What is really needed in an inverter?

[Vincentc]

Best I can plan it, on Lilly Marie, an inverter would only run when neither the AC nor the stove is needed. The maximum inverter cycle would be between breakfast and dinner, 10 hours at most with 2 hours generator between.

Powering the refrigerator, chest freezer, coffee maker, stereo, and occasionally the TV DVD seems to be it. Using a "KillaWatt" meter, I measured 50 watts per hr for the 10cf refrig and 40 watts per hr for the 2cf freezer. The coffee maker draws 860 watts during its 5 minute cycle.

Magnum has a 1000 watt pure sine wave inverter/50 amp charger that sells for about $600. 4 6v golfcart batteries would provide about 5500 watts. Looks like enough to me.

Am I missing something?

Regards

 

[Boatsb]

How will it be wired in and what safety and overload protection will you need?

Fyi the coffee will test it. The 1000 watts will probably not be enough.

 

[Pascal]

1000w inverter is a bit small it you re going to use it for a coffee maker or micro wave. Considering the over all costs (batteries, wiring, etc) the extra $ for a larger unit doesn't make a huge difference and it's worth having extra margin

I m not sure how accurate your measurements are for the fridge and freezer, 90w combined sounds low, but over all 4 GC batteries should do the job and last about 8 to 10 hours. I can run my older 20cuft fridge freezer for 18 to 20 hours ( plus some lights, TV etc) with 8 GC batt

 

[MikeP]

1000W won't run a decent-size microwave or a hair dryer. IMO You should have an inverter that allows you to do what you would normally need/want to do during the period concerned without having to say stuff like, "turn off 'X' because I need to use 'Y.'" I'd suggest that 2kw is the minimum size to consider. I suspect you may find things that you want to run on the inverter that maybe at the moment you don't care about. For example, one item we shifted over to the inverter was the Marquipt davit (120VAC). I had not thought about it at all initially but it works far better for us to have it on the inverter circuit rather than having to run the genny to put the dink in/out of the water. Same with the Marquipt Cable Master.

Of course, a lot of this depends on how you use the boat but for us, the limitations of a 1000W inverter would be too much like "camping!"

 

[bobk]

That 50 amp charger will probably turn out to be smaller than you want. Look for 100 amps to minimize recharge time. If your refrigerator is a self defrost, it will pull more power during that cycle and you may have missed it in your test.

Also add a battery combiner into your system so it can charge while you are cruising. Yandina has them at good prices.

Bobk
Chateau de Mer
1981 48MY

 

[magnawake]

Vincent,
I think your on the right track, but most of the time people refer to amp use not watts. First let me say I just installed a Magnum 2800 pure sine in May. The bad things...The tag on the frig label states 1.8 amp (but thats A/C) When you invert to DC its 10 times the amount. I have a remote read out thats shows what I'm using. My frig pulls 18 amps when running on DC. I figured it was running 1/2 of the time. Weeellll, thats when the a/c was running at the dock. When we were at anchor, the ambient temp was much higher and the frig ran almost non stop. Thats the bulk of the usage. Then you have the lights and I ran my laptop with the anchor alarm 100% of the time. In 10 hrs I might have used 200-250 amp hours. Now you need to replace those amps. With a 50 amp charger, that would be 4-5 hrs. However, it will bulk charge (50amps) for several hrs, then step down to say 10 amps. Batteries, 4x6v golf carts, you might be looking at 400-460 total amp hrs. You dont want to go below 50% capacity (to save battery life). You might be on the edge there, but I think your ability to recharge may be lacking with the 50 amp charger. I have 6x 230 amp GC batteries. This gives me 690 total amps for the house. Maybe a little over kill, but most people seem to be happier with 600-900 in the house bank.
Now, more things to think about. This is where it gets fuzy to me, but I'm sure guys here will chime in. You need a inverter with a pass through function where if the inverter bites the dust, you can still operate the refig in the A/C mode. I also have a switch wired in so I can charge my house bank with the engine alternators. That way I dont need to run the genny if I'm traveling that day. Also I highly recommend the remote read out display. Its really nice to be able to see whats going on with the house bank and recharging etc. I spent $2000 to the door for the inverter. It all adds up. Hope this helps.

 

[Vincentc]

Thanks,
Good suggestions.
Considering how seldom we do not use the AC an inverter would have limited use. Primarily to run the refrigeration. Since we only make coffee around meals, I could crank the gen a little sooner.

The 1000w unit has 1200 capacity for 5 minutes and rated for 1600 watts for 30 sec.

