On to Inverters...

[jimindenver]

Not all MSW inverters are the same. In fact some are not even MSW, they are square wave. Many things do not like square wave.

We have a Tripp lite 1250fc industrial inverter. It is MSW but has a much cleaner sine wave than many MSW inverters. Their specialty is starting motors and we use ours to take the starting surge of the air conditioner which for a moment is much higher than the 1375w the 900w microwave pulls. It also runs the coffee maker, a 200w heater, a dual burner hotplate as well as charge things up and run the TV/Sat. Those last items didn't like the little inverter we use last year, they ran hot and fuzzy, not now.

In the summer the trailer is as close too all electric as it is going to get. Soon enough I will have electric hot water and refrigeration too, leaving just the furnace on propane.

Remember, You can do a lot with solar as long as you have a lot of solar to do it with.

 

[Reverse Engineer]

I've seen lots of posts from people who say that they recharge power tool with MSW inverters with no problem, and I've seen lots of posts from people who say that MSW inverters FRIED their charger and battery. Apparently, some are ok with it and some aren't.  I've seen the same thing with microwaves.

Regards
John

Yes, you get different opinions and experience with this, I am only telling you my experience.

You can avoid much of the problem though by going "all DC" other than charging your battset from an AC source.

I recently bought a variable DC/DC transformer which will take 12V DC and transform to anywhere up to 24V DC, you just tweak the screw on it. I run the 12V current of the Batt through the transfprmer, it comes out at the 18V my laptop runs on, no inverter necessary! So I can run my laptop direct this way without going through any AC.  Also charge any batt at any voltage from 12-24, so all those 18V power tools, no problem.

Mainly, you just need to be able to keep either 6V or 12V batts charged, and then use all DC appliances.  You can in fact get DC Microwaves.  You can run any compressor for a fridge using a DC motor.  You can run any heating device DC.  All you really need is a DC/AC batt charger system for when you have access to AC, everything else can go straight DC/DC/

 

[Reverse Engineer]

Also, for when you do have access to an A/C outlet, and efficient way to charge is to wire your batts in series and use either a 36V or 48V charger.  You cut your total charging time to 1/3rd or 1/4 this way.

I have many 12V Batts in a variety of sizes because I have quite a few devices that run on them, most particularly the Ewz which takes 3 small deep cycle 12V batts wired in series to run.  I have 3 full battsets for it, 9 batts all together.  I have 3 36V Batt AC/DC Chargers to charge 3 of them together at a time, they pull about 1.8A and it takes about 6 hours to top off 3 batts at a time done this way.

Then I got a few other bigger batts at 12V (car batts, RV Deep Cycle Big Batt etc) also and a charger for them that will crank at around 30A.  You need a good A/C outlet to crank that much though, and usually I charge at much lower rates, around 6A.  That is better for battery life as well.  I can charge the smaller batts off the big ones DC/DC direct, although you need to be careful doing that because you can overload the smaller batt with too much current too fast.  You need a resistor in the circuit and/or monitor the current flow with a meter.

 

[highdesertranger]

my experience with inverters, I have a MSW inverter and I regularly charge my DeWalt 18v cordless batteries off it. I have done this for at least ten years and have not noticed any problems. I would like to get a 12v charger for the job but haven't had the disposable cash to do it. highdesertranger

 

[Reverse Engineer]

my experience with inverters,  I have a MSW inverter and I regularly charge my DeWalt 18v cordless batteries off it.  I have done this for at least ten years and have not noticed any problems.  I would like to get a 12v charger for the job but haven't had the disposable cash to do it.   highdesertranger

You can pick up a transformer from the Chinese that will throughput 10A at variable voltage from 12V to 24V DC for $16.  I have two of them.

 

[akrvbob]

My answers are in red: Here is everything you need to know:

Go buy this inverter: http://amzn.to/1lmxLdL

It's a Xantrex Prowatt  2000 watt pure sine wave inverter and it cost $345 right now. I use it to run my microwave almost daily and I've had it for several years. It's cheap, works extremely well and it's all you need.

