How many/much do I need?

[Boerman]

I want to make my workshop an "off grid" setup. I now use about 1,100-1,500kwh per month out there. I don't think I ever draw more than 4,000watts at a time but let's say 5,000 just to be sure. I am looking at a 48v wind turbine supplemented with a generator or the grid. Also looking at the golf cart batteries at Sam's. So...how do I determine how many batteries/how much amperage I need?

[wpowokal]

Tell us where you are, so we may help you determine if a wind turbine is practical.

But lets take your figures.....

1500. Kwh/month OK so that's an average of 48Kwh/day.
      
48. volt system so that's 20 Amp x 48 (Kw) = 960 A/h, so that would be at least a 2000 a/h battery system give or take a thousand.
    
    

A source of incoming charge at an average 2 Kw/hour.

A good quality inverter, not one with only electronics in it, to start a 5Kw load so say a 15Kw inverter might do it.

Are you sure your usage is correct?

If so, try just starting with lights off renewable energy.

allan down under

[Boerman]

I live in West Texas. There's no question whether I have enough wind. Around here they have lots of wind farms with turbines as big as a car. The question is whether I have enough money, which I don't. At least not enough for the complete system I want. But I live in the country and we have frequent power outages. Most are fairly short, but sometimes they can be as much as a day and some of the work I do cannot deal with outages. I said it's a workshop, and it is, but some of the work I do is statistical analysis and it is not unusual for a single run to take three days, constant. So my idea is to run off the batteries and use the grid to keep me charged. For now, wind will be a little help but I know it will not come close to supplying my useage.

I will probably purchase a ARI Green Energy 750w turbine to test the waters. Users make claims and dealers make claims. Nobody ever seems to agree on what kind of output you get with a particular turbine, so I will just see for myself. ARI seems to be reasonably priced and I know that they are coming out with a 5KW unit that is already grid-tie in about a year. Until then, I just want to dabble a bit and get a little experience. But my immediate need is to know how many batteries I would need to run 24hr without any grid power.  I have a generator, but it isn't practical to disconnect from the grid and hook it up when you don't know how long a power outage is going to last. Much better, I think, to run off the batteries for a while and see if power comes back on. Then, if it seems to be taking too long, I can disconnect the charger/inverter and hook it up to the gen. No need to ever be without juice.

The charger/inverter I am looking at is the Outback VFX3648. It seems that it will do what I am wanting.

[hamitduk]

It is a cheap china clone, I have it's sister up and flying, what do you want to know?

Hamitduk@yahoo.com

[kurt]

you can do what you want you will just have to decide what are critical loads and have those wired into the inverter if you get the right inverter it will keep your batteries charged and when the grid fails it will automatically switch to battery power just like a very large UPS. then all you need is a transfer switch on the 120v input side of the inverter so you can run the entire thing off your generator without ever loosing power to your work....

[Boerman]

This is the problem when someone who doesn't know something is asking a question of someone who is very familiar with the subject. The knowledgable person assumes that the ignorant dumba$$ knows certain things that are common knowledge to him. (me being the ignorant one). Not to sound like I don't appreciate kurt's answer above. I do. But I know everything kurt stated and have pretty well stated it all, myself. What I don't know is this: if I have lights on, computer on, TV on, heater on, a turkey in the oven(which is also on), refrigerator running and other things running; all totalling 3,000 watts; how much battery storage do I need to keep it all going for 24 hours if the power goes off and I am dumb enough to not turn anything off?? As the ignoramous in this conversation, this seems like a pretty straightforward question to me. But I guess it is not.

I think maybe wpowokal was nudging me in the right direction. But I have 2 trucks, 1 tractor, and a fairly new battery on the kitchen counter. All of them say how many cranking amps they have and how many cold cranking amps they have. But none of them say how many a/h they have.

Maybe I should ask this way: Say I have 4 12v batteries, each with 700 cranking amps, and I hook them all together in series to make a 48v bank. Is that 2,800 cranking amps? And if I plug a 400w shop light to that battery bank, how long will it burn until I need to recharge the bank?

