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Dave King
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In the home battery bank video, Steven says you can make a small to large battery bank. My question is, how large can you make it, say I wanted to be able to run my home water pump which is 220 volt, can I do that with a home battery bank?
kind regards,
davek
 
Troy Rhodes
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Yes you can. But it will be expensive because of the inverter and battery bank size.

If you can determine the starting amps of your pump, I can tell you what you need for an inverter.

If you can tell me how long you want to be independent of the grid for your well, I can size your battery bank.

We would have to know, in minute detail, what the amp or watt draw is for every device you intend to run.





troy
 
Steven Harris
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NO YOU CANNOT RUN YOUR HOME WATER PUMP OFF OF A BATTERY BANK !!! Even if you make a HUGE ONE it will only last a few hours at most. Plus you have the incredible bitch of a job of finding a 240 volt inverter (expensive) to run the water pump !!! Run your water pump off of a GENERATOR. Start the generator, fill a bunch of 55 gallon drums, then use an RV water pump from the barrels to pressurize the house with water. That way, the barrels are your Water battery !! you start the gen, fill them up, turn off the generator.

As far as the video goes, it shows you how to make a battery bank, you can add as many batteries to it as you want, but it'd be a fools errand to try to run a 240 volt well pump from it. Well pumps are rated in KILOWATTS and battery banks run things in watts... your battery bank is not a f'n light saber.

Steve
 
Troy Rhodes
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"NO YOU CANNOT RUN YOUR HOME WATER PUMP OFF OF A BATTERY BANK !!!"

I have seen actual systems that do this. It is not uncommon in off grid situations. It's just expensive. There are ways to optimize the system so that it's not so crazy expensive as well.

My pump runs, on average, about 12 starts a day, and runs for less than two minutes. While the draw IS high (1,100 watts running, almost 4 kw starting) it doesn't run very long. It's a 1.5 hp pump.

My battery bank had 8 t105 batteries, and could supply 1.5 kwh per battery if you go to 100% dod. So the max would be 8 x 1.5 kwh = 12 wkh

Conservatively, I can discharge to 50% DOD, that gives me 6 kw hours.


In 24 hours, the pump uses 1,100 watts x .4 hours = 0.44 kwh


My battery bank could operate my well pump for 6 kwh/.44 kwh = 2 weeks if I ran nothing else and had no means of charging the batteries. Realistically, in a grid down scenario, I'd be careful about water use and get a month out of it, and have a generator to charge the battery bank as needed.


There are also soft start systems that would reduce the strain on a marginal inverter.


There are also 1/2 horsepower deep well 120 volt pumps that make this more do-able as well. They draw ~450 watts running, and ~1,500 watts starting.


I can't run my well pump on my battery bank because the inverter was too danged expensive. As in thousands of dollars. But I'm not optimized for this application.


It is technically possible.


If optimised for this, you can get 4 kw full sine wave inverters for around a thousand bucks.

8 t105 batteries will also run you about a thousand bucks.


I lay out the math just for illustrative purposes. After all the math and the hand waving, Steve is right for all practical purposes unless you're willing to spend a big chunk of cash.




 
Steven Harris
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Troy, I agree with your conclusion. Its just not economically feasible. If you are going off grid then that is a different story, but for a disaster and prep for that, which is what all of my stuff is on, you're just throwing money down the drain (battery bank and inverter) when its far more economical to get a generator and some barrels to hold the water. There is an incredibly larger amount of energy stored in gasoline than there is in a battery bank.

I tend to be black and white. I don't like leaving wiggle room in a conclusion. Yeah.. we could do it, but its not feasible, and I did not want to write a book on the subject.

Steve
 
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