help me choose an inverter!

[chichi]

I need to buy an inverter for my '73 land yacht remodel consisting of solar panels and a backup generator. The things I am looking for are as follows:

Flexible input
highest output within $3k (open to discussion)
ability to plug in to outside power source
ideally has 120AC and 12DC output

I haven't the slightest idea how to choose other than looking up the "best inverter" on google and going from there.

Thank you for your help!

[DaveMc]

Hi Chichi! Almost anyone else on here is far ahead of me in understanding electricity, but in general:

Inverter: takes your 12V batteries and turns it into 110V like a normal plug in a home

Converter: takes 110V and turns it into 12V—this is charging your batteries when you are plugged into “shore power” at home or in a campground.

Generator/solar: both are ways to top off your batteries while camping without hookups.

Check out Steve & Tess/ The More We Explore. He’s done some great videos of solar & inverter install/explanation.

And you can read til your head is swimming by plugging terms into the search bar on the forums. Pay attention to thread dates if you search—I’d avoid anything more than a few years old, as technology changes so fast.

Lastly, know your limitations. I’ve found that a WHOLE LOT MORE gets done if I let a competent shop work on a task instead of DIYing it. What they accomplish in one hour might take me 2-4 hours depending on what it is. Use your time and resources wisely. Good luck!!!

Dave

[alano]

Take a look at the Magnum MSH-M series inverter/chargers. These are high-quality inverters that meet your requirements. These inverters can also use both batteries and an external generator at the same time to provide energy for powering loads that have a high inrush current like air conditioning units.

[chichi]

thanks DaveMc- I should clarify though, i know what all those things are for, I'm just having a hard time choosing.

I too have read a lot about Magnum, thanks alano. but my electrician is skeptical of this brand. i think it is just because he is so star struck by some of the $9k options out there

[DKB_SATX]

Originally Posted by chichi

thanks DaveMc- I should clarify though, i know what all those things are for, I'm just having a hard time choosing.

I too have read a lot about Magnum, thanks alano. but my electrician is skeptical of this brand. i think it is just because he is so star struck by some of the $9k options out there

There's a guy on the forums called Lewster whose business is installing upgraded electrical systems in RVs (solar, high-end battery systems, etc.) and he swears by the Magnum inverter-chargers. Look up his posts on the topic, or contact him for a quote. You might even catch him on his way from the NW to the SE (if he hasn't already gone south) or set something up for the spring if you wanted him to do the work for you.

[uncle_bob]

Hi

Ok, IF you want a device that puts out both 12V and 120V, you can buy such a device. Is that what you are looking for? If you want an inverter, that's a different beast than an inverter / charger combo.

You *might* buy a 6KW inverter. On a full load, it will pull >500A off of your 12V batteries. For reasonable performance (4 hours run time), you would want around 4,000 AH of batteries (if they are lead acid). At $300 for each 100 AH AGM, those batteries would cost you $12,000. The $3,000 on the inverter is pretty minor compared to this.

Step back, take a look at a full system design. Don't just buy this or that bit randomly. There are *lots* of issues to deal with. Max sizing an inverter is rarely a good idea. The bigger they are, the more idle current they likely pull .....

Bob

[chichi]

Originally Posted by uncle_bob

Hi

Ok, IF you want a device that puts out both 12V and 120V, you can buy such a device. Is that what you are looking for? If you want an inverter, that's a different beast than an inverter / charger combo.

You *might* buy a 6KW inverter. On a full load, it will pull >500A off of your 12V batteries. For reasonable performance (4 hours run time), you would want around 4,000 AH of batteries (if they are lead acid). At $300 for each 100 AH AGM, those batteries would cost you $12,000. The $3,000 on the inverter is pretty minor compared to this.

Step back, take a look at a full system design. Don't just buy this or that bit randomly. There are *lots* of issues to deal with. Max sizing an inverter is rarely a good idea. The bigger they are, the more idle current they likely pull .....

Bob

id prefer a full system design. i just have no idea where to start. HELP!

[Al and Missy]

Start with your loads. What do you realistically want to run, and what voltage do they require. Try to use as many 12 volt things as you can to minimize power conversion losses. Get 12 volt televisions if you can find them. Best Buy's Insignia brand has a few, up to about 25", I think. Replace incandescent bulbs with LEDs.

How long do you want to run them without recharging? That will set your battery bank size. How long do you want to take to recharge the bank from solar? That will set your solar array wattage.

I used a spreadsheet to add up the power demands from all my loads.

What loads do you have that need 120 volts. Which ones will run at the same time? Add their wattages and and some margin. That will set your inverter size. Take their current draws and multiply by 12. That will give you their impact on the 12 volt system.


Al

[DaveP]

Chichi,

PM Lewster. He's the man!

[uncle_bob]

Originally Posted by chichi

id prefer a full system design. i just have no idea where to start. HELP!

Hi

Two basic choices:

1) Learn a lot about everything involved. Price out lots of options. Dig into all the details. Spend a year at this. Then go do something.