Answers to your questions:

1) How do you tell if an inverter is made to get wired directly to batteries? I've had little ones before that plug into vehicle AC outlets. Anything over 100 watts should ideally be wired directly to the battery.

2) Can inverters be powered both by battery and by vehicle? Is this a manual "switchover"? No. Inverters are wired to the battery and the battery is wired to the engine. If you run the engine, the inverter is indirectly wired to the engine. The engine can be on while the inverter is working and the inverter will draw power from it. It's possible to hook jumper cables to an inverter and hook it to the battery. It'll work but it's not a practical idea.

3) If powered by vehicle AC, will I need to run wires to the a) battery, b) alternator or c) AC outlet? No, the inverter is wired to the battery, the battery is wired to the engine. 

4) I want to run a microwave...what do I need to look for? peak wats? volts? I read a review of a 1000v inverter that said "it won't even run a microwave"...how do I process this? Lots of stupid stuff on the internet. Buy the inverter I linked to above and it will run a 750 watt cooking power microwave. Maybe more but that's the size I have so I know for a fact it will run it.

5) If an inverter is powered by vehicle, what limits output...just the inverter, or alternator? for example, could I run a Ecosmart50 instant water heater from vehicle powered inverter, or do large draw appliances introduce limitation beyond just a "big enough" inverter? The inverter draws power from the battery, it can power anything up to 2000 watts or until your batteries drop below about 11.9 volts. If you want to power devices from an engine, you want to buy a generator. Why run a V8 to power a hot water heater when propane will do it much better or a generator if you want an electric one?

oh, and how do I tell if an inverter can be wired to a panel, and not just use the # plugs it comes with? You don't wire inverters directly to panels, you wire them to batteries.

Bob

 

[Reverse Engineer]

Running  2000W Inverter all the time for everything is wasteful of power.  The inverter itself is consuming power to run it.

Most of the time I can get away with just the 200W unit, no fan on it.  Will run my laptop and lights. At least that was how I did it before going all DC.  When I need to make some Ice, I hook up the 1000W unit.  I could run a microwave off that, but I never would.  I don't run the microwave unless I have connection to grid power.  Just reheat the leftovers with propane.

 

[jimindenver]

There are a lot of ways to avoid using a inverter. Everything we used until two years ago was 12v and we were not suffering. That said the range of devices is much larger at 120v and they cost much less too. Believe me a 120v coffee pot works much better than a 12v one. A 12v TV on the other hand looks no different.

One thing to consider is that a inverter big enough to run a microwave is going to take up some space. We had a PowerJack 3000/6000w PSW inverter that cost $200. It was huge. It was fine as long as we just used it for none motor operations. It ran the microwave, coffee pot, hair dryer, hot plate, even a small vacuum but one test of the air conditioner and it wasn't worth the postage to get it fixed.

The Tripp lite is half the size but you would think it had a brick inside. That's because instead of capacitors like the PowerJack has, it has a big transformer. That's what gives it the ability to take the surges. It was a much better $200 choice than the PSW PowerJack was. There are other decent MSW inverters, most cost more than the cheap junk.

One thing to look for is some inverters split the output between the two outlets. So it may say it is a 1500w inverter but each outlet is only good for 750w.

Last thing is if you are setting up, buy the smallest microwave that uses the least watts. A 500w microwave may take a bit longer but everything from the inverter and wiring to the draw on the bank and the ability to charge it back up is smaller too.

 

[Reverse Engineer]

I do not see the need for running a Microwave on such a system.  It's a huge power draw, and mostly unnecessary.

First off, you can mostly reheat anything with propane over a stove top or in a slow cooker done electric, and the power draw there is much less, although it takes longer.  You can combine techniques though to shorten this time.

The deal here is I think that it is a question of trying to make a mobile system perfectly mirror a home system.  I WANT MY MICROWAVE!  Microwaves are huge power hogs, don't use them unless you have a connection to the grid!  Or use somebody else's in a convenience store!  Then they pay for the juice!

