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Small Cabin Forum / Off-Grid Living / Inverters
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jgiffi
Member
# Posted: 7 Mar 2012 10:51
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I am trying to determine which inverter I am going to purchase and I wanted to get some input from people that have had good/bad experiences with certain brands.

I have a 6500w diesel generator that I would only like to use to charge a battery bank or if I need to run a compressor or power tools. I don't want to get into anything that is going to need too many batteries and eventually I would like to add a solar panel or two(I am in a snow belt and am concerned about generating enough power in the winter from the panels). I plan on using LED lighting to minimize power requirements.

Please provide info on your system and suggestions or recommendations from your experience would be greatly appreciated! Pics are always helpful!

wakeslayer
Member
# Posted: 7 Mar 2012 11:11
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I have found the folks at DonRowe.com to be very helpful. Initially, I bought all my gear from BackWoods Solar in Idaho. When we built our bunkhouse, my power requirements went up a little bit and that is how I found Don Rowe.
I originally had a 600W true sine wave inverter. Really, I have no need for a true sine as I am not running much for electronics. I ended up with a 1750W modified sine wave, and that runs 2 cabins, and 2 other structures without any stress on the system. Mostly just lights, and a mini-fridge for my daughter's insulin in the bunkhouse. (This is what sent me over the 600W)

TomChum
Member
# Posted: 15 Mar 2012 13:06 - Edited by: TomChum
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I am using a MagnaSine MMs 1012. It's 1000w continuous, 1600w peak. I paid about $800 for a re-furb unit from WholesaleSolar but it's about $1000 new. The beauty of this unit is the charger, it's got a 50A smart charger built in, so all I have to do is plug in my generator and it knows exactly what to do. It has a desulfation process too. It has a remote screen on a long wire (using RJ-11 telephone extension wire) that tells what's happening, the amps charging, current battery voltage, etc.

If you don't need true sinewave, then look at the MM1212 (re-furb for $560) this is a beefy unit; 1200W continuous, and 70A charger and all automatic with a remote screen telling you what's happening too. Looks like DonRowe has the same stuff, they might have access to refurbs too.

This is a WILD estimate due to lot of variables -----> but on the 3rd morning, I have to run the generator for about 2 hours to top up. This is not very much. The electricity that I use is not much either, just a laptop, and some LED lights, about 10-16W. Also My generator is a Honda EX1000, which I've seen putting 57A at times into the batteries but is too small for power tools. 6500W is an awful lot of power, you could run a power tool in each hand and more with your feet.

I tried the cheaper inverter/charger route (from Northern Tool) and it 'cost' me $300 in frozen (2 dead, frozen split open) batteries. Northern Tool refunded my $400 but did not pay for my ruined (new) batteries). This beefy Magnum Energy unit, with it's 50A charger is the cat's meow!

My solar system is an 85W panel, with four 125Ah 6v golf cart batteries (at 12v - 250Ah capacity). I have an extra 85W panel that I add for summertime when using an electric refrigerator. Here's other info, about my "battery drawer".

suburbancowboy
Member
# Posted: 15 Mar 2012 13:19
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If you want to experiment get the 1500W invert from Harbor Frieght. Under 200 on sale. This is the route I took and has worked for me for a couple of years but the bearings are starting to go.

razmichael
Member
# Posted: 15 Mar 2012 14:07
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jgiffi, you have not really stated what you want the inverter for: What do you intend to power from it? What can you power from it given limited batteries? How integrated do you want the system to be? Your description of limited batteries implies little or no need for an inverter (or maybe just a small one for the odd minor use of 120V). You may be much better off just getting a good quality smart battery charger that can be used when you run the generator. I'm all for a good inverter when it fits the requirements. I use Xantrex HF1800 inverter which, much like the ones described above includes auto switch over to 120, smart charger, removable control panel etc. I also have a large enough battery pack to use the inverter for more than just charging a phone. This is integrated into the complete system for a mostly 12 volt solution but enough 120 to satisfy my wife when she wants to dry her hair or I want to run some smaller power tools without starting the generator. Your situation sound much less demanding and you may be looking at spending more than you need - not sure.

