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I want to calculate some expected power capacity over time for a battery + inverter
Posted by: deckeda
Date: April 02, 2012 07:58PM
I need to run a laptop, 15" lcd monitor and inkjet printer outdoors for at least 2 hours without an AC source. All three things will be on the whole time, not sleeping/dimmed/paused, printer included.

I was told to get a marine (deep cycle) battery and a 500W inverter.

I'd prefer to get two 100ft extension cords instead, but am currently unsure of the distance away from power.

And are some inverters more efficient than others? Wondering if I could get one without a fan and keep it out of direct sun, or if that's worth worrying about.
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Re: I want to calculate some expected power capacity over time for a battery + inverter
Posted by: mattkime
Date: April 02, 2012 08:06PM
you laptop should be fine for two hours. the monitor and printer will be the main concern. it might be a good idea to measure their power usage and perform the necessary calculations.





VTPKL it!
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Re: I want to calculate some expected power capacity over time for a battery + inverter
Date: April 02, 2012 08:30PM
Inverters are most efficient between 30% and 80%. The typical efficiency is about 70%. If you calculate a power use of 60 W (at $16-$18, a Kill-A-Watt is a good way to test), and you want to run them for 2 hours. As a bare minimum you need a ((120 W/0.7)/12 V)= 14 Ah 12 V battery.



in tha 510.
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Re: I want to calculate some expected power capacity over time for a battery + inverter
Posted by: John B.
Date: April 02, 2012 08:39PM
Does it need to be silent? Single-time event? Maybe look at renting a small Honda generator...I see them a lot at street fairs, and while you know they're there, some of the Hondas are amazingly quiet compared to other generators out there.
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Re: I want to calculate some expected power capacity over time for a battery + inverter
Posted by: deckeda
Date: April 02, 2012 09:03PM
A small gennie was my first thought, and yes I've used the small Hondas for other things and they are quiet compared to the typical Briggs and Strattons. But even that is more than I want to deal with. I'm still trying to find out why long extensions wouldn't work.
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Re: I want to calculate some expected power capacity over time for a battery + inverter
Date: April 02, 2012 09:51PM
Two 100' 12 gauge cords should work for the load you have listed. The problem is if you are trying to run a 1200 W heater, and a 600 W portable saw that far away, the voltage drop might be enough that the saw motor is in a continuous brownout situation and will overheat.



in tha 510.
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