[Airstream]

This has been explained a zillion times. The 12volt Side of Life will easily explain a lot of details while keeping the projects 'man' sized - like in RVs and campers, etc. All valid information that is scalable to larger systems...

Cranking amps are a gimmick that successfully acts to maximize the several times a day you need the high current of a starter motor; then the system essentially runs off the alternator which also charges the battery back.

If a battery is labeled cold cranking amps (CCA) your money is best spent elsewhere -

[sk windpirate]

Hi

Series is

12. Volts        700 Amps
    
24. volts still  700 Amps
    
36. Volts still  700 Amps
    
48. volts still  700 amps
    
    

When Parallel    

12. volts        700 amps
    
12. volts       1400 amps
    
12. volts       2100 amps
    
12. volts       2800 amps
    
    

Hope this helps

[Boerman]

Do you mean the ARI is a china clone? Is the sister the same brand or do they just look alike? How do you like it? Are you satisfied that you got your money's worth?

I didn't mean to imply that either the dealers or the users were dishonest relating to turbines. But it is hard to get a handle on whether the item is a good value for the money. For example: a particular turbine may be "rated" at 400w. What does that mean? Will you get 400w a day? a month? continuous while the wind is blowing? You look closer and the rated windspeed is 26mph. Where does the wind blow 26mph? I live in a pretty windy area and a 50mph wind is not unusual. But when I look on the maps, I see that my average windspeed is just 15mph. So what can I expect to get? Shouldn't these things be rated a little closer to what you can really expect? It just seems to me that all the talk is pretty well meaningless until you get some experience. And it can end up misleading to someone who has little knowledge and experience. So I just thought I might get a small one and see how it compares to what I expected. Again, the ARI gens look to be reasonably priced and the eBay seller has a rating of 100% positive on 575 comments. That looks pretty good. But then again, buyers tend to post their comments when they receive the goods, not six months down the road if the thing breaks down. So if you have any knowledge of problems with their gens, I would appreciate hearing about them.

[electronbaby]

Using Cold Cranking Amps to define battery capacity is like using Wattage to define wind turbine capacity... And like using Horse Power to define how fast your car is... They all mean different things.

There is NO WAY to answer the original question with the info provided. Even if you had all the info, dont expect us to GUESS the end users habits or lifestyle, or elevation, or average ambient temperature, or mean annual wind speed just because he lives in Texas.

If you want to design and implement RE yourself, be very prepared to waste a lot of money and time researching and blowing things up. We all have been there done that. I will be here to help you out when you need it,  FOR FREE.

Answer:

If you have 3000W load running for 24 hours, it will consume 72,000 Watt/hr. If you are running a 48v bank, then you will need a 3000Ah battery bank to be able to discharge to 50%. This is not taking any parasitic losses, resistance losses, or battery losses into account.

[Boerman]

OOPS! Now that you mention it, I did know that. It's just something that I don't deal with often and requires a little more thought on my part. Thanks

[Boerman]

Imagine that, a zillion times and I didn't even see it once. Until now. Thanks for pointing me in the right direction. I imagined that CA and CCA were useless for this application, but that is how all the bats that I have are labeled. Thanks for the help.

[Boerman]

OK, now we're getting somewhere. We are using terms that are familiar to you and you have a more in-depth understanding of what they mean. They may seem familiar to me because I hear them all the time. But I don't really know what they mean. But I'm learning.

Now I see why it is so hard to answer the question. I am looking at a battery bank like a tank of gas. If you have 20gal gas and you get 15mpg, then you get 300 miles to the tank. Or my Ipod. If it is fully charged, I get about 7 hours continuous play. This is sort of what I have been expecting from a bank of batteries. I still suspect that it is similar, just much more complicated. And I don't have all the info I need. I thought I did. The info on the batteries is useless. Ah is gallons. I need to know that and they don't put it on their batteries. But now I see where to find out.

OMG!!! Take a look at this battery. http://www.apexbattery.com/upg-u1-golf-cart-battery-golf-cart-batteries-.html  Am I reading that correct? Is that 35Ah the same as in "you will need a 3000Ah battery bank" above? Or, in other words, would I need 86 of those for the bank I need? I think the wind's gonna have to blow a bit more.