2) Find somebody who already has been doing this for years. Talk with them about the details you are after. Price out few options. Spend a few months. Than go do something.

There really is no choice three other than (maybe), just turn somebody loose with a blank check and no guidance. That's not one I would recommend

Bob

[pteck]

I get that airstreams are high end. But wow, you would think some of these setups are mission critical applications with the kind of money spent. I'm an elitist in a lot of things I do and have, but in no way would I spend even close to that kind of change on an inverter. That's just me.

Being a system engineer who's professional job is to spec, design, and build real mission critical systems, that balance cost, schedule, and requirements...

I encourage you to focus on use cases first. That means decide what it is that you want to do that you can't do today. Don't focus so much on 4000W this, or all electric fridge that. Sometimes we get caught up in the marketing and more for the sake of more.

Is it the microwave you want to run, or blow dryer? Is a simpler more elegant solution not available? Are you considering the balance of compromises - such as $$$$ money, or 500lb more weight? And with anything your adding, there are the lifecycle costs of complexity to serviceability, maintenance, etc.

Just my 1 cent.

[chichi]

Thank you! No microwave or hairdryer, actually. I don't own those things. No tv either. But I will have a computer (laptop and monitor) running all the time for work. I will have a dometic ac, mini fridge, blender, countertop oven, and led lighting. I will live in full time with the occasional space heater for sleep, but intend to be in warmer climates mostly.

I can't do anything today is the thing. I am starting from scratch. I have no floor, walls, or working door. I want simple and elegant, but i want to live comfortably. I don't need to spend $3k, but thats what i can afford.

I do not know what I am doing. haha! just being honest. I have had an abrupt life change, and since then have spent the last two years getting to here, which is owning an airstream that is gutted with the intent to move in to it full time with my dog. I have lots of hands on remodel experience, but not with the electrical/solar side of things. this is my first mobile experience.

I am leaning towards the advice of lewster and getting a 400W solar panel set up from AM, Lifeline batteries, a Magnum Inverter/Charger, and handy Victron monitor.

Originally Posted by pteck

I get that airstreams are high end. But wow, you would think some of these setups are mission critical applications with the kind of money spent. I'm an elitist in a lot of things I do and have, but in no way would I spend even close to that kind of change on an inverter. That's just me.

Being a system engineer who's professional job is to spec, design, and build real mission critical systems, that balance cost, schedule, and requirements...

I encourage you to focus on use cases first. That means decide what it is that you want to do that you can't do today. Don't focus so much on 4000W this, or all electric fridge that. Sometimes we get caught up in the marketing and more for the sake of more.

Is it the microwave you want to run, or blow dryer? Is a simpler more elegant solution not available? Are you considering the balance of compromises - such as $$$$ money, or 500lb more weight? And with anything your adding, there are the lifecycle costs of complexity to serviceability, maintenance, etc.

Just my 1 cent.

[TheGreatleys]

I have a Magnum 2000 inverter charger. It's a very nice device. It will power anything in my Airstream including the Coleman Mach 8 Cub AC (briefly). I mostly use it to power the coffee grinder.

Think real hard about what you really need the inverter for. You will not be running the air conditioner on battery power. Your solar just won't keep up. A DC compressor fridge is a much better choice than a 120v mini fridge for full timing. LED lighting will be on 12V. You should be able to buy a 12v power supply for your laptop.

That leaves your blender and your countertop oven. Devices with a heating element like an oven or space heater pull a TON of power. Have you considered a propane appliance?

I guess my point is, I thought I needed a big honkin' inverter, but what I really needed was something to power the coffee grinder and the blender, and maybe charge the vacuum from time to time. A 1,000 watt inverter and a good converter charger would meet all those needs at a much lower price point.

I'll make use of my big inverter when I do my battery upgrade so I can run the dishwasher off-grid, but that's sort of beside the point. Run what you can on 12V, and you probably won't need as much inverter as you envision.

[chichi]

Thank you! so how do you power your AC? I will be using LED. I have a few other things that require power- the Precision temp 550 hot water heater, water pump, Nature's Head toilet, and thats about all i can come up with. I will research the DC fridge. the mini fridge draw wasn't too high, but may be worth the switch.

As for the oven, I won't use it but once in a while, but I do want to be able to bake bread and make toast here and there. I only use mine now maybe twice a month. Blender I use daily for about 5 minutes.

Thanks for the tips, I have lots to consider, I just keep getting mixed info. I have to get this project done by June, and I need to move on soon!

[TheGreatleys]

Originally Posted by chichi

Thank you! so how do you power your AC? I will be using LED. I have a few other things that require power- the Precision temp 550 hot water heater, water pump, Nature's Head toilet, and thats about all i can come up with. I will research the DC fridge. the mini fridge draw wasn't too high, but may be worth the switch.

