my usage

[livecheap]

I looked at my elec bills and i use an average of16 to 26 kilo watt hrs a day but in july and aug its 50kwh day average for the 2 months september total was 684 kwh and oct was 523 kwh. Now 11 cents per kwh  and just went up 10% so my next bill will be around 12 cents. can a 6\1 handle this load with a 5kw or would you go to a larger unit with less load ? any recomendations would be appreceated. and the cd i hear about does it talk about inverters and batteries v\s direct connection ?  thanks again all .  Sam C.   PS no well pump - propane heat - biggest thing is dryer and stove there elec

[rmchambers]

Hey Livecheap,
    It's going to be tough to know exactly how much power the stove and or the A/C draws because they are 220 and not pluggable into a kill-a-watt device which can tell you exactly how much power you draw.

If you have one of the clamp on ammeters you might be able to open up the breaker panel and clamp around the hot legs of the devices while they are running and see what you get.

I don't think a 5kw genset is going to run the oven and depending on the size of your house and therefore the size of your A/C compressor it may not be too happy with that either.

I'm in the same boat as you regarding electric range (no gas in the street) and having an A/C for the summer heat.  If you're going totally off-grid you may want to size up the generating equipment or re-evaluate your use of them.

Robert

[MeanListerGreen]

You can get various sized propane tanks to run a stove, even if  you live in the city, and you will save money with propane versus/elect. As for the AC you can get a Soft Start kit for the motor so it's easier on the genny.  I would go with a 7 KW gen head.

[livecheap]

my house is only 600 sq ft propane is 3.10 a gallon in ct and elect is 12 cents a kwh  im getting a discount on the propane for now but that could end any time so im trying to go totaly elec and use the propane for emergency use only.do i need a twin cyl or will a single work? just want a little input from you guys till i get a kill o watt and i know for sure.  sam

[Technonut]

You need to scrap the electric stove and go with propane. I just did the same thing. It was difficult giving a nice electric stove/convection oven to my mother, and replace it with a propane unit, but it was necessary to meet my goals. I also got rid of my older fridge and washer. They were replaced with the best Energy Star rated units with the lowest KWH available.....

What you want to do can be done, but you are going to need a large engine/generator for power.....

[hotater]

livecheap--

I produce about 15KW/Hr a day with a Listeroid 6-1 with a 5Kw ST head.  I can push that up to 20 a day, but it's a strain at 5700 feet altitude.
I'm burning #2 red diesel and average 3 gallons a day.  It's about $.33 a Kw/hr at the outrageous prices diesel fuel rose to, plus the cost of the engine/generator and quite a bit of maintenance time invested.

In *my* case, 22 miles off grid, the Lister replaces a 35Kw Onan for producing daily power needs except for big tools, well pump and washer/dryer.  So, it's  "livecheap(er)" by Lister power here.   

[Jim_in_Omaha]

my house is only 600 sq ft propane is 3.10 a gallon in ct

Wow...
Our contract price on propane here is $1.40 a gallon.
Jim

[ronmar]

If you have one of the clamp on ammeters you might be able to open up the breaker panel and clamp around the hot legs of the devices while they are running and see what you get.

I just did this a little while ago in reviewing my own needs. 
3KW(sustained load on a 6/1 genset?) is about 12.5 Amps of current at 240 VAC or two 120VAC legs at 12.5A(25A total for both 120volt legs) or some combination of the two.  As an example, my electric oven draws about 10.8A @240VAC on Bake.  The duty cycle will of course drop off dramatically after the oven is up to the set temp, but each time the controller cycles it on, it will pull that much.  That dosn't leave much leftover for any other loads, but it is doable on a 3KW sustained budget.  On my range, a large electric burner on high pulls 8.5A @240VAC. A large and small burner combined pull 14.1A, too much for sustained operations and no reserve for other loads.  How often do you use more than one stove burner? two small ones might work on lower settings for a short duration, but again with little or no reserve.  My little microwave pulls 11A at 120VAC, or nearly half the capacity of one of the 120VAC legs.  At least you don't have to worry about a well pump cycling on and off.  Your freezer or refer are going to pull between 1 and 2 amps @120VAC depending on their age. But since these are automated loads, you need to engineer enough reserve for them or disable them during high generator loads.  My electric dishwasher pulls around 8A @120VAC during the drying cycle

I think you will find that a dryer or water heater are out of the question on 3KW.  My dryer pulls 20.5A @240VAC and I don't think there is any way to reduce that other than configuring it for air-dry only which means long dryer runs.  A typical water heater has elements in the range of 4500 watts, mine pulls 15.9A @240VAC.  There are ways to reduce this load, at the expense of reduced water heating speed/recovery time.

