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speedymonk 10-17-2011 08:54 AM

Inverter wiring to panel
I've been thinking about buying a 12volt DC 5,000 watt pure sine wave inverter (AC out) supplied by a deep cycle battery bank to power some of my appliances (two freezers, refrig, furnace (gas) with thermostat and possibly my electric clothes dryer.

I know that some run on regular 110 houshold current and some like the dryer run on 220/240. On my main panel there is no differentiation except some breakers are designed double size (I don't know the exact terms, here).

In short, if I buy a sub-panel and route the wiring of my two freezers, refrig and dryer to them and hook up the inverter, do you see any issues? If the 5,000 watt wouldn't be enough, should I instead get a 7,000 or 8,000 watt inverter (modified sine wave) or just add another pure sine wave inverter with a battery bank. Pretty pricey.? I am concerned about the electronics, specifically the Honeywell IAQ thermostat that is in the furnace circuit.

Should the inverter instead be a 24 volt?

Just trying to figure out what is best here. Any help would be appreciated. There was a smart aleck in another forum who suggested I just hang the clothes out on the line and offered no other help. I'm bagging that site.

Thank you in advance.

a7ecorsair 10-17-2011 08:58 AM

Will these appliance be powered totally by the inverter and NEVER connected to the regular house power?

speedymonk 10-17-2011 09:00 AM

That would be the plan.

gregzoll 10-17-2011 09:36 AM

You would need a whole lot of batteries. 5,000 watts is not much, when you are talking about wanting to power a house for a while, especially if talking only using one battery. You still need a genset to keep the unit charged, due to the drain when first using an appliance will pull quite a bit from the bank. Battery banks are only intended for keeping power up, until the genset is able to take over, which can be anywhere from 10 minutes, to 30 minutes.

This system would work, but costs over $4,000 u.s.

a7ecorsair 10-17-2011 09:36 AM

So this arrangement would be its own system and there wouldn't be a sub panel, it would just be a panel. A dryer operating at 240 volts and 20 amps of current is 4800 watts.

AandPDan 10-17-2011 09:45 AM

Check the ratings on the appliances and the furnace. You won't be able to power everything at once. I don't think 5000 watts will handle your electric dryer alone. If you could, convert it over to gas.

What is the capacity of your batteries? You're looking at drawing more than 420 amps at 5000 watts, not including losses.

speedymonk 10-17-2011 11:50 AM

The battery bank would be two 245 Ah deep cell batteries with a control charger for when the battery levels drop. According to formula that should provide 5,880 watts X.86 efficiency of inverter to give me 5,056 watts of pure sine wave.

Now do I need pure sine wave or could I go to an 8,000 watt system of modified sine wave? What about the electronics of the refrigs and freezers and furnace thermostat or dryer for that matter. I realize everything can't run all at once.

The dryer is 220 and the refrigerator is 110. Any problem with them on the same exclusive panel using ther inverter is my inverter is 12 volt DC in to household out? Would I need 24 volt instead?

I appreciate the responses so far.

gregzoll 10-17-2011 11:57 AM

Two batteries without running 240vac equipment is going to only give you three hours, if you are planning on running 240vac equipment, you are talking maybe getting at the most 45 minutes to 1.5 hours. Again, without a genset, the battery bank is only useful for maintaining 120vac mission critical equipment, until a generator is put in service, within 30 min's. That being a fridge or freezer, networking equipment, dvr, medical equipment.

speedymonk 10-17-2011 12:00 PM

Thank you.

Any info about modified sine wave in this application or using a 24 volt inverter to hook up to the panel? These inverters have the ability to hook up directly or use extention cords for specific appliances.

danpik 10-17-2011 12:17 PM

Is the inverter able to put out 220 volts as needed by the Dryer? The 220 needed is 2 alternating phases of 110 for it to work properly. Also How do you plan to keep the batteries charged? Is this just for emergency purposes such as a power failure?

