Can I run 1 15.000 btu a/c off my house batteries I have 3 12volt house batteries going to a concert and I can run the gen set most of the time but I know they have a shut down time and I need some a/c can you do that? I have a freedom 2000 inverter.
likely not. even *if* the AC is connected to the inverter, and i doubt it is, the draw would be huge and beyond the limits of the 2000-watt inverter. 2000-watts at a nominal 120-volts results in a maximum draw of 16-amps. simple way to test. disconnect from shore power, keep the genny off, power up the inverter and flick on the AC.
73,
rich, n9dko www.bananaboatbytes.com
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2000 Itasca Suncruiser 35U
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Hi,
You would need a much larger battery bank. Right now you have at best 300 amp hours, or about 3,500 watts before the totally full battery becomes so dead it will not start the generator. That is only enough power to run the A/C for about 1 hour before the battery is dead.
Just because you have 300 amp hours at the 20 hour rate does not mean that you will have 200 amp hours if all used up in one hour, and the faster the battery supplies power to the inverter, the lower the voltage drops, so it will take more amps to equal the 1,500 watt output. So to start out with, at 150 amps X 12 volts, you will have a output around 1,500 watts. AS the battery voltage drops below 11 volts, then 170 amps will be required to have the same 1500 watts output.
If you had a solar system capable of putting out 1,500 watts, then I would say yes it is possible, especially with 8 golf cart batteries, and a 3,000 watt pure sine wave inverter. Sine wave is required to run a high torque load such as a air conditioner compressor. I would run them at 24 volts, they would be much more efficient that way. You would have about 450 AH at 24 volts or about 10,000 watts. Then the 12 volt batteries can be used to power the lights, and other 12 volt loads, and not see the lights go dim when the compressor cycles on and off. Also at 24 volts, the 1,500 watt load will only take about 75 amps, so wiring can be smaller, and battery terminals are much less likely to melt at 40 amps than at 75 amps. (each string of 4 batteries will put out around 40 amps, making 80 amps availible to the inverter, so it can put out 1,500 watts. A 48 volt inverter would be even more efficient, Trace makes a nice 5,500 watt unit, it will also work with the generator to load share, and take up part of the load when the generator is smaller than the load being put on it.
rk911 wrote: likely not. even *if* the AC is connected to the inverter, and i doubt it is, the draw would be huge and beyond the limits of the 2000-watt inverter. 2000-watts at a nominal 120-volts results in a maximum draw of 16-amps.
simple way to test. disconnect from shore power, keep the genny off, power up the inverter and flick on the AC.
You will probably damage the A/C, inverter, or if it actually worked for a few minutes melt a battery terminal if you try it. Probably what will happen is the inverter will go into low voltage shut down, or overload shutdown, hopefully before something breaks.
Yes, you can run the air conditioner, but you will reach 50% state of charge on the battery bank quickly.
Based on 150 amps @ 12 volts and assuming 300 amp-hours for the battery bank, in theory, you might get 40 minutes. In real life, due to voltage drop, that number is likely to be closer to 15 minutes.
Oh, Heck, @Captain_Happy, I bet the OP could do it. It'd keep the RV cool for, what, maybe 20 minutes before the three batteries were sucked completely dry, but it's doable. He/She only needs to add about, um, 69 more batteries to get completely through the night.
**For the humor challenged, that's supposed to elicit a chuckle. If it fails to do so, please just let it go.**
So many nay-sayers. There is a lot of work being done in this area and there are many rvers who use solar/battery to perform the job of running a roof air.
People talk down the Chinese but at least they are innovative and attempt to make things work like a 24V 6200 btu unit
On the Yahoo Aliner group, a member runs his 4200 btu window unit on three 220AH batteries all night long.
Not all rvs need 15k btu roof airs. In Europe, Dometic makes much smaller units in the 3600 to 4500btu range, according to Dometic the U.S. market will never see them. Too bad, you could separate your rv space and run a small unit in one room on solar/battery.
It's the one size fits all mentality. Funfinder slaps a 13.5k unit on all of its TTs, from 13ft on up. In our 18ft, we used a 5000btu window unit and it would run all night on one gallon of gas in the Honda 2000. Worked great. In fact, Polar Cub is no longer available in the 7200 btu. What a shame.
Most people who do use battery for A/C don't talk about because they know the conversation is a losing battle. For now it takes a lot of battery, but don't rule out what you may think is the impossible.
qtla9111 wrote: So many nay-sayers. There is a lot of work being done in this area and there are many rvers who use solar/battery to perform the job of running a roof air.
People talk down the Chinese but at least they are innovative and attempt to make things work like a 24V 6200 btu unit
On the Yahoo Aliner group, a member runs his 4200 btu window unit on three 220AH batteries all night long.
Not all rvs need 15k btu roof airs. In Europe, Dometic makes much smaller units in the 3600 to 4500btu range, according to Dometic the U.S. market will never see them. Too bad, you could separate your rv space and run a small unit in one room on solar/battery.
It's the one size fits all mentality. Funfinder slaps a 13.5k unit on all of its TTs, from 13ft on up. In our 18ft, we used a 5000btu window unit and it would run all night on one gallon of gas in the Honda 2000. Worked great. In fact, Polar Cub is no longer available in the 7200 btu. What a shame.
Most people who do use battery for A/C don't talk about because they know the conversation is a losing battle. For now it takes a lot of battery, but don't rule out what you may think is the impossible.
It is NOT impossible, but unless you have the knowledge and skills to modify your system (99% don't) AND understand the limits and what can be done, then it is not practical for the normal Rv'er. That is why most (me included) will state it is not worth the discussion. Going offline and private conversations would be better for the few that want to attempt it. Going public would just bring up dangers that will not be discussed or highlighted. Doug
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