Inverter and Water Heater

[Al]

Clarification on the smaller 25 Watt inverter. Yes, the cell and Ipad can use the UBS, my electric razor and hearing aid charger not so much.

Al-Ketchikan

 

[Mako]

FWIW we also heat the domestic water via our hydronic Hurricane furnace. We have a large battery bank and 3kw MSW inverter, but removed the generator. With an "aquastat" we can have unlimited hot water without running an engine. It also scavenges engine heat through an exchanger into the hydronic loop.

So you are running a propane gas water heater? Any issues with it?

 

[caltexflanc]

I can't quite make out the labeling, but I don't see the water heater. And other than possibly that one item, I can't imagine what 120VAC item you would NOT want while cruising. And if there were such an item, why it would be unreasonable to simply not use it. Or turn its breaker off. But have no possibility of using it? I don't get that.

All the stuff not powered by the inverter is on other panels. In our case, stove, water heater, AC, laundry dryer, dishwasher, 3 non-inverter battery chargers, and miscellaneous stuff.

 

[caltexflanc]

I guess I am confused now ... what is complicated about putting a matchbox size SSR a few inches downstream of the existing heater breaker? Use two of them (one on each leg) if your heater is 240V. The control power cable (a pair of #18 wires) would be all of about a foot long and connected to the shore power switch.

I think you answered your own question ;o)

You forgot protection for the trigger wire from the shore power.

You can accomplish the OP's mission without adding any new devices or connectors.

 

[refugio]

All the stuff not powered by the inverter is on other panels. In our case, stove, water heater, AC, laundry dryer, dishwasher, 3 non-inverter battery chargers, and miscellaneous stuff.

Ah, now I get it - you have a generator for those away from shore power.

 

[Ski in NC]

I went the simple route. My inverter powers my entire 30A AC panel, so some operator attention is needed. Switch off the big loads like aircon, WH, air comp. Turn off fridge so compressor can bleed down. Switch to inverter, after five min turn on fridge. No relays, but operator has to think a bit.

 

[refugio]

So you are running a propane gas water heater? Any issues with it?

Ah, no - it's a 120VAC Torrid with a heat exchanger loop to the Hurricane with another in-line exchanger to the engine cooling system.

The aquastat calls for heat and - if the hydronic loop is warm enough while cruising - it scavenges from there, otherwise fires the Hurricane.

Semi-related, we have a 400w Insta-hot in the galley. Most quick needs for hot/warm water are handled there and it's only when showering / washing up that the water heater comes into play.

 

[caltexflanc]

No relays, but operator has to think a bit.

We try to reduce requirements for operator thinking as much as possible , given the capacities of the operators in question.

 

[JDCAVE]

All substantial loads on our vessel are non-inverter loads. This included the microwave. When I installed the new magnum 2812, the electrician put the microwave on the inverter side of the panel so we,can do small cooking jobs. I turn the inverter off most of the time unless required. Space heaters in the winter...power off...not a good situation.


Jim
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[refugio]

I turn the inverter off most of the time unless required. Space heaters in the winter...power off...not a good situation.

Well I just turn the inverter off at the dock. Different strokes

 

[caltexflanc]

Well I just turn the inverter off at the dock. Different strokes

No automatic pass through on your inverter?

 

[JDCAVE]

Well I just turn the inverter off at the dock. Different strokes

The manual says it uses 30 watts inverting, no load and 8 watts when inverting and searching. I'm not sure if it is inverting or searching so turn it off when I am at anchor for long periods. The LEDs on the AC receptacles. 30 watts is appx 60 AH over 24 hrs. I'm concerned about the light loads over long periods. They add up.


Jim
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[JDCAVE]

No automatic pass through on your inverter?

I have automatic pass through but would be concerned with draining the batteries with inverter loads draining the batteries in the event of a power failure.


Jim
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[ksanders]

All the stuff not powered by the inverter is on other panels. In our case, stove, water heater, AC, laundry dryer, dishwasher, 3 non-inverter battery chargers, and miscellaneous stuff.

We're the same...

AC stove, electric heaters, trash smasher, water heater come to mind as not wanting to run off of the inverter.

 

[refugio]

I have automatic pass through but would be concerned with draining the batteries with inverter loads draining the batteries in the event of a power failure.

Same here. In practice I generally leave the inverter on thru the summer but go to setting it off in the winter when we use the boat less and I have electric heat turned on.

 

[caltexflanc]

I have automatic pass through but would be concerned with draining the batteries with inverter loads draining the batteries in the event of a power failure.


Jim
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Many inverter systems, and all of the higher end units have an adjustable low voltage cut off setting, so no need to kill your batteries. In my case I set that pretty low, as the sole function of that battery bank was the inverter.