jgiffi
Member
# Posted: 16 Mar 2012 00:06
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Thanks for the advice fellas, I am more or less looking at a project that may take a year or two to complete (because of funding). I would like to wire the camp for 120v and run the inverter for a ceiling fan, led lights, eventually a well pump and whatever other small odds and ends(coffee maker, etc). I would like something integrated so that when the batteries get low it can switch over to the diesel generator. I would prefer not to run the generator just to run a few lights in the evening (fuel and noise). I haven't done anything with the electrical system yet but I would like to plan on adding a panel or two at some point to keep a charge on the batteries while I am gone without running the generator. I was thinking that 3-4 batteries would be able to handle my needs because I am typically up there for a weekend and I like to spend as much time outside as possible and will probably be working with tools during the day by running the generator. I was looking at the xantrex units because of the good reviews and if I can buy something once that will last and is good quality then I am all about it if it makes sense and will suit what I need to use it for. Raz, how long have you had your xantrex for? Any issues? Easy to connect? Are you running it into a panel? Any pics of your system?

Thanks again for everyone's suggestions

razmichael
Member
# Posted: 16 Mar 2012 07:14
Reply 


Like you I am only planning the cabin! My system is currently in a pop up trailer that simulates our future cabin. I integrated the xantrex into the pop up system in such a way that I can then remove it and use it in the cabin. It is wired into the trailers breakers as well as tied into the 12 volts system. 95% of the time we simply use 12volts and only switch on the inverter when specifically needed. Inverters have an efficiency of 80-90% as well as a small draw on your batteries when idle. I only have some general photos at Photos and these do not include the solar and charger.
If you search the forum on solar, electrical etc you will find lots of threads on the various topics. Also check out some online sites - one often suggested is 12 volt side of life 1 (also a part 2). Although this site is slightly outdated it does have some good advice.

You will find lots of opinions on 12 volts vs 120 and how to wire a cabin. You need to consider wire gauge for the distance needed (for 12 volts as it will suffer a big drop over distance). I think you need to do a clearer assessment on your needs (coffee maker will drain batteries very quickly for example and a well pump could be a big draw) which may help you decide if you want to build a 120 volt cabin with minimal 12 volts or the other way around. This will determine the inverter size, battery bank, panels and the wiring approach. In my case I plan to wire lights, fan, water pump etc as 12 volts throughout and maintain the inverter as a 120 v source when needed through a small panel - and as a charger with the generator on the rare occasions the solar panels cannot keep up with the draw. This has worked well in the pop up scenario and I don't really need to change it - however that is my scenario.

MtnDon
Member
# Posted: 16 Mar 2012 20:26
Reply 


First step is proper planning; an accurate estimate of all the electrical items you want to power. The well pump can be a problem; many are 240 VAC. You can get 120 VAC but many are 240 VAC because of the depth of the pump. Long power lines run into higher voltage drops with 120 VAC. Pumps also last longer and actually will use less power when run on pure sine wave. Motors of all kinds run hotter and less efficiently on square wave (modified sine wave) than on pure sine wave power. There are some great DC pumps from Grundfoss. Pricey though, but ideal for off grid. Pumps also have a surge when starting and therefore any inverter should be able to supply at least 25% more power than the rating on the pump. Much more of there might be other items using power when the pump goes to start. Insufficient inverter (or generator) capacity is hard on both the inverter/generator and the pump motor. No fun having to pull 300 feet of pipe to service the pump.

So an accurate estimate is absolutely essential. There are many online calcs for help in estimating and a link to one in the Useful Links and resources section/board here.


My personal opinion is that DC based systems are only good for the smallest of systems. But that's me.

jgiffi
Member
# Posted: 16 Mar 2012 23:08
Reply 


Sorry I should have clarified sooner that I will have a dug well. Other camps in my area have a well that is roughly 12 ft deep and the water table seems to be fairly high even though I am on a hill because when I was digging the footer for the camp in mid summer my holes were filling with water (4ft). I haven't done alot of research on well pumps but I am hoping that I can find a decent 120v one that doesn't draw alot of current. I plan on having a decent size pressure tank so hopefully the pump won't have to turn on that often. I appreciate all of the suggestions and I will definitely be looking into the well pump more.

Justin

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