If you absolutely positively have to have a dryer, you will need a single larger generator, or a small efficient average load genset(big enough for A/C, entertainment and lights) and a larger peak load genset(greater than the 5KW that the dryer requires by itself) that only runs on laundry day(and at dinner time to run the stove and oven and A/C at the same time:).  As mentioned the dryer and stove could be swapped over to gas, removeing these loads from the genset.  You could also possibly look into using the waste heat from the engine cooling system and exhaust of the smaller average load genset to warm the air for the dryer or to heat the water in the hot water tank(cogeneration).  This of course would require the heavy modification of the dryer and some plumbing and controller skills as well as a greater capital investment in the heat exchangers to reclaim the waste heat.  But you payed for the fuel, might as well get all the use out of those BTU's that you can.   Batteries/inverters are another option to store energy at off peak times to help power the peak loads.  the use of batteries, means conversions.  At the least, DC back into AC but most likley generated AC into DC to charge the batteries.  Conversions are always less than 100% efficient, sometimes significantly:(.  The batteries and inverter capable of running your peak loads would also mean another significant capital investment.

Good Luck.

[hotater]

livecheap---

The figures that's left out of these equations are 'surge loads' and what happens to the WHOLE system if capacity is exceeded.
I  *can* run a vacuum cleaner along with everything else, but smoke soon comes from the computer power supply and any UPS in the circuit.
  I can hear the change in engine tone when the freezer kicks on.  That freezer AND and a washer going to 'spin' or vacuum cleaner, or microwave being turned on might stall the engine and break something.

The electric grid can handle about any load you want to start...100 HP irrigation pumps start and run on the grid.  Your generator is *limited* by breakage, not by how much you pay on the electric bill.

GAS refrigeration is a MUST!  I'm running a 1944 Servel fridge, but the electric chest freezer (free to a good home), uses 80% (!!!) of the electricity I'm now generating.   Plan on paying $2000 for a freezer and shipping can be half that again, but in the long run it's WORTH every single penny of it.

GAS cooking is a must.  Period.

GAS hot water is a must.  Bigger period.

AC is an unaffordable luxury. Design for natural cooling in summer and cut the house in half to heat in winter.

Water pumping is expensive electrically...it takes a big generator to run an electric pump. Its' cheaper to pump mechanically with another Lister or Petter type...and MUCH more fun!

I have two generators-- a 6-1 5Kw, and a 15Kw Onan diesel.  The 6-1 takes care of most days all day and into the night.  The Onan is run when I need the lathe, mill, bandsaw, welder, or pump water.  I wash clothes at the same time. I can re-fill the water tanks, do laundry AND do the work I need to do all in about the time I get tired of the roar.
  If you budget your time and your loads right and modify your life around power 'different' from 'normal, you can live well with a 6-1/5kw and a battery bank and inverter to carry the big loads once a week or so.

BTW-- forget ironing clothes, microwaves, electric can openers, toasters, space heaters, hair dryers, curling irons, and other such luxuries.  Most will either smoke the genhead or themselves in short order.

[rmchambers]

I found an interesting page from the city of Ames Iowa.  It lists various devices in the home and how much on average they use as well as how to figure out a $ amount for each.

http://www.city.ames.ia.us/ElectricWeb/energyguy/appliances.htm

I have no financial connection to Ames Iowa, or any other city in Iowa 

Robert

[GeckoPower]

What is the formula for converting 12 volt (100ah) batteries into one kilowatt hour? Then I could find the number of batteries it would take to take care of my usage.  Has anyone tried using AGM batteries for this purpose? Any brand name in particular better than others? Also what kind of lifespan should one expect if only drawing the voltage down 70% (or recommended value)? 

[mobile_bob]

for instance the rolls/surrette top of the line batteries have ~3300 cycles to 50% depth of charge, and probably close to 4500 at 70% DOC

the problem with low depth cycleing and recharging with a genset is the long hours it takes to top the batteries back up

flooded cells can take a much faster charge from 50% to 70% than they can from 70 to 100% where the rate must be tapered back dramatically to keep from
overgassing the cells.

one option is to go ahead and cycle to 50% and then recharge to 70% or so quickly and with low run time on your genset, and then once every 10 days run for longer
hours to top them off and then equalize the cells once a month or so.

you get fewer cycles on the batteries, but in the long run you burn alot less fuel and use up less engine/generator life which usually pays off better than trying to do it the other way.

bob g

[rmchambers]

What is the formula for converting 12 volt (100ah) batteries into one kilowatt hour? Then I could find the number of batteries it would take to take care of my usage.  Has anyone tried using AGM batteries for this purpose? Any brand name in particular better than others? Also what kind of lifespan should one expect if only drawing the voltage down 70% (or recommended value)? 