I very much like having the inverter ON in case of a power outage, to keep the refrigerator in particular going. On our set up, we could get fancy if we wanted and have the generator auto start at another predetermined battery voltage (and on newer systems that can be triggered by state of charge as well) and then shut off after some designated period. Don't think we've ever used that on shore power though, it's a bit complicated in that case vs being out on the hook.

 

[JDCAVE]

Many inverter systems, and all of the higher end units have an adjustable low voltage cut off setting, so no need to kill your batteries. In my case I set that pretty low, as the sole function of that battery bank was the inverter.



I very much like having the inverter ON in case of a power outage, to keep the refrigerator in particular going. On our set up, we could get fancy if we wanted and have the generator auto start at another predetermined battery voltage (and on newer systems that can be triggered by state of charge as well) and then shut off after some designated period. Don't think we've ever used that on shore power though, it's a bit complicated in that case vs being out on the hook.

It's okay as my fridge and freezer are DC units so operate without the inverter. My figuring is power outages in the PNW are typically fall-winter events. In the event of a power failure, I don't want the heaters drawing inverter loads as they would drop the batteries down in no time. I'd be checking on the boat if the shore power shutoff. Yes, my inverter has an automatic shutoff setting but it's use is pretty much moot with it manually shut off.


Jim
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[caltexflanc]

OK, I see, in your case you are running the heaters off inverter-connected outlets.

 

[JDCAVE]

Yes and there is no need for inverter based loads when I am away from the boat.


Jim
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[Dswizzler]

Any major trick to installing two different manufacturers invert/chargers so that don't back feed to each other if you want them to charger one bank ? I have combined all my house and engine start batteries in one large bank. Before you say NO I have a separate bank of batteries for my two gensets, in case my 1800 amp hours bank gets low. At this point I have not used my chargers in the past four months because I have been solar power. I am looking to add a second invert so that I can draw more off of my batteries.

 

[JDCAVE]

Any major trick to installing two different manufacturers invert/chargers so that don't back feed to each other if you want them to charger one bank ? I have combined all my house and engine start batteries in one large bank. Before you say NO I have a separate bank of batteries for my two gensets, in case my 1800 amp hours bank gets low. At this point I have not used my chargers in the past four months because I have been solar power. I am looking to add a second invert so that I can draw more off of my batteries.

I would think that sizing is everything. Are your house and starter batteries the same age and type? It's best if they are the same age and type, or you can get into a situation where either good batteries are charging batteries of poorer health, or, overcharging some batteries in order to bring the others up to a state of charge.


Jim
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[ronlord]

Instead of buying another inverter, get a good size charger. Split the bank with a 1-2-Both switch, then you can charge one side with the inverter and one side with the charger. Thats what we do, works good.

 

[Dswizzler]

Not a problem on the batteries they are all1 year old agm lifeline batteries, my concern is the charging circuits back feeding each other. I always turn off the solar before activating the inverter chargers.

 

[MYTraveler]

Instead of buying another inverter, get a good size charger. Split the bank with a 1-2-Both switch, then you can charge one side with the inverter and one side with the charger. Thats what we do, works good.

FWIW, I have both an inverter (which also charges) and a stand-alone charger on my main bank. Normally, there is no need for the stand-alone to be on, but when the bank is deeply discharged, recharging with both brings back the charge faster. If I forget to turn off the second charger, sometimes, when they get down to trickle charging, the inverter and charger will both act up (the charger gets hot but doesn't put out a lot of current, while the inverter signals an error message).

 

[Bay Pelican]

Two good size chargers at one time. I played with this issue and ran into the chargers reducing output. Finally put in an A/B switch between the two battery boxes. Now each charger gives full output to one box. From the meters looks like I am getting a total of 200 amps output. This is acceptable with a 1300 amp hr bank.

 

[FlyWright]

I would think the charger with the higher voltage wins in the tug of war between the competing chargers. The charger with the lower voltage sees the higher voltage as battery voltage and reduces the current. I see this when using my generator/shore charger while running the engines. The Balmar alternator trumps the shore charger with its higher voltage.

 

[MYTraveler]

I would think the charger with the higher voltage wins in the tug of war between the competing chargers. The charger with the lower voltage sees the higher voltage as battery voltage and reduces the current.

That is not my experience. If one charger alone is not able to provide enough current to charge the battery bank at the maximum rate it can permit, then the second charger will see a voltage somewhere between the battery bank's voltage and the other charger's voltage.
But once the batteries are sufficiently charged that their acceptance current (if that is the right term) is lower than what the first charger can provide, the second charger (or at least one of the two) will see that higher voltage and stop charging. I think that is what is happening when my chargers get confused, as I described above.

 

[FlyWright]

I think you're right, MYTraveler. My experience has been with nearly full batts when the peak voltage has been achieved (absorption stage) and the acceptance rate of the charging current is reducing.

In bulk stage charging, both would contribute to boost the voltage.