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Small Cabin Forum / Off-Grid Living / making this work to power home
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pabear89
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# Posted: 20 Sep 2018 03:54pm
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New to all this and don't know which way to go.

I have a 6ft water wheel that is set up to turn a 130 amp alt (with space to add another one or 2) that turns 24/7.

Am trying to figure out how to convert this set up to supply the main 100 amp Ac power panel to get away from using the gas powered gen set currently in use.

Its an out of the box idea that has me stumped on how many batteries and converters to use.
Any help would be great.

Thanks

ICC
Member
# Posted: 20 Sep 2018 04:08pm - Edited by: ICC
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So, what you are sayiong is that presently all the AC power used is coming directly from a generator, no batteries there at all right now?

You start by estimating the watt-hours of AC power used in a typical day of use or even better by metering how much is used. Once you know that and what the maximum needed at any one point--- like is there a fridge with a starting surge that may come on when you are using the microwave, then the inverter can be sized and the needed battery capacity calculated.

The 130 amp alternator is for what voltage output, 12, 24---? Is it known for sure that the water wheel is capable of turning the alternator fast enough to generate the full 130 amps? Or two or three alternators worth? Or is that just theory so far?

pabear89
Member
# Posted: 20 Sep 2018 06:06pm
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Yes, power to the main breaker panel is coming from a 40Kw gen head directly.
Have rigged up alt off water wheel and meters 14.5 volts non loaded so far. just playing with seeing if it will turn it at a constant speed. As of now I can vary the wheel speed up and down and have different gear sizes to change alt speeds for correct rpm for output.

Wishing to be able to power the panel for all types of usage, Fridge and micro with ceiling fan and tv ect usage without worry of brown outs.

Yes the 40 Kw head is large, puts out 176 amps on both sides of panel. But you use what you have at the time.

Wind is not constant enough and solar is not reliable as we did small set up when living in trailer while building home.

My idea is to have alt/alts run off water wheel and charge battery bank running inverter/inverters to main panel in home, With gen as back up if needed.

Just trying to wrap my head around what size and how many items would be needed.

Lets say it this way, What do I need to provide 60 amps Ac power so when I'm watching Tv and microwaving popcorn and the fridge decides it wants
to run.
Hope that clears things up. Lol

rockies
Member
# Posted: 20 Sep 2018 06:28pm
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A six foot water wheel? Like one of those old wooden wheels that were installed on mills to grind wheat?

I was watching a show from England called "Victorian Farm" and the hosts have to live in a certain time period for an entire year using only the technology used at that time. One device used was a water wheel. Apparently the power generated by a water wheel is much stronger if the water flows from above into buckets on the wheel rather than having wooden blades pushed by a stream at the bottom.

That said, if you're planning a micro-hydro type installation why not use a modern device to generate electricity?

http://www.backwoodssolar.com/products/microhydro-power

ICC
Member
# Posted: 20 Sep 2018 07:09pm - Edited by: ICC
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Quoting: pabear89
Have rigged up alt off water wheel and meters 14.5 volts non loaded so far.


comments.

The alternator needs to be tested under load to see if the wheel can turn it and produce amperage. Unloaded is meaningless.

It appears to be a 12 volt alternator. It might do a great job charging a 12 volt nominal battery bank. However, if you are looking at a system that could deliver 60 amps at 120 VAC that is very difficult to do on a 12 volt battery system. I'd say, unworkable. I'd say a 48 volt system would be best, maybe a 24 volt battery could suffice, but at the high current draws needed even at 24 volts I would not waste my time on 24 volts. I'd recommend jumping to a 48 volt battery bank and inverter.

A 12 volt alternator cannot charge a 48 volt battery. At least not without getting into a more complicated than necessary DC system that upwardly converts the alternator 12 volts to 48. IMO, that is not wise.

So, I'd say it's back to first base. Determine the average days watt hours worth of energy needed, as well as the peak. It is sometimes best to have a hard look at the appliances, etc that are being used. The common refrigerator as we know it up to now has a very large startup surge. There is a newer technology using what is known as an "inverter compressor" for refrigeration. They do not have a start surge. None. That can help a lot with sizing the power system. Smaller inverter, less battery capacity. Yes, they do cost more, however, use less power.

pabear89
Member
# Posted: 21 Sep 2018 02:14pm - Edited by: pabear89
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Yes its a 6' wooden water well with an overflow setup dumping into the paddles.
Using a turbine would be nice but not what I have at the moment. Plus not sure I have the flow amount required to spin one.
The wheel as set up does spin with steady flow of available water source so working with what I have.

The alt testing I have done so far is to insure it can turn the rpm needed to operate at correct speeds.
As current set up does allow speeds to vary with water flow and the different pully sizing adds to extra rpm if needed. Testing so far I can spin the alt at approx. 3k rpm steady.