Couple of things.

Most storage systems use heavy duty 6 volt cells rather than 12 volt and string them together to add up to whatever voltage the inverter needs.  some smaller ones are 12v but more common are 24 and 48 volt systems.

I've never tried AGM batteries, the simpler the better, I have flooded wet cell batteries with water miser caps which trap the vapor/mist coming off the cells and recombine it to a drop of electrolyte and drip it back into the cell.  They are also flip top which makes checking and adding to the cells easier.

I bought my inverter used from a guy up the coast and since I came to pick it up he threw in 4 Trojan T105 batteries which if you check out their web site will tell you all about them.  I have no experience with other manufacturers but I'm very happy with the ones I have.

http://www.trojanbattery.com/Products/ProductSpec.aspx?Name=T-105

Not sure of the maths but this battery will give you 447 mins of 6V @ 25amps so if Watts = Volts * Amps that's 150 watts for 7+ hours 

I have 4 strung together so that would be 600 watts for 7 hours

If I use more power the batteries will provide 115 mins at 75 amps = 450watts for almost 2 hours.  with 4 of them that gets me 1800 watts for almost 2 hours - and so on.  The more you draw the shorter you can draw it for.

my inverter (trace DR 3824) will take whatever you give it DC @24 volts and generate 3800 watts of AC out the back.  Ignoring efficiency loss for a second that works out to be around a 31 amp draw from the batteries which means I'd have less than an hour at max draw. 

You can add capacity fairly easily by adding more batteries.  my next purchase is going to be 4 T125's which can be had for about $140 each - these have a slightly higher capacity which will more than double my total capacity.

Care and feeding of these is pretty simple.  Keep them clean, keep the corrosion away (see keeping them clean) and make sure they have enough electrolyte in them, distilled water being the replenishment)  avoid deep discharge cycles and blast them with an equalize charge once in a while which shakes up the sediment and busts up the sulfated parts of the cells.  My inverter has a selectable equalize mode to do this.

Rather than figure out how many KWH you need to run your house you should figure out how many watts total you consume at any given time.  Using a "kill-a-watt" device to learn the power use of various 110v plug in things is a very good start or check out.

Here's a handy page to give you some estimates of appliances and their requirements

http://www.city.ames.ia.us/ElectricWeb/energyguy/appliances.htm

Using the above values, figure out how many total watts you're going to use at peak times and then you will know (A) what size inverter you need to supply it and for how long and subsequently how much battery supply you need.  (B) what size generator you need to run the house AND recharge the batteries.

There may be some loads you just can't run on batteries OR even the generator unless the gen is huge like the electric dryer or the 3 ton A/C compressor.

One more note before I put you to sleep.  I can't stress conservation enough.  Since I found out that my grid power is going up by 50% starting Jan 1'st I've embarked on a power use detection and reduction assault on my house.  I've replaced almost all my incandescent bulbs with compact fluorescents, changed temperature settings on the thermostat and hot water heater (even though both are oil fired, the less they run the less they use).  Compare microwave draw to toaster oven draw - encourage the use of the lesser of the two and so on.  change the kids room nightlights from the little bulbs to the luminous green lights or LED based nightlights.

Every $ you save due to conservation will be worth way more than that to you in cost avoidance in sizing your system to supply your needs.

My ultimate goal is to put a new roof on the house and then slap some solar panels on it to generate *some* of my daily needs from solar.  The payback will be quite a while but if the price of electricity keeps going up perhaps it won't take all that long after all.

My generation plans are to get a small diesel genset which I can run at least a subset of my house on in the event of a grid failure or when I want to burn up some old engine oil and use the power there to run the house.

sorry you asked? 

Robert

[duh]

livecheap,
For what it's worth, below is a weblink to my off-grid system. Right, wrong or in-between, this has worked very well for me to include surviving a lightning hit about 3 months or so ago. There is a lot of redudancy as well as DC to DC charging, AC to DC, etc, etc.
http://www.diesel-bike.com/System/9Main.htm
Good luck!
duh

[haganes]

the problem with trojan batteries are that they are slow charging.  they were designed for golf carts which are plugged in when not being used.  if you want to minimize generator run time, to need to find an alternative battery.

captain  steven