Once you dump the microwave and a fridge running full time electric and air conditioning, your total electric needs drop a whole lot.

 

[jimindenver]

Honestly the only reason I didn't replace our high wattage microwave with a smaller one is because I'd rather remove it and put doors on the cabinet. We just don't use it. On the other hand having a system that can handle it means that you can save on propane for cooking. We do the same thing except we use a hot plate instead of the gas stove.

Everyone has different ways of doing things. No one is wrong unless their needs are not being met or they are going to die from ignorance.

 

[Reverse Engineer]

On the other hand having a system that can handle it means that you can save on propane for cooking.

Unless you have a full solar array for charging your battset or are driving around a lot for other reasons, you will spend much more in gas to charge your battery to run your microwave through an inverter which itself will have a 20% power loss in converting the DC ---> AC.  Heating straight off propane is much cheaper, so most of the time you don't save money using a microwave, you lose money.  Unless it is somebody else's microwave on somebody else's electric bill in a convenience store.  Then you can save quite a bit of money.

 

[jimindenver]

Solar isn't expensive like that anymore. A single 200's 24v panels and a 20a MPPT controller and you can use a microwave, tea kettle, coffee pot and more. Cost $4-500. That's what I started with three years ago and it became quite a popular system. Two of mine are on vans now.

The panels that are becoming affordable now are 400w plus. A single panel and you can have a 30a system for around $600. Last year our 30a system would return the bank to float in 30 minutes after a 10 minute run of the microwave.

Bob is right about the kits too. Sellers like Renogy, windynation and Eco-worthy all sell kits that while they are not top of the line, they are more than functional. It doesn't take a degree to slap one of those up on the roof. Use one for a year and you will understand more about solar than you ever will reading Handy Bob.

So again, different strokes for different folks.

 

[ccbreder]

I have a medical necessity for a microwave. I designed my 12 volt system to operate a microwave. Also a toaster and coffee pot, as a bonus. I got a deal on Golf Cart batteries, so have flooded cell. I did much research. The inverter Bob has was very good, but newer versions are getting very bad reviews. They are made by a different company. I decided on a Samlex Power pure sine wave 2000 watt inverter. I wired direct to batteries using 00 agw marine cable. I do have a switch to disconnect from the bank when not using the inverter. I have a ProMariner 40 amp charger for when I can plug into the grid. Only 40 amps so I can use my portable generator. I also ran 6 agw from the alternator to the battery bank. There are no true 12 volt microwaves so the inverter is needed. Every thing else, fans, lights, Indel-B fridge, operate from 12 volt direct. I have a induction cook top, but I'm not sure how that will effect my battery bank. It still takes 10 minutes to boil spaghetti. So I have the propane burner, as well. The future includes solar on the roof.

 

[Reverse Engineer]

Solar isn't expensive like that anymore. A single 200's 24v panels and a 20a MPPT controller and you can use a microwave, tea kettle, coffee pot and more. Cost $4-500. That's what I started with three years ago and it became quite a popular system. Two of mine are on vans now.

The panels that are becoming affordable now are 400w plus. A single panel and you can have a 30a system for around $600. Last year our 30a system would return the bank to float in 30 minutes after a 10 minute run of the microwave.

Cheap solar panels are making it possible to run more electric in the mobile vehicle, no doubt there.  However, both safe deployment of the panels and having a good spot to park to do that are questionable.  You can drop one or maybe 2 panels on the top of a van, but those panels are then subject to a rip off if you park in an urban environment.  In a campground you are probably safe, but in a campground you usually have a hookup to AC power and don't need your own power generation.  You are paying for that with the daily fee to park in that spot.

 

[jimindenver]

It may be just me but in the years I have used solar and discussed it on various forums, I have never once heard of someone getting on a roof to unbolt solar panels.

The portables are easier to steal but I have used them boondocking, in a dry camp ground and here at the house they are left out for testing for days on end.