Marqed97 10-17-2011 12:30 PM

In my experience with inverters, any speed controlled motor, and a lot of other motors, don't always like to start on modified sine. They do run hotter. Electronic timers and clocks run twice as fast. And yes, 245 ah is basically nothing for storage. Most of the systems I helped install for residential use with a trace 4kw sine inverter had 24v banks around 1600 ah minimum. A 5000 watt inverter at 12v is going to pull around what, 500 amps from the batteries peak? Keep in mind you cannot cycle even deep cycle batteries that low. 50% is the lowest SOC I would go if battery lifespan is important.

ptarmigan61 10-17-2011 01:04 PM

There are several questions wrapped up in this one:
1) 12 v vs 24 v. This is a design question, but if you use the same batteries you get the same amount of power. (ie 2 12 v 245 ah batteries will give (12x(2x245)) = 5880wh, or 24x245 = 5880wh. All that really changes is the size of the conductors between batteries and inverter. Higher voltage means smaller wire size.
2) Modified sine wave vs pure sine wave. Different devices respond differently to modified wave inverters. If you use a lot of stuff with electronic controls, you can contact manufacturers to see what they recoomend for their devices. In my experience, you may just have to go with a pure inverter. I have a modifed wave xantrex, and it allows certain things to work (like my portable radio CD player, acts funny with others (my cell phone), and ruins others (portable tool chargers with electronic controls). Oh, one more thing: if you want a single inverter to run 240v, you have to get a 240v inverter.
3) Capacity. This one is all about what you are going to use. If you will use a dryer - or any other rsistance load for that matter - you will have to have a significant battery reserve capacity as well as a fairly large inverter. The only way to figure this one out is to do a whole system load calculation. What do you have in the house, how many watts does it draw, and for how long every day. That will tell you the watt hours you need. Divide that number by 12 (or 24) for the DC voltage. That tells you how much draw you will have on the batteries. Double that number (because you should only draw the batteries down to 50% of capacity). That gives you the battery bank size. Then, go back to your list and look at how much of that stuff will be on at once. That will tell you how many watts capacity your inverter must have.

You haven't said how these batteries will be charged, or what power input to the system will be available. If you had a large solar array, it migh offset some of the problems, but not all. If your solar array is sized to the batteries, I can't see how you could run a dryer let alone all the other myriad household appliances you might have.

For example, I have a Xantrex 2424 inverter (24v input, 2400w AC output at 120v). That gives me 2400 watts of power with a 4000w surge capacity (10 sec). I also have a generator hooked up to it that will charge the battery bank at 70 amps when running, and will take over powering the panel. I have 8 210 ah batteries wired to give me 420 ah capacity at 24 v (=10,080 wh times 50% = 5040 wh available capacity)
We run energy efficient lights, a 24 v Shurflo water pump, a small energy efficient 24v fridge, and have room left over for an Emerson Midawy Eco ceiling fan. I can run a circular saw periodically, and we will be testing a microwave this winter. That may or may not work with the inverter.

speedymonk 10-17-2011 02:24 PM

Thank you for the information. I thought I said that there would be a charge controller hooked up to the inverter that would charge the batteries as they went along.

I appreciate the comments. Thank you.

mpoulton 10-17-2011 02:44 PM


Originally Posted by speedymonk (Post 750639)
Thank you for the information. I thought I said that there would be a charge controller hooked up to the inverter that would charge the batteries as they went along.

I appreciate the comments. Thank you.

Well, that doesn't really answer it though... "A charge controller" could mean a lot of things. Where does it get its power from? Utility? Generator? Solar? What is its maximum charging rate? If it can't supply at least a few kilowatts at all times, then you won't be able to finish drying even a single load of clothes without over-discharging your batteries.

gregzoll 10-17-2011 03:24 PM

mpoulton, me thinks that the OP is trying to achieve Off the grid type living, and without some form of continious power, you hit the nail on the head. Majority that I know, that do off the grid, line dry their clothes either outside, or in their basement. And most also do not use a/c or central heat, but use alternative forms of heating.

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