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convert 110v dc to 110v Ac

wbeags

Jan 29, 2022
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I have a number of 56v 5AH batteries that run my electric lawn mower and snow blower. It occurred to me that two of these in series would supply 110 DC. If I could convert this to AC, I could create a backup power supply to run the circulator pumps for my oil burning hot water heating system. This might keep the heat on for a while if we lose power in winter. How difficult is the DC to AC conversion? Are there any obvious problems with this idea?
 

crutschow

May 7, 2021
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How difficult is the DC to AC conversion? Are there any obvious problems with this idea?
The difficulty is creating an AC sinewave, which the pumps may require to avoid overheating.

You need to know the battery capacity and the motor power required to determine how long the batteries can power the pumps.

Might be simpler to just buy a small AC generator.
They aren't that expensive, and would be able to power the pumps (and perhaps some lighting and small appliances) for as long as you need.
If you want to power electronic stuff, you should buy an inverter type generator, which are more efficient, since they can throttle down under light load, and produce a clean sinewave.
 

wbeags

Jan 29, 2022
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Thanks.
Yes, I am looking to install a gas fired generator, but as we don't have piped gas available, it will have to use a propane tank of limited capacity. My thinking was that since I have the batteries, they should be able to provide some additional time. I don't know how much power the furnace control box uses, but there are two pumps which draw 0.7 amps each.
But I get your point that a small gasoline generator dedicated to the heating system could be fueled indefinitely as long as there is a gas station open.
 

Bluejets

Oct 5, 2014
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Solar systems use low voltage (12-36) circulating pumps.
3 m head max. withstand 100 degrees.... Google shows plenty of alternatives.
 

kellys_eye

Jun 25, 2010
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Your pump looks to be around 70-100W which is 'insignificant' in terms of power consumption related to a propane/gasoline generator. I have a couple of 750W inverter-generators (gasoline) that consume under 1 litre per hour at low load (<500W) so a gallon (tank full) will run it for 5+ hours.

If you can get a propane model they consume around 1kg per hour at around 3kW load so a standard 19kg bottle would last 'days' under your load level.
 

Bluejets

Oct 5, 2014
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It would even be feesable to run a dc genset just to charge a battery for perhaps an hour or so.
Then run the negligible current circulating pump via a small inverter for many hours, possibly a full 24 hours.
 

Externet

Aug 24, 2009
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The inverter in my basement works every day fed by 240VDC and yields 240VAC, 6KW (Tesla H6 / Solarcity H6)

Other ----> https://www.ouyad.com/ProductsSolarInverter_164.html

For sure chinese make many flavors... but I do not believe them; this one seems to be an empty box filled with chinese hot air for a price that I will not believe either :

----> https://zripump.en.made-in-china.co...-8kw-Pure-Sine-Wave-Converters-Inverters.html

Other ----> https://solarcube.co.za/product/growatt-5kw-es-high-voltage-inverter/

More ----> https://www.solarbatteriesonline.com.au/product/selectronic-sp-pro-7-5kw-120vdc/
 
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wbeags

Jan 29, 2022
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Jan 29, 2022
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Thanks all, for several good leads on how to survive a multi-day power outage. A whole house propane generator would run out of fuel, but I could run it intermittently while using it to charge batteries that could be used to run the heating system when the generator is off. Alternately, I could get a small gasoline powered generator to power the heating system, replenishing fuel as necessary with runs to the gas station.
 
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