Thanks so much, Roy. No offense to the others who have tried to help, but this has been the most helpful post.

[oztules]

If "I want to make my workshop an "off grid" setup. I now use about 1,100-1,500kwh per month " then thats about 36-50 kwh/day, not the 70 odd kwh that Roy calculated on your 3kw/hr for 24 hrs... so that's some slightly better news???

.........oztules

[electronbaby]

This is true. I guess it depends on which one it is  haha, if he uses 72kwh/day then it would be 2,160kwh/mo.

[TomW]

Berman;

Just for comparison in a real world system, check this out:

http://pics.ww.com/v/TomW/Battery/

or my Diary on the same battery.

http://www.fieldlines.com/story/2009/1/30/161351/147

It is 600 AH at 24 volts. 12 2 volt, 600 AH cells in series.

1100# give or take. I couldn't come close to supplying the kind of load you seem to think you need and that is a fairly substantial battery.

You are right, this RE stuff is a bit of a minefield of terminology and misinformation. Especially if you take internet claims seriously. We all started clueless at some point.

Good luck sorting it out.

Tom

Tom

[wpowokal]

Outback inverters have less surge capability than those built with transformers, it sounds like you need the best surge capability you can get.

You mention some processes that require uninterrupted power, can you divide your shop into critical and non critical circuits. To me this makes much more sense than trying to power the whole shop and getting overwhelmed by the cost.

Then design around the critical circuits, if you have an auto start generator preferably with an automatic voltage regulator (AVR)then many inverters can auto start the genset if an overload occurs and share the load between inverter and batteries, surplus genset capability then charges the batteries.

Many loads take up to 5 time their run current to start them, careful consideration must be given to this point. So you can not have a say 3Kw inverter loaded to 1.5Kw then expect it to start a 1.5 Kw hard to start load ie compressor.

allan down under

[Boerman]

Thanks, Allan, for your help. Yes, I can divide tasks according to their importance and adjust accordingly. The whole point of my questions was to figure out if that was necessary. It would seem foolish to start the project without knowing what the cost will be. I'd be willing to bet that the average person has no idea about the storage capacity of these batteries. Most of us who drive have had to buy a new battery. Those batteries give us the information needed for the purpose intended. You might say that those batteries are sprinter batteries. But for the purpose I am working on, I need a marathon battery; not so much fast but having endurance. Now that I know that, I can better access how I need to proceed.

Your point about surge capacity is well taken. Something I need to consider. Thanks for your help.

[hamitduk]

We will try to answer your questions her:

Yes the ARI is a relabel from China, and so is its sister.

No it is relabel from another company, the control no is a bit diff, no LCD screen.

It works, I got it to better understand what was out there.

Did I get my $$$ worth, if all the remachining I did , was done in china that would have been nice.

Mine was send with a mount that claimed to be good for 1.5" or 2" pipe, not when the id was 1.9" it fit nothing! The Blade after mounting slipped on the shaft.  There are three LEDs on the control box, they had to call China to find out what they were for!

The dealers are dishonest, but for a good reason, they all have the same crap, so they have to make there's sound better. Some list power out at 26MPH, some @ 28MPH, some @ M/S (Meters per Second), a bit confusing.

 The rating is in Kilo-watt-hours, so 400 watts is .400 Kilowatt per Hour, and yes it is while the wind is blowing, and it is never stable, gusts.

You kinda hit the nail on the head, ratings, they can throw numbers at you, but you only get what hits the blade!

Well before you believe there are reasonably priced look here?

http://www.magnet4less.com/index.php?cPath=8_116

EBAY RATING are a crock of Bovine DUKY, you rate some body as great because he sell you something and you get it. They order the parts, get them in stock, they place a sale add on EBAY,  you order it and they hand it to a shipper and you get it! What did this person do that the guy at the fast food joint didn't do?

Inshort, I got it to see what was being sold, and that is what I got. Dose it work, yes, I have not seen more than 400 watts.  I get 0 to 30 MPH here.