There is no question that solar or inverters are not for every person in every situation. For those of us lucky enough that they do work it's yahoo baby let the good times roll. Our rig isn't a hard sided tent, it's a cabin on wheels and that's how we use it.

 

[Reverse Engineer]

It may be just me but in the years I have used solar and discussed it on various forums, I have never once heard of someone getting on a roof to unbolt solar panels.

The portables are easier to steal but I have used them boondocking, in a dry camp ground and here at the house they are left out for testing for days on end.

There is no question that solar or inverters are not for every person in every situation. For those of us lucky enough that they do work it's yahoo baby let the good times roll. Our rig isn't a hard sided tent, it's a cabin on wheels and that's how we use it.

I am certainly not against having a good solar set-up to deploy.  I am just pointing out some limitations.  For instance in my own case while living in my Astro Van in NYC, deploying Solar Panels would have been impossible.  As it was, I got the van broken into twice and ripped off. Lost almost everything. If you are working and cannot attend your vehicle all the time, you can get ripped off.  If you are retired and rarely have to leave the vehicle, less chance of that.  If you are a trucker,there are a whole other set of parameters.  Truckers watch out for each other, as I am sure van dwellers do also, but to do it you need to be gathered together in some spot.

 

[BradKW]

So here's something I'm having trouble getting my head around. Let me start by saying what I "think" I know...

1) an inverter/charger can only accept power input from one source at a time, battset, vehicle alternator/battery, or generator.
2) a manual switch is needed to select power source, unless inverter unit is an expensive one with build in logic to do so automatically.

Question: How does a inverter/charger combo know when to charge batteries? If its receiving power FROM the battset, is it also trying to charge them at the same time? If I select vehicle as power source, I assume it will charge battset...but if I were to forget to switch back when engine shut off, do I then drain primary vehicle battery trying to charge battset?

Thanks

 

[Optimistic Paranoid]

Trying to run a converter and an inverter off the same battery is a recipe for disaster, and the fancy combo units are designed so they won't do it..

The vehicle engine's alternator is never hooked through the combo unit.  It doesn't need to be.

The combo unit, with it's automatic switching, uses priority logic.

If there is shore power, neither the generator or inverter will turn on.

If there is no shore power, the inverter will come on automatically unless the generator is running.

Or some variation on the above.  They never try to run air conditioning from the inverter, so if the air conditioner is turned on and there is no shore power, the generator must come on.  And so on.

Regards
John

 

[akrvbob]

Lot's of speculation in this thread. I've been told lots of times I can't run my microwave on solar. I guess I do it by magic!!!!

I love my microwave and wouldn't consider going without it. I also wouldn't consider giving up my 750 watt unit.

400 watts and 4 golf carts will easily run a microwave and you never need to run your engine to power it.

Yes, it draws 1200 amps per hour, that's huge. BUT!!!!!!!!!!! That's only 2 amps per minute, that's nothing when you only run it 5 minutes or less most of the time. I can afford to give up 10 amps out of my 450 ah battery bank.

Running a microwave is no big deal and it will save you money over cooking with propane. It'll never pay for itself, but I have the solar anyway so it didn't cost me any more. I highly recommend it!!
Bob

 

[Reverse Engineer]

Agreed, if you have enough PV panels and a safe spot to deploy them, you can run a microwave off just solar, long as you don't use it too often or for too long at a stretch.

The thing for me on this is that there are FREE available Microwaves all over the place, from grocery stores to convenience store to coffee shops!  There is an Internet Free WiFi Coffee Shop I used to use all the time, heat up some food, chat on the net.  Buy a cup of endless refills Java for $2 and sit there all day.

If I am out fishing, I wouldn't use a microwave to cook.  The fish go in pan with some garlic butter or on the grill.  My RV does have a Microwave, but maybe I used it twice?  If I was more space constrained, I wouldn't have one.

However, everyone is different on this, so if you feel you need a Nuke, power up for it.  Bob's setup sounds pretty good for this.