how many kw can you get from auto batteries with grid tie inverter?

[Compensation]

If I charge let's say 1000cca car battery, roughly how many kilowatts AC could you get using a grid tied inverter (Something under 1000w) from a full charge to the inverters shut off point?Its not a grid tie inverter where I found this info, but the one in my truck shuts off at around 10.5-11volts.
Reason being is at 10¢ per kw (rounding down) I was wondering what a full charge would save on the electric bill.

[GAB]

This is an area where my expertise can be written on the back of a small postage stamp with a blunt color crayon. "0"  My guess is that if you did this once a day for a whole year you might save enough to buy a replacement inverter.  Gerald

[Compensation]

Kinda what I am thinking. At 1kw I am thinking a stack of 8 batteries might last 8-12 hours. And at a buck a day there would be no point. Just figured I would ask to see if anyone has experimented with this any.

[Ianab]

And at a buck a day there would be no point.

This ^

CCA doesn't tell us a lot about the battery, just how many amps it will put out for 30sec at 0 degrees C. Useful to know when you are trying to start a truck on a cold day, but doesn't tell you how long the battery will last doing that (not very long)

Amp Hours is the number you need. A 100 a/h battery will theoretically give you 10amps for 10 hours all things being. At 12 volts this is 1200 watt/hours. Accounting for the heat wasted in the cables and inverter, maybe 1 kwh, or 10 cents.

Then running normal auto batteries down to totally flat tends to kill them pretty fast. Deep cycle batteries are built to handle that, but they are heavier and more expensive, but that's what you need to use for a storage system.

Now if you can't get mains power, or it's going to cost a fortune, then that changes the equation. You still have the same amount of power, but it's worth a lot more than 10 cents a unit if you don't have it on tap. But messing about with this and comparing it to mains power costs is pretty depressing.

Most home generating systems use the grid as their storage. Sell power to the grid while the sun shines, draw it back when you need power.

Ian

[Compensation]

Thanks lanab, I didn't get too technical in this but yes I would use deep cycle. I was just referring to a large nice size battery. If you know the technical side then pick a battery any battery.

[Gary_C]

Reason being is at 10¢ per kw (rounding down) I was wondering what a full charge would save on the electric bill.

The real question is what is it going to cost you to get a full charge. If you plan on charging your battery in a vehicle, you will find out quickly that an alternator is not a battery charger. Trying to charge a dead battery will overheat that alternator.

And there is absolutely no efficiency gain with using a relatively inefficient auto engine to add energy to a battery as compared to a high efficiency utility power plant with hear reclaimers, etc. So you are going to lose money, big time.

You can never be more efficient than grid power unless you have a free energy source like solar or wind and even then conversion and storage losses along with equipment purchase and maintenance costs may outweigh any savings.

[Ianab]

True, easy to burn $1 of diesel to make 10c of power....

Ian

[Al_Smith]

Try as one might there is no practical way to beat the power company unless you own a gold mine. Even say if you had access to a fast moving stream for hydro power because in simple terms the money it would cost  could do better in other investments over a period of time .

Well of course you can generate small amounts but other that light a few light bulbs it wouldn't supply much power .

[Compensation]

Free energy, not using a engine. Give me more credit then that  I only work on million dollar CNC's for a living. (Industrial Maintenance)

[tyb525]

Free energy?? Electricity always costs something regardless of where you get it from, and like others have said, it's hard to beat the power company on cost. Especially when it comes to having as much power as you need.

[Fla._Deadheader]

Having been in the Alt. energy business, back in the 70's-80's, let me add a little to the investigation. Our last house, in Arkansas was Alt Energy only. I built my 4KW Wind turbine and tower and erected them myself, with a couple neighbors helping. Traded work for batteries from Train Caboose packs, really deep cycle, and ran stuff directly off a Wisconsin 1 cyl engine, which would saw boards on the table saw or run the planer, while also putting a charge in the batteries. I STILL came out paying the same as the PER KWh rate BUT, NOT the "other fees, which add 40% to your bill. Do the math.

I see most people saying they "only" pay 8-10-12 cents a KWh for their electricity.

IF you figure out the taxes, tarrifs and "other charges", and add them into your "rate", you are paying a lot more than that 8-10-12 Cents per KWh.

When the rates start going up drastically, as they will within another year or so, because of the BIG $$$ people slowly strangling the peons, then, you might wish you had bought in right now, at the cheapest rates Solar panels may ever be. Panels are getting upwards of 17% or more efficiency, and WILL recover some charge into the batteries, even on rainy or cloudy days, just not full charges. Wind blows at night a lot, so a dual system is preferred.