As for the oven, I won't use it but once in a while, but I do want to be able to bake bread and make toast here and there. I only use mine now maybe twice a month. Blender I use daily for about 5 minutes.

Thanks for the tips, I have lots to consider, I just keep getting mixed info. I have to get this project done by June, and I need to move on soon!

Air conditioner runs on shore power. You could also use a generator, but I don't own one. Mostly we change locations to chase better weather if it gets too hot.

The precisiontemp 550, water pump, and NH toilet all use 12V power straight from the batteries. No inverter necessary to run those devices.

If you're using the precisiontemp water heater, that means you have propane which could be used to fuel an RV range. We use ours every day.

You can also use a propane fridge. Ours works well, but I would seriously consider a 12v compressor fridge if I had to do it again. A 120V fridge will require you to run the inverter nonstop, which creates a big phantom power draw. Not a big deal for a few minutes or hours each day, but a nonstop draw adds up quickly if you're depending on solar to keep your batteries charged. I'd plan on only running the inverter when you need it to power something.

[trumpetguy]

Magnum 3000 watt hybrid. I have one and love it.

[J. Morgan]

Originally Posted by chichi

Thank you! No microwave or hairdryer, actually. I don't own those things. No tv either. But I will have a computer (laptop and monitor) running all the time for work. I will have a dometic ac, mini fridge, blender, countertop oven, and led lighting. I will live in full time with the occasional space heater for sleep, but intend to be in warmer climates mostly.



I can't do anything today is the thing. I am starting from scratch. I have no floor, walls, or working door. I want simple and elegant, but i want to live comfortably. I don't need to spend $3k, but thats what i can afford.



I do not know what I am doing. haha! just being honest. I have had an abrupt life change, and since then have spent the last two years getting to here, which is owning an airstream that is gutted with the intent to move in to it full time with my dog. I have lots of hands on remodel experience, but not with the electrical/solar side of things. this is my first mobile experience.



I am leaning towards the advice of lewster and getting a 400W solar panel set up from AM, Lifeline batteries, a Magnum Inverter/Charger, and handy Victron monitor.

I have been using a brand name modified sine wave inverter (that is way too big) and two group 27 flooded cell deep cycle batteries for four years now.

I have less than a thousand dollars in this setup.

I have essentially no 12 volt accessories in my trailer, including a 120 volt 10 cuft refrigerator.

My batteries will last about 20 hours in normal use, and about eight hours if the furnace needs to run all night.

I charge my batteries with a hundred dollar Iota smart charger.

I have purchased a 2,000 watt pure sine wave inverter that I will be installing in my next remodeling excursion. (Less than $1,000).

I priced the Magnum stuff, and while I wanted a Magnum solution, I couldn’t justify the cost.

[uncle_bob]

Hi

Ok, let's talk about the air conditioner. Run current will depend a bit on this and that. Let's guess that it's around 15A. 15A at 120V gets you right at 1800W. That sounds fine for an inverter. With a conventional AC, starting surge will be around 3X running. That's not so fine for an inverter.

15A at 120 will be 150A at 12V with 100% efficiency. AC runs a lot in hot weather in a normal Airstream. A four or six hour "on" time is not at all uncommon over 12 hours. That's 900 AH off of your batteries. Toss in another 400 AH over night. Those aren't maximums, they are pretty typical numbers.

At this point you are up around 1300 AH in a 24 hour period just for the AC at 100% efficiency. Take that to 80% and you are at 2250 AH. You are in the "lots of money" category for batteries.

You still need a way to get power back into the batteries. Coming up with 30 KWH of solar in a day is a very significant requirement. Doing that in any sort of shade or on a cloudy day ... wow !!! Also - the AC numbers above sort of assume some shade / clouds. Lots of sun may not be your friend ...

Yes, it does depend on exactly what the outside and inside conditions are. If 85 outside and 80 inside is "running AC" that's different than 105 in the sun / 95 on the thermometer and 75 inside (if you can even get there). If two hours of AC a day works for you, that also is a bit different.

Indeed, picking the inverter first is fine. If this *is* something you could afford to spend $40,000 on, that's a place to start. The question is - can you afford to spend that kind of money on solar / batteries / installation / wiring / control gear / other stuff to make it all happen? Are you willing to take up the space in and on the trailer that this will require? Will it cost $X? Who knows until the details are worked out. It's not going to be cheap ....

Bob

Bob

[mikextr]

This is what I will be using in my 1967 Overlander:

Inteli-Power 4500 Series 90 Amp All-In-One AC/DC Distribution Panel and Inteli-Power Converter/Charger


Very cost effective when you consider that you are getting the battery charger/converter, upgrading to 50amp service, and getting a new AC and DC distribution panel. The AC breakers are not included so that will add to the cost of this unit.

[alano]

Originally Posted by chichi

I am leaning towards the advice of lewster and getting a 400W solar panel set up from AM, Lifeline batteries, a Magnum Inverter/Charger, and handy Victron monitor.

Excellent choice, even better if you can get Lewster to install it!