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# How many ACV can be pulled from 12v car battery?

#1
05-05-17, 10:40 AM
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How many ACV can be pulled from 12v car battery?

How many AC volts are able to be pulled from one 12v car battery using an inverter or any other device? (Whichever device that can pull the maximum ac volts)

Thank you!

#2
05-05-17, 10:46 AM
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The inverter will convert the 12 volt DC to 120 volts AC.

The size of the inverter will determine how many watts can be drawn.

#3
05-05-17, 11:48 AM
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And when calculating the amps you can roughly figure that the 12 volt amperage will be at least 10 times the 120 volt amperage. So, a 10 amp 120 volt load will pull 100 amps from the battery plus you must account for the inefficiency of the inverter. Some inverters waste 30% of the power so that 10 amp 120 volt load could end up pulling 130 amps from the battery. You can see by the math that inverters are generally appropriate only for smaller loads.

#4
05-05-17, 12:28 PM
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Thank you for the great answers.

Are there anything more efficient or powerful than inverters? A 30% power loss sounds terrible and it sounds like that would kill a battery pretty fast if I have a 700amp battery

#5
05-05-17, 04:22 PM
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Don't expect a battery alone to supply an endless amount of AC voltage. Inverters are often used in automotive situations with the engine running, alternator providing charge to the battery.

#6
05-05-17, 04:34 PM
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Perhaps you should explain what your ultimate goal is. Power your house off batteries? Be able to run some lights in a remote area? Portable power for entertainment setup?

Batteries can supply a huge amount of power, just not for very long. Conversely, they can supply small amounts for a very long time.

#7
05-05-17, 05:48 PM
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I'm trying to wire something up for my house in an attempt to decrease power usage. How long do you think 4 batteries would hold charge while powering an average house before needing recharged?

#8
05-05-17, 06:07 PM
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I'm trying to wire something up for my house in an attempt to decrease power usage. How long do you think 4 batteries would hold charge while powering an average house before needing recharged?
Unless you are using solar panel or some other way of generating electricity at no or low cost, you will not save any money. In fact, you will actually use more power due to losses in charging and inverting.

How long they will last will depend on what size battery you use and what you put on it.
What are you trying to put on them?

#9
05-05-17, 06:53 PM
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Working backwards,
Quick search, Ohio averages 892 kiloWatt hours per month, 30 kWh per day, 1.25 kWh/hour.
1,250 Watts per hour.
Watts = Volts * Amps
At 120 volts ac, thats an average of 10 amps constant for a baseline.
With a perfect inverter, that's 12 volts dc and 100 amps for a baseline.
Four batteries, 25 amps continuous.
Which is conveniently, the load used to determine reserve capacity.
So, the batteries would last, roughly, for the time listed as "reserve capacity".

If you've got a dual rate meter (power cheaper at night), and you want to
charge batteries at night when electric is cheaper, to run during the day,
you're going to need some much bigger batteries.
Like a Tesla...
Hmm, I wonder if anybody has tried to power their house from their Tesla...

edit-

Nissan has
https://www.forbes.com/sites/william...o-power-homes/

https://www.wired.com/2015/05/teslas...ll-power-home/
https://www.tesla.com/powerwall
Well, Tesla makes home batteries, 14kw, so 1/2 day of power is \$7k-\$9k installed.

And Honda does have an electric vehicle to car reverse adapter.
http://www.honda.co.jp/CLARITY/POWER_EXPORTER/

Last edited by Hal_S; 05-05-17 at 07:22 PM.

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