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Old 12-14-2020, 06:26 PM   #1
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Default Power inverter question

Good morning, I am looking to put an inverter on my 2800 SCR and am curious what is the typical Watts that people are installing?

Thanks Mike
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Old 12-15-2020, 01:00 PM   #2
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I found this in the forums, using a 2000 watt unit:

https://www.maxumownersclub.com/foru...tall-7859.html
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Old 12-15-2020, 01:06 PM   #3
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It should be sized based on the load you plan to put on it. Add up the power of all the load items then add 50% for margin.
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Old 12-15-2020, 01:14 PM   #4
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I run a 2000w inverter for my needs. The selection as Mike said is based on what loads you want to power and for how long. Usually, it’s not the overall size of the inverter that is the deciding factor, but how much battery capacity you have to feed the inverter.

Although I chose 2k so I could run some larger loads, the usable power is limited by the 225aH of my house bank.
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Old 12-15-2020, 02:54 PM   #5
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Not all devices show draw in wattage. Sometimes it is shown in Amps.

(amps x voltage) = Watts

TV amp Draw: 3.4amps
Voltage: 12v

(12 x 3.4) = 40.8 watts

Also consider the cost of inverting from 12vDC to 120V AC.

A 120VAC device drawing 3.4amps will actually draw 37.54 amps from the 12vdc battery source.

https://www.batterystuff.com/kb/tool...-inverter.html

https://www.rapidtables.com/calc/ele...alculator.html

If you can, consider installing 12v devices, if possible to conserve on energy.
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Old 12-16-2020, 07:53 PM   #6
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Thanks for the input! I plan to install a flat screen, run a Keurig single cup coffee maker for a couple cups in the morning, and power the microwave when I need it. Oh and I have a couple different space heaters one is 1500 watts on the highest setting and the other is as little as 450 watts. They wont ever be run at the same time. I do have a Honda 2000i but dont want to rely specifically on that. The setup is what I need to figure out and what my house batteries can handle? Also, I know of many people that have them in the engine compartment, but have heard people on here say never to do that?
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Old 12-17-2020, 01:28 PM   #7
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Mine is mounted inside the cabin, it didn’t have the rating for use in the ER of a gas powered boat.
As far as the heaters go,I’d look to a different option. The battery bank you’d need wouldn’t be practical in a 2800. As an example, one large 8D battery with a 2000w inverter will give you only 30-40 mins of power at the recommended discharge level. At 150lbs each and measuring 10x12x21, having the capacity to run hours would add a substantial amount of weight and space isn’t available on a 2800.

That’s why I decided on the 2k inverter and the 225 Ah bank I installed to run the 120v convenience items intermittently.

Also, charging comes into play. Replacing the amps pulled is a slow process compared to consumption.
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Old 12-17-2020, 01:49 PM   #8
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Sorry to sound ignorant but what is the 225 Ah bank? I know that is a battery bank, but how many batteries are needed? I do not plan to do a lot of winter or foul weather camping but will need the heater from time to time I would guess. Also is my boat equipped to wire to my house outlets, or do I just plug into the inverter with an extension cord? I only bought the boat a few months back so really dont know a lot about this stuff. Only other boat I have owned was a 20ft Stingray, lol
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Old 12-17-2020, 04:59 PM   #9
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You're going to need to run the generator to power space heaters. Get a 15amp male, to 30amp Female (twist lock) to go from the generator to the shower power in. If you have 2 inlets, then you can also get a 30amp to 2x30amp splitter. This will allow you to charge batteries, top off hotwater, and run space heaters. You will need to manually balance load.
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Old 12-17-2020, 05:23 PM   #10
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Yes Shrew, I already got the 12 guage extension cord and the adapter for my gen to shore connect. So I wont be able to run heater off inverter? hmmm...
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Old 12-18-2020, 04:28 PM   #11
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Quote:
Originally Posted by Roc64 View Post
Sorry to sound ignorant but what is the 225 Ah bank? I know that is a battery bank, but how many batteries are needed? I do not plan to do a lot of winter or foul weather camping but will need the heater from time to time I would guess. Also is my boat equipped to wire to my house outlets, or do I just plug into the inverter with an extension cord? I only bought the boat a few months back so really dont know a lot about this stuff. Only other boat I have owned was a 20ft Stingray, lol
Glad you asked. I was referring to the total capacity of the battery bank in amp hours. My house ‘bank’ on the 3000 is a single 8D size battery.
It’s rated at 225 Ah. On my other boat, I use 2 Group 29 size batteries wired in parallel as a house bank. They are 108 Ah each, combined they provide 216.