Safety is a concern. It appears the magnum has overload protection. I am thinking about putting the batteries port side (she has a stbd list) just fwd of the aft ER bulkhead and mounting the inverter in the closet just aft of the bulkhead. Less than 4 ft between the batteries and the inverter. Assuming 1/0 batt cables and 10 ga for the AC run from the AC panel to the inverter, (approx 6 ft) and one run from the inverter to the galley (about 20 ft) where the refrigerator, stereo, and tv all plug in. One short run from the inverter breaker panel to the wet bar where the freezer is.

 

[MikeP]

If I'm understanding correctly, you do not have an inverter at all at the moment. Assuming that is correct...

I think you will quickly find more things you want the inverter to do once you have one installed. That's why I suggest a 2kw. It's a lot easier to buy/install a 2kw than to buy/install/remove a 1kw and then buy/install a larger one. We had a 1200W in our previous boat (a 36ft Mainship) and it was marginal. We have had the Outback 3232 on the boat since 05 or thereabouts and just last season I added another circuit to the inverter that was not there previously...

 

[sgharford]

Hi Vincent - I put a refurbished Xantrex 2000 Watt pure sine wave in about 3 years ago, combined with 160amp alternators it's the best thing since diesel engines. My 2 bits - get a 3000 Watt inverter with automatic switchover, built in battery charger, and remote display. Larger units run more efficiently then smaller ones and the cost is somewhat negligible when you take into account all the wire and time needed to complete installation. As a side, if you are brewing coffee, cooking bacon in the microwave, and your fridge compressor turns on (LRA)- you will need all 3000 Watts. The large alternator allows you to run everything kinda like a generator when underway - including fridge and TV (the stand by baby sitter for my 3 kids). I use the starboard house batteries to power my inverter - 2 x Rolls 8D's @ 275 amp/hours each. They'll run the fridge thru the night and the TV for about 3 hours when on the hook and still have (just) enough juice to crank over starboard engine. The battery parallel switch to port bank is good insurance in case TV was on too long too. It's a big project, you're going to be running and crimping 0000 size battery wire all over the place so make sure you have a really good crimper.

 

[gbharrington]

Hi Vincent - I put a refurbished Xantrex 2000 Watt pure sine wave in about 3 years ago, combined with 160amp alternators it's the best thing since diesel engines. My 2 bits - get a 3000 Watt inverter with automatic switchover, built in battery charger, and remote display. Larger units run more efficiently then smaller ones and the cost is somewhat negligible when you take into account all the wire and time needed to complete installation. As a side, if you are brewing coffee, cooking bacon in the microwave, and your fridge compressor turns on (LRA)- you will need all 3000 Watts. The large alternator allows you to run everything kinda like a generator when underway - including fridge and TV (the stand by baby sitter for my 3 kids). I use the starboard house batteries to power my inverter - 2 x Rolls 8D's @ 275 amp/hours each. They'll run the fridge thru the night and the TV for about 3 hours when on the hook and still have (just) enough juice to crank over starboard engine. The battery parallel switch to port bank is good insurance in case TV was on too long too. It's a big project, you're going to be running and crimping 0000 size battery wire all over the place so make sure you have a really good crimper.

Scott,
Where did you install. I initially put mine in the original charger location in front of the stbd engine but it didn't like the residual heat after a day of running, so I relocated to the area where the fire bottle is adjacent to the frige.

 

[sgharford]

Hi Greg, I went to opposite side of battery charger on same bulkhead. If looking at that bulkhead as if I were standing at the transom and looking toward bow, I put it in upper right corner with the top very close to the floor boards above as the aftermarket water heater is pretty much right below it. I have not had any problems with it overheating during extended runs and I know you have the same engines. 90% of run time is at 2400 rpm, maybe engines actually cooler at this speed?

 

[MarioG]

We get most of our inverter time in the winter down here in Florida. With that said, the inverter powers:
1. all the A/C lights
2. an outlet in the galley
3. all outlets in the rooms
4. outlet in the heads
5. fridge
6. icemaker
7.aft deck freezer
8. 3 tv's and dvd's/sat tv's
9.aft deck outlet
10. salon outlet

We usually are on inverter during the night when loads are lower. We usually shut down the genny around 9pm or so and start it back up around 9am or so for breakfast during which at that time we are cooking, making water with the watermaker if needed and charging batteries. Usually takes about 8 hrs or so to recharge the batteries back to "float mode". We never have to balance our load useage and with kids aboard that is impossiable anyway. Where we really see the advantage is when we are anchored out for days at a time which equals big savings in fuel.

We use a 3000w Newmar inverter/charger with 4 Rolls batteries on the left bank. The inverter in located in the generator room below the galley. It has been trouble free.

 

[Vincentc]

It does seem like there are more times that I regret making the less expensive choice than times I regret buying more capacity. Looks like the Magnum 2800 PSW / 125 charger would take care of it all.