If you want to talk My E-mail address was in my opening comment, E-Mail me your number and I will call ya.

Hope that was helpful, my comments/posting normally get deleted.

I also listed the users manual in my photos section.

[wdyasq]

I think the man's first step should be to get a good Watt meter "Kill-A-Watt" or one of the recording types and actually find out what power he is using and what power he needs 'uninterrupted'. With this information he can start giving true information and formulating a plan that is realistic.

In the RE world, it is sometimes cheaper to replace an inefficient appliance or computer than power it with RE. It is always cheaper and easier to conserve than to produce power.

"Rule of Thumb" on RE systems, for normal size thumbs I guess, claim is it is 5 times more expensive to produce power than conserve it.

Good luck,

Ron

[TomW]

duk;

Hope that was helpful, my comments/posting normally get deleted.

That, sir, is a flat out falsehood [spelled lie].

Tom

[Gordy]

Hi Boerman,

That 86 batteries will get you 3000ah at 12 volts. You mentioned earlier about a 48 volt system so 86 x 4 = 344 batteries x $79.95 = $27502.80 + tax and s/h

Earlier it sounded like you don't know the difference between starting batteries and deep cycle. I lost a better link on battery types and performance, but this one will get you started. http://en.wikipedia.org/wiki/Lead-acid_battery Scroll down to applications and or Cycles.

Gordy

[hamitduk]

Tom

A lot of my posting have been deleted, this is a fact, I have E-Mail asking why and have rarely got any answers, see below

"Dan

I posted a request for info on the board, and it was deleted. I wanted to know if Rotors get hot, a simple question, and it is gone. (under wind)

Hami"

unanswered!

When I don't get a answer or removed posting, I stop posting, why waste my time.

Ok Normally was a bit of a over statement maybe 30%?

The only reason I answered this posting is I have direct experience with the unit and he asked.

Then I get called a lier, I don't need this, if I say what I really feel, it will get deleted!

Hami

[kurt]

i picked up a kill-a-watt meter at my local harbor freight store and i told some people on irc and one of the guys there hit there harbor freight looking for one and they had one as well so they seem to be stocking them now i found mine locked up in a display case at the front of the store with the inverters and stuff they are a little over $20 that thing is allot of entertainment when you first get it you want to plug everything into it very educational.....  

[Boerman]

I found a useful utility here http://www.xantrex.com/support/howlong.asp

[wdyasq]

Boerman,

That sort of spreadsheet will get you in a mess. All of those figures are 'generic'. As a couple of examples I'll give my "3-1/4 HP Porter-Cable router" and my 40+ year young #77 Skillsaw.  

The 3-1/4 HP router should be ~2400W. It's maximum draw is closer to 2000W, for less than a second, and it really runs at 700-1000W. My 'Skillsaw' will actually pull over 25A if you load it well ....

Some common refrigerators us as little as a kWh a day while others of similar size use 3 times that amount. The stupid practice of staring at the 24 pack of beers wondering which one to pick with the door open uses more energy than the person who knows how to quickly pick the proper beer and does it.

Do yourself a favor and do your own research and figure out what you need.

Ron

[TomW]

Ron;

I have to agree there. Seems a perfect time to invest in a kill-a-watt meter as mentioned earlier in the thread [I think]. My fridge is not too bad just keeping stuff cool but when it kicks on the auto defrost the amps go the wrong direction. My one horse table saw [old Craftsman direct drive] drags about 3 KW under load ripping and a massive surge on starting. If you called that "about 750 watts" you would be off by a factor of 3 to 9 depending on when you check the draw while using it.

Nameplate ratings seldom seem to accurately reflect power use.

I had one TV that drew 45 watts waiting for the remote to wake it up and ran at like 65 watts. That is crazy. I don't have it anymore but its another example.

Most folks do not have a clue how much "power" a kilowatt hour is.

Research is the best way to know what you need and help you see why "turning it off or leaning it down" helps more than making it yourself.

Just the view from here.

Tom

[Madscientist267]

That's a nice piece of hardware you got there... How much did it runya?

Steve