Basic Ac working I understand as far as wiring breakers ect. My problem is new to this dc to ac converting stuff.
My brain says if I can produce enough dc amps on a constant level, Tied to batteries as a surge equalizer
to keep things running sort of set up.

Not relying on the battery alone to run things like solar after sun goes down.

Sorry if I am missing something here, Just and old dog trying to learn something new.
Thanks for any and all replies in teaching me.

rockies
Member
# Posted: 21 Sep 2018 06:17pm
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One advantage to a modern micro hydro setup is that the incoming water is channeled into a narrow feeder tube, causing the water flow to increase and "blast" against the turbine blades. Thus, a slow moving stream can be used. Not only do you have to worry about the speed of the water using a traditional water wheel but also the depth (both of which are always changing depending on the weather).

Is this system going to be the primary electrical provider for your home or simply a back-up?

ICC
Member
# Posted: 23 Sep 2018 09:41am - Edited by: ICC
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Quoting: pabear89
My brain says if I can produce enough dc amps on a constant level, Tied to batteries as a surge equalizer
to keep things running sort of set up


Probably correct in theory. But, to get that 60 amps at 120 VAC you need 600 amps at 12 VDC, without taking conversion losses into account. That is a lot of amps which means very large wires if there is much distance to go. I don't have my PC with me so can't run some trial numbers for wire size, but they will be big even to go 10 feet. Cutting down the wire size is one reason higher voltages are used.

FYI 60 amps at 120 volts = 7200 watts.
And 7200 watts is approx. 10 horsepower.

Random thoughts---

So let's say you have a setup that can produce 7200 watts. What happens when you are only using 10 or 20 watts? Unlike solar systems, hydro and wind generators need to use the un-needed power. They use dump loads, usually a water or air heater. That requires a charge controller large enough to handle the maximum watts and amps.



How much water is available? The formula for horsepower from a water wheel is
# of gallons per minute x .000253 x height in feet x efficiency = horsepower

Water wheel efficiency at the axle is something like 80% IIRC. By the time that passes through the gears and conversions DC to AC you might be lucky to have 50%. That's a guess. Rough math shows to produce 7200 watts at 50% efficiency needs about 13,000 gallons per minute with a six ft diameter wheel. That is a good size flow--- 216 gallons per second.


In my life I have found that sometimes trying to use something I already have is more trouble and expense than it is worth. At times there may be some satisfaction in having made it work, but at what cost.

pabear89
Member
# Posted: 1 Oct 2018 02:11pm
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Based on previous electric bills, Monthly usage was 600 plus or minus each month.
So approx. 20 per day usage.

Not sure how this all computes to system size and amount of battery bank required.

Location of home is approx. 120 feet from power source.

I have also pondered installing a various 12v lights and fans in place of standard 120v items.

Watching some tv shows on off grid living and see one that was running a 16 inch planer which I know uses a 220v 30 amp draw to run, How does that work?
Yes there may have been something behind the scene not shown, but I still wonder.

Thanks for the input and thoughts, trying to learn more about how this all works.

ICC
Member
# Posted: 1 Oct 2018 07:45pm
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Quoting: pabear89
Based on previous electric bills, Monthly usage was 600 plus or minus each month.
So approx. 20 per day usage.


Those numbers are KwH I assume. Have you tried to reduce usage, or is that the result of already implementing conservation? LED bulbs everywhere, no incandescent lamps. Modern appliances including fridge, dish and clothes washers. Does that include any A/C? If so how old, what type (window units, central---)


Quoting: pabear89
I have also pondered installing a various 12v lights and fans in place of standard 120v items.


Most people with any experience will say that is a waste of time, effort and makes things more complicated than necessary. If 120 VAC is used for other purposes don't bother with 12 VDC lights, unless the system is quite small. Yours does not sound small.


Quoting: pabear89
running a 16 inch planer which I know uses a 220v 30 amp draw to run, How does that work?


It can be done off grid, without a generator, if the battery bank is big enough. Some inverter mfg like Outback make their 120 VAC output inverters stackable to provide 240 VAC. Others like Schneider make inverters that provide 120/240 VAC from one unit. Some are also able to be combined in parallel to increase available amps. FWIW, I run shop tools that include 240 volt welder, metal turning lathe and a milling machine as well as assorted 120 VAC stationary tools. Mostly the generator does not need to start.


Quoting: pabear89
Location of home is approx. 120 feet from power source.


The power source is the hydro-generator? So then the next question is, where would the battery storage be located and what voltage for the battery bank? Low voltages require larger gauge wires. However, amperage also plays a part in sizing the wires.

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