Regarding wiring, I have 30 amp house service and separate 30 amp box for the A/C. All Magnums are pass through and it appears you can simply connect the inverter the output side of the breaker panel and pass both shore power and generator power.

Am I correct in understanding that I can connect the Inverter AC input after the shorepower/generator rotary switch and pass both shore power and generator output.

On the output side, I assumed if my inverter service was very limited I could just connect the inverter AC output to a 2 breaker panel with one breaker for the refrigerator and galley outlets and one for the freezer outlet in the wet bar.

If I was going to try to do more than that, can I simply go back to the existing panel and somehow avoid having the water heater, stove and battery charger drawing from the inverter, or do I need new breakers and wiring?

I do plan on having an electrician involved, but would like to understand how it should be set up before I get started.

Thanks

 

[OBXTucker]

I'm going through this same process right now....determining what will be powered by the new inverters.
Currently, we're powering the fridge, AC lights, outlets and AC components (nav equipment, monitors, computer) in the pilot house.

Just had a conversation with the yard today about adding the tv's, stereo and sat box (sat itself is wired into the 32/12 inverter).

Is anyone powering their heads or water pumps?

Units will be here Monday and I'm still undecided on how I'm going to wire it up! Honestly, I may combine all 3 banks. I'll end up with a capacity of up to 6400 watts out and should have a ton of amp hours off of the 3 Rolls banks. Generators are available to recharge the banks if I happen to run them down too low.

MikeP, is this essentially what you did? I believe you used a single Outback, but two should work fine, correct?

 

[MikeP]

"MikeP, is this essentially what you did? I believe you used a single Outback, but two should work fine, correct?""

Yes, I combined batt banks and charge the single large bank with the outback. My heads/water pump are 32VDC so in my case, they are always "available" off the batteries but if I had an AC powered pump I'd definitely connect it to the inverter. Two inverters gives you that much more AC capability -obviously the batteries are the limiting factor but you have a LOT of battery capacity. When we run the 3232 overnight, I have never seen the combined oem batt bank drop below 75% of capacity; usually it's around 80%.

I am also a big fan of the pass through - totally automatic configuration for the inverter. It just does whatever it needs to do and you never have to pay any attention at all to it. But if the 30A pass through is a a limitation for the application (it has never been for us) then you would have to set up a manual switchover of some sort. As a pass through, the inverter picks up the associated loads instantly when shore or genny power is lost/turned off. There isn't even a blink from the TV, microwave or any other component that is on the inverter.

 

[OBXTucker]

Thanks Mike.
I'm going the same direction you did. With over 3,000 amp hours available, it should never be a problem.
If I understand it correctly, the Outbacks can also be combined to provide 60A of charging power.

 

[MarioG]

Is anyone powering their heads or water pumps?

Oh yes, I forgot, we also run the AC fresh water pump

 

[Boatsb]

Careful with the inverters pas through mode. It may not pass 30+ amps.

That's one reason I don't like some of the magnums

 

[gbharrington]

The (my) Prosine 2.0 has 30 amp pass through, but that probably varies by manufacturer.

What I haven't seen mentioned here is that the usable (and sensible) battery amp hours is roughly 50% or less of the "rated" amp hours. If you have 690 A/H of battery, you have somewhere around 345 A/H that would be considered usable, particularly if you want to have any kind of battery life. The damage to the battery is not linear to the power draw down, but increases proportionately with the amount of draw down in a given cycle. It's safe to say that it's better to be over "batteried" than under. While you can draw them down lower than 50% (12.2 volts), you end up accelerating their degradation. And if you have batteries that just get the job done when they're new, it's only a matter of time before they no longer have enough capacity.

 

[MikeP]

Absolutely right - the batteries are always the limiting factor; you could stack several Outback (or other brand inverter) and run the entire boat with inverters as far as they are concerned but the batteries might not last for an hour!

As far as the passthrough is concerned, the Outback Mate remote unit will show the amperage being used at any one time for the pass through. I have seen ours at 30 when the charger is running at full power (default for that is 19A @ 120 VAC though it can be set to more or less) and some other reasonably heavy load items are running. If it is running at full charge, you have 11A available for the circuits before the charger will reduce it's output to accommodate the circuit load.

In our use any charging reduction due to circuit loads has made no noticeable difference in battery charge times that we can tell. But if you had some high level, constant circuit load for several hours, I'm sure it would. But nothing that we do/use on the boat for extended periods has that sort of load requirement so the charging amperage is only reduced for a short period if say the microwave or something like that is operating.

The inverter is totally transparent as far as normal boat operation is concerned in our application.