It's not cheap, but, at least you get in before IT hits the fan.

I figure ALL my expenses into the bill down here, and, with mostly hydro power, I still pay nearly 24 cents per KWh. I am starting to build Solar Panels, NOT buy them, and building my Wind Turbine.

IF you have to BUY every system made up for you, and pay all the inspection fees, regulations and "other" fees, it will be tough to come out ahead. That's the way the Govt. is bought off, letting the Enviro wackos have laws passed because the systems don't LOOK good. The old "Not in my back yard " mentality.

Maybe figure out how you are going to get fresh water to drink, because, the water is being mined and sold and a severe drought will be devastating. Down here, in the tropics, we are usually well into the rainy season, by now. However, we are DRY-DRY-DRY. Arenal Lake , which is one major supplier of Electricity in our Northwestern area, is down over 20% capacity.

[Compensation]

For my solar kiln I have 2 panels and 2 boat batteries to run the fan. I have a huge roll of 18ga. Magnetic wire for the coils and fiberglass resin to make the stator. Have some 30 or 35 amp rectifiers so I can start the wind turbine. In my opinion solar and wind compliment each other for best result.

But since we kinda dumped the wagon, caught it on fire and walked off the beaten path right into the swamp. Back to the main question, does anyone have any past experiences with draining batteries right into the grid?   ;D

[Fla._Deadheader]

Volts X Amps = Watts. Do the math. Then, dedict 50% for peukerts effect. What is the battery RATED AT , in AHr ??  Usually it's between 120- 200 Ahr.

CCA means nothing in what you want to achieve. You need to know at what RATE of discharge in minutes. USUALLY , that is 20Min MAX.

So, you have 200A X 12V = 2400Watts divided X.33 (1/3 rd of an hour-20 min)
You get 800 watts for 20 minutes, deduct 50% Peukerts, so you don't ruin the batteries in a very short period of time, and, you get not much help on the electric bill.  You never mentioned how you would charge them or, what the internal draw of the inverter would be, at what % efficiency ??

Yeah, I tend to over ride the question, but, car batteries are useless for any amount of time, other than twisting the crankshaft of the engine.  ;D

[fuzzybear]

with a 4 deep cycle battery bank, not tied to the grid, I run the entire house for 4 days before needing a charge. That runs 4 lights (LED), computer, fan. The lights are on for 16hrs a day in the winter and the computer, fan are on all the time.
   When I added 4-80w solar panels I stretched it out to every 7-10 days I have to charge. This is on 4 hours of sunlight in the winter.  This time of year I run non stop (we are at about 15hrs of sunlight now). If I take the time to adjust the panels I can run a skill saw, chop saw, drill press through out the day, and still not drain the bank. 
   I have power to the property, but it runs to the work shop to run the machinery. I`ve had the solar system for many years of living in the bush, so we just decided to keep using it in the new house rather than running a branch.
   How long a bank will last depends on what you are using it for.  When I logged full time I was lucky to get 12hrs from a single deep cycle battery powering a small radio and one 60w light.  Then LED lights came out and I could get 36-40hrs a charge.
    The best batteries I`ve seen are the fork lift gell batteries. One friend has 3 and charges once a month running entire house and the lights in his shop. He has had them for about 5 years and has yet to have a problem. But they are $$$$.
     Another friend has over $14,000 invested in his solar system, but he runs everything including his auto body shop. He only fires up the generator when he has a lot running at the same time.  He had no choice to spend that much, to get tied to the grid would have cost $250,000.
 
   

[Ianab]

If you are on the grid and want to generate your own power you can, but the batteries become a pointless expense in that situation.

You use the grid as your "battery" and dump any excess power that you are generating into the grid. There is simply no point storing it locally, with all the extra electrical losses entailed with charging batteries.

I guess if a lot of folks started doing it it will make things more complex for the power companies, but they are managing fluctuating loads already, if 5% of their power came from small variable sources they will adjust the power stations to suit.

Ian

[Compensation]

Sorry about the lack of info, I think in my head a lot. I just took a ever ready Maxx and sun force 250 in account for this. Battery is 125ah and sun force is 250 watt. 8batteries=1000ah and 1000ah=12500w just like lanab said and the sun force is 65% average efficiency. So the 12500x .65=8125w. Then 8.125x10¢= jack $#%&. I found the 65% from another persons findings by measuring input and output and that's what I was searching for. Does that sound about right being 65% any other loss I don't see. By the way batteries are just used for transporting the power from one place to another.

So if this is correct you could take about $24 off your monthly bill if you could do this every day. More or less even free energy is more of a hastle then it is worth. At that price by the time the batteries go bad you might have enough to replace them.