Both setups deliver about the same capacity, just with different form factors. Space limitations tend to lean towards multiple batteries where with the 3000 I had the room in the ER for just one big one.
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Old 12-18-2020, 04:52 PM   #12
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Gotcha! I may reach out to you again if that is ok?
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Old 12-18-2020, 05:26 PM   #13
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That’s what the forum is for!

Quote:
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So I wont be able to run heater off inverter? hmmm...
It’s not that you can’t design a system that could run heaters, it’s how practical that solution would be to install on a 28’ boat. Converting 12v DC to 120V AC takes consumes a lot of power. As some of the previous posts suggest, read up on how the batteries, inverter and loads relate and you’ll start to see the challenge in both size and cost.

To run a small heater For any useful length of time means that there has to be sufficient battery power stored to supply the inverter.

To run a 1500 watt heater for 1hr require an inverter sized to handle that load or bigger. That translates to 12.5 amps @ 120V AC. When translated to 12V DC, that’s 138 Amps. Even if the inverter was 100% efficient (which they aren’t) that load for 1 hr would need battery capacity of 272 Amp Hours, as you shouldn’t run the battery down below 50%.

To get 272 Ah of battery capacity, you then need to look at what physically will fit in the boat. That’s space to fit at least four standard Group24’s in parallel or at least 3 Group31’s. Which are similar to the size you have already for your engine batteries. That also adds 180lbs of dead weight to the boat. All of that for only 1hr of runtime on a small heater.

Ramp that up to say 4hrs of run time, plus the other ‘smaller’ loads from TV, etc and you’d be hauling around 16-18 of these size batteries and carrying close to 800 extra pounds. (Think of the difference in performance if you added 4 extra people onboard every trip)

Lastly, to recharge the batteries after use, it would take a about 36hrs to put back the power that was used (assuming good 10 amp charger(s) are used)

Hopefully this highlights the limitations that apply when considering using a DC to AC inverter to power household appliances. Don’t get me wrong, I love having silent and safe 120V power onboard for convenience items and I wouldn’t go back to not having one. There are just some applications where this option doesn’t quite make sense.

I’d go with your plan to plug it your shore power Into the genny and use it to power these hungry 120V appliances. You would the also have hot water, run the refrigerator, etc.
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Old 12-21-2020, 03:28 PM   #14
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Quote:
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So I wont be able to run heater off inverter? hmmm...
Sure, you can run a heater off of an inverter. The question is.....'for how long'? That question is answered based on the draw of the devices in 120VAC, the cost of inversion, and the capacity in amp hours of the house battery bank.

In all practicality, you won't be able to run it for long. It's doubtful the boat has the carrying capacity or space for the batteries to retain the amp hours required to do so for any useful length of time.
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Old 12-21-2020, 04:32 PM   #15
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You may want to check out a solution that uses the 1lb propane tanks. In terms of energy storage for heat, I think propane is better than lead acid batteries. I’ve used the Coleman catalytic heaters in a tent and on deck under the canvas. They are rated for “indoor” use with some ventilation. There are obvious safety considerations if you are using in a cabin, and I’m not endorsing this solution without some research.

Here is a link to some info on camping units.

https://campaddict.com/indoor-portable-propane-heater/

I’d be nervous about running anything while sleeping, but using it intermittently to warm up the cabin could be an option. Look for one with low oxygen shutoff and always follow mfg instructions for ventilation and safety.


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Old 12-21-2020, 08:54 PM   #16
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Thanks for the idea! I will check it out.
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Old 01-23-2021, 01:24 PM   #17
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Default how many batteries SCR3000

i have just purchased a Maxum 3000 and trying to get up to speed, I was surprised to see only 2 batteries but yet I have two switches, can anyone shed some light on this... is two batteries normal... has anyone got better set up and pictures if possible... I was thinking about setting up starting batteries and house batteries....
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Old 01-24-2021, 01:49 PM   #18
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The two battery setup was standard from the factory. 1 per engine with the house load shared by one of them. This was a place where I feel Maxum pinched pennies. Also, Do yourself a favor and draw up a diagram of how yours is wired. Follow the main wires from the batteries into the back of the two switches. Originally, mine was a bit wonky from what I recall.
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Old 01-25-2021, 04:49 AM   #19
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My 3100se also has only two batteries, two battery switches wired one for each engine and house loads seem to be split. Has not been a problem so far so I haven't been motivated to change it.
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