what I have heard (here? with a frequent poster? maybe Trente or Pelagic or Jedi?) a microwave has significant reduction in output from a modified sine. And we certainly suspect that is true (but haven't done the tear/compare that the member I mention has done). It is rock solid with resistive load like a coffee pot or toaster, and seems to do just fine with nuisance devices like laptop and cordless tool chargers.


Note, this winter is likely to finally see it get upgraded.

Exactly, the microwave will run, just a little rougher (you can actually hear that the power isn’t clean) and the power is reduced. This is easy to see by comparing the time it takes to bring a cup of water to a boil on inverter vs shore power or genset.

I remember in Panama, the shore power was very dirty (distorted sine wave) and the A/C made a lot of noise. When shore power went out and we run on genset, the A/C went quiet with the cleaner power (good inverter is cleaner than a genset).

[Fuss]

I had a 1500watt Victron inverter that I boiled the 2100 watt kettle with for years…the red overload blink light came on and the kettle boiled…what more could you want….I now have 2 multipluses in series for a max of around 5000 watts

[botanybay]

As a reference point, I have a Victron 1200 VA 110v inverter installed to provide limited power to outlets throughout the vessel in addition to the 8kva Victron Quattro to provide 230V power.

I purchased a 900 watt microwave and it would "pulse" on and off, flickering the internal light and causing alarming on the 1200 watt 110v Victron inverter.

I replaced the 900 watt microwave with a 750 watt microwave and it is right on the edge. The inverter does occasionally alarm and the light in the microwave occasionally flickers. If I have anything else (small) running it can be a problem.

I do think that the microwave is slowly being stressed as after a couple of years it flickers and occasionally makes additional "odd" noises but continues to work.

I CAN run a Kurig "Rivo" to make expresso drinks without any issue, it claims to be 1100watts (from memory), it might actually be a bit higher.

As noted previously, this is tied to inverters being rated in VA not WATTS. for a resistive load VA = Watts. For a microwave VA < Watts due to power factor.

Due to the physical size difference between the 2000VA and the 3000VA Victron 110v inverter I plan to have a 3000VA Victron inverter dedicated to the Galley, a high power service outlet near the companionway and a plug for the washer/dryer (I was planning on a 230v washer/dryer on the big inverter but was able to obtain a 110v version used).

All inverters have a remote turn off for each inverter so the idling loads are minimal in practice assuming the inverter is turned off when not in use.

I do leave the small inverter for the Nav station online all of the time (300VA Victron inverter).

[steffan]

Originally Posted by Anders

750W is the output. The input will be higher, probably ~1200W.

I can confirm this. Our 1000w continuous/2000w peak rated inverter is rarely able to power our 750w(?) rated microwave (the lowest power cheapo one we could find). MW pulls about 1100w.

[captainwd40]

PureSine makes a great 3000 watt charger inverter and it is very easy to install. Shore power connects at the input your breaker panel connects connects at the output and it automatically switches between battery/invert and shore power charging/pass thru AC power.

Cheers!

[Silver_Surfer]

its been pretty confusing for me on my inverter search, find out the magnum 2012x 2000w with auto transfer switch are garbage i guess. i have a mastervolt chargemaster 12v 50/3 and i just wanted an inverter, just a damn inverter with transfer switch.
everything i want, because i want 2000w plus, are inverter/chargers from brands i think i trust. had old xantrax on this boat, truecharge 40+ charger and a xantrax 400w inverter. boat was sitting for some years, all this equip was from the 90's


so my question is, as i have a victron 3000 sitting in my amazon basket; victron says it has two charging outputs, one main bank, and a trickle chg for the starter battery.
1. is that enough for that purpose? i think it says 4amps.
2. can you run the unit without using the charging capabilities without harm? i see you can turn off inverter but not charger. reason is i would keep current charging with the mastervolt and just use the victron for inverter use.

[mvweebles]

Here is a PSW 2000W inverter with transfer switch, no charger. Mostly for the RV industry, PD makes a respected product. Tech support is good.

https://www.etrailer.com/RV-Inverter...cs/PD64FR.html

Be forewarned, if you do not turn-off your charger, you will back-feed your batteries when on Inverter power. Nothing dangerous, but you will deplete your batteries much faster than anticipated.

Peter

[mitiempo]

Originally Posted by mvweebles

Be forewarned, if you do not turn-off your charger, you will back-feed your batteries when on Inverter power. Nothing dangerous, but you will deplete your batteries much faster than anticipated.

Peter

Could you please explain the above?

[mitiempo]

Originally Posted by Silver_Surfer

so my question is, as i have a victron 3000 sitting in my amazon basket; victron says it has two charging outputs, one main bank, and a trickle chg for the starter battery.
1. is that enough for that purpose? i think it says 4amps.
2. can you run the unit without using the charging capabilities without harm? i see you can turn off inverter but not charger. reason is i would keep current charging with the mastervolt and just use the victron for inverter use.

1. 4 amps is plenty when keeping a start battery charged.

2. Yes you can use the inverter without the charger if desired but why? The Victron Multiplus is one of if not the most flexible charging devices available. Fully adjustable for any battery type including LiFePo4.

[mvweebles]

Originally Posted by mitiempo

Could you please explain the above?

Presumably, the standalone charger turns on when boat is plugged into shore power. If, when shore power is removed the inverter takes over (the transfer switch), inverter will be powering the battery charger which charges the batteries that feed the inverter. An energy loop. There are workarounds (remember to manually turn off charger being one), but if you want auto transfer, a combined charger/inverter is the easiest and simplest.

Peter

[rwidman]

Originally Posted by Anders

750W is the output. The input will be higher, probably ~1200W.

Correct. 750 watts is the cooking power. For the actual power consumption, there will be a label somewhere on the unit (the back or where the power cord is attached) that lists the actual power consumption in watts or amps. This is the figure you need to deal with.

I have a Xantrex 2000 watt inverter with a built in transfer switch. It powers my 900 watt microwave just fine, but the microwave makes a humming sound when on inverter power because it's a "modified sine wave" inverter. A true sine wave inverter would have been a better choice. I bought this many years ago when prices were higher.

BTW: "Xantrex" is not highly recommended, but at the time, this was the only one I could find with a built in transfer switch.

[mitiempo]

Originally Posted by mvweebles

Presumably, the standalone charger turns on when boat is plugged into shore power. If, when shore power is removed the inverter takes over (the transfer switch), inverter will be powering the battery charger which charges the batteries that feed the inverter. An energy loop. There are workarounds (remember to manually turn off charger being one), but if you want auto transfer, a combined charger/inverter is the easiest and simplest.

Peter

With a good inverter/charger there is no reason to have a stand alone charger, and if it is a legacy install, turn off the breaker to it. Keep it for emergency only.

Does remind me of the fellow who used his inverter to power his battery charger thinking he had perpetual power though,