For you guys with solar panels can you actually come out ahead if your still tied to the grid with your investment? From what I have learned is, the cost to make sure your usage is less then your solar output would barely break even once the panels start to go bad. Is this true? Wind is nice but i average about 6-7 mph wind.

I also will be looking for a standby generator run by natural gas with the automatic grid disconnect since the power goes out a lot. Sorry this is what happens when I type while I am thinking.

[Al_Smith]

Free energy, not using a engine. Give me more credit then that  I only work on million dollar CNC's for a living. (Industrial Maintenance)

Well that fact and probabley 2-2.50 will buy a beer in most bars in Lima Ohio . Fact is that's exactly what I do plus program robots which has nothing to do with building a static inverter with deep cycle batteries .

Now while it might be a novel idea unless someone lived so far back in the boondocks where the owls romanced the chickens it would be the law of diminishing returns in terms of economics .

First of all you needa  prime mover,a source of motive power .Every time you go from one form of energy such as heat to mechanical power you loose some efficency ,say at least 10 percent .Then you loose another at least 10 percent to convert mechanical to electrical .Then a static inverter is not to most efficient method of changing DC to AC so you loose some more  you loose some more .

[Al_Smith]

---then you try to save it on a battery which really is not that efficient .You are in essence changing forms of energy again .By the time you get done you could be as low as 50 percent of power in to usable power out .

I'm not being pessimistic but more so realistic . ;)

[Compensation]

So really just toss the 65 out the window and stick in 50? Then 50 is the answer.

What CNC's you got? We have Mazaks, toyodas, okumas, doosans, and the rest go down hill from there. Robot's! Wish we had some. I am decent with slk500's but don't know much more then the slicks. What do you use on them? That's one thing I miss is programing.

[Al_Smith]

Oh I really don't have exact figures ,that was a WAG .Inverters are okay for small usage in emergencies .I've seen giant units on computor sytems in refinerys but my heavens they cost a kings ransome .


Now of course if a giant power outage caused the refinery to malfunction it would render the proximity into a waste land so it's a small price to pay in those terms .

The CNC stuff are huge assembley line machines in an automotive engine assembley plant .Cross -Mulher ,Spechet ,Landis ,Toyoda ,several others .Most of them made abroad as seems to be the way of things .ABB robotics ,Lebhaer automated gantrys and a zillion other things I struggle with along with half the engineering staff .

That stuff seems to be on about an 8 year cycle before it's obsolete and the next generation pokes it's ugly head out sending ones knowledge into the stone age .Lordy 46 years at it and sometimes I'm not certain if I'm any smarter now than in the days of latch relays .

[maple flats]

I have a 6.32 KW solar system with 1.48 KW tied to a battery bank and only selling to the grid when there is surplus energy, the remaining 4.84 KW is grid tied only and net metered. I did the total install on the 1st 1.48 KW but had to contract a "certified installer" for the second part and to inspect and certify the part I did in order to tie to the grid. This being said, I only know enough to be dangerous but here goes.
First of all, car batteries are a total waste to store alternative energy. You need a battery designed for that purpose. They are not rated in CCA but rather in AH (amp hours) at a 20 hour or 100 hour rate of discharge. Most common is the 20 hr number. Car batteries are designed to give up a large amount of power in a short period of time, and then immediately be recharged. For alternative energy (solar, wind and sometimes others) the load is steady over a long period of time, often without a recharge for up to 5 days for calculation purposes (I.E. 5 very cloudy, rainy days). Charging these batteries involves large efficiency loses, inverting it involves more losses, (a good grid capable inverter still loses about 3%, some lose double that) My battery backup grid tied inverter was $3400 before I bought the batteries 8 at 240 AH rating were $180 each and charge controller was $580 more, plus heavy wire and incidentals ran another $400. That inverter is only good for 6000 watts. When such batteries are well taken care of ((need weekly maintenance, water levels checked, SG (specific gravity) checked from cell to cell) they might be good for maybe 7 yrs (Mine are Trojan solar batteries, a better is a Rolls Surrette, which cost even more but their top model lasts about 10 years) Then you need to buy the batteries all over again. I would not have batteries at all if I didn't need to heat one room where I have my reverse osmosis equipment for maple, which can not freeze. The 3x5x6' room is insulated with 3" foam, and heated by 3 light bulbs, 100 watts each. One is enough down to about -20 F but I have 3 to handle an ocassional blown bulb.
Study more about the costs before you build or buy a battery based system. It will cost you far more than the grid power you already pay for. Another thing to realize, most areas require a certified installer to make connections that will be "co-generating" with the gird.