Who here is good with eletrical crap?

[lander2312]

I am curious if I have an electrical device that draws 115volts/60hz and 950 watts at 8.5amps and I wanted to run it with a convertor from battery power. How big of a battery would it take to run it for an hour? I am actually normally surprised at the intelligence level of the people on EF, especially in CC. so let the closet rocket scientist post!....lol

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[ceo]

plunkey is an EE, but he would probably tell you how to run it forever...tax free of course.

 

[WoodyO]

I am curious if I have an electrical device that draws 115volts/60hz and 950 watts at 8.5amps and I wanted to run it with a convertor from battery power. How big of a battery would it take to run it for an hour? I am actually normally surprised at the intelligence level of the people on EF, especially in CC. so let the closet rocket scientist post!....lol

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Running an AC on battery power?

 

[lander2312]

Yep a portable ac.

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[WoodyO]

Yep a portable ac.

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20 car batteries

 

[Fishak]

It depends on the ah(amp hours) rating of the battery.

C=8.5 a * 1 hour = 8.5AH

avg rate of use

C’ = 8.5AH / 0.8 = 10.6 AH

Then take the high rate into account

C’‘=8.5AH/.5 = 17AH

if u use a deep cycle with say 100 ah capacity

C=100/10.6ah=9.4 hours of capacity with avg use and 100ah deep cycle lead acid battery.

You "should" get 9.4 hrs minus rate of discharge= battery life at given usage.

I dont know how to calculate it exactly but its safe to say you will more than the 1 hr you require.
this is my guess, dont burn my house down if iam wrong.





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[nangiggles]

you need 8 AAA batteries

 

[lander2312]

Thanks that does help...i plan on running it for more than an hour just was hoping to have a base to start with. Would like to run it all night on my boat. No room in the bilge for a marine generator and an reg gen well I want to wake up in the morning, not die in my sleep. I think if a run 2 RV deep cycle batteries dedicated just to the unit it should power it easily for 10 hours.

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[Fishak]

I dont think you will get 10 hrs on 2 batts. Maybe 6ish. As you deplete the batt it becomes harder to run the item. Try running them in series and tye them to the generator whenever possible. What are you trying to run anyway

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[lander2312]

Its a portable airconditioner on my boat. It has a thermostat so it wont be running continuously for 10hrs...but by the previous formula then if I can get 5hrs per battery then 2 should grt me close to 10. This is why I made the post, cause never tried anything like this before.

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[Fishak]

Cool, I know ac units draw a ton of amps when they first kick on then back off. I hope it works out. Tell me how it goes.

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[lander2312]

Yeah I think what I am going to do is grab 2 batteries and hook it up up my garage and do a trial run first. Usually the windows open and the breeze being on the middle of the lake is enough but the past 2 summers here in Tennessee have been miserable. 2 summers ago it was still in the 90's at midnight.

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[lander2312]

PLUNKY....help a brother out....!

 

[brownbrown]

Thats a shit ton of running for 2 12v batteries. Running them in series will bring up the DC Volts to 24 but the run the batteries at a harder rate.

Parallel will stress the batteries less, current will be higher, but the Voltage will be 12 volts. And if one fails it will draw more for the good battery to charge and stress that one more.
A genny would be better long run.
Fish is right, Deep cycle battery.

Are you going to be charging these batteries off an alternator after you run them all night?

 

[ceo]

You need a 400% efficient turbine for that shit.

 

[nangiggles]

apricot seeds will give it enough energy for about 48 hours

 

[brownbrown]

a small genny will fix all his ailes

 

[WoodyO]

I wasnt joking. You'll need about 20 car batteries for this.

 

[ceo]

why not use a fan blowing right on you instead?

 

[brownbrown]

why not use a fan blowing right on you instead?

↑↑↑↑↑↑↑↑↑↑
this makes perfect sense

 

[lander2312]

Brown, cant use a gennie as stated earlier. the exhaust fumes are heavier than air and if the wind shifted while asleep...well thn we would never wake up. Yes I know I could get a deterctor but not willing to risk my life that it will work properly. I cant install a marine generator due to know room left in the bilge after the engine, water tank, waste tank, hot water heater.

CEO, it has 3 fans on it and that is normally pleanty. After dark when ready to go to sleep it really cools down hen your on the water. The problem is that the past 2 summers in TN its been so hot and muggy that even around midnight it is still hot outside.

A car stereo guy got me thinking about this way. He said no way would it work for the whole weekend but that 2 deep cycle batteries should run it for a night. This is why I came to my all knowing juice bros...i mean we play doctor, chemist, counselor, hell why not back yard mechanic....lol. I appreciate the input so far.

 

[RickRock13]

Im an electrician, but Why not get a DC to AC inverter (12V DC to 120V AC) and run it straight off of your boat battery that way?

 

[lander2312]

Im an electrician, but Why not get a DC to AC inverter (12V DC to 120V AC) and run it straight off of your boat battery that way?

I am going to be using an inverter, just going to dedicate the 2 batteries for nothin but the ac unit. That wat i still have 2 other batteries for cranking the engine and running other electronics on the boat. I am just trying to figure out if its even possible.

 

[kx250rider]

There is a lot of math involved that I won't get into (the Peukert coefficient), etc. , and what I mean is that as the battery starts to go down, the load goes up, and therefore the faster it goes down. Also the batteries deplete by making internal heat, so to use the item for a steady hour is much more of a drain than to use it for 15 minutes or so, and rest it an hour, etc. You also have to consider the loss from the inverter having to work to convert the DC to AC, and there will be fans running in an inverter that big, etc.

My advice: four 6v golf cart batteries (Costco $80 each). Forget car or RV deep cycle batteries, as the amp hour rating is calculated differently, and cca (cold cranking ams) are nothing to do with amp hours of power available. A golf cart battery is designed very differently, to deliver the maximum force all the way 'til it's nearly down, but a car or deep cycle battery is designed to give a huge boost for a few minutes, then it's already starting to drop voltage right away. For the 6v golf cart batteries, you would hook them up to give 12v at appx 350 Amp hours (after loss and a fudge factor), which should run the 950w item for at least 2 hours continuous, or maybe 3 hours on & off. The thing is, you can get an Onan generator smaller and lighter than four golf cart batteries and an inverter, and maybe about the same cost. You could try two 6v golf cart batteries, but that's pushing it. If you try two of them first, you would have the two batteries wired in series with an 00 gauge cable between the two 6v batteries (+ on one of them to - on the other), and then the inverter gets connected to the remaining - on one and the remaining + on the other. BE SURE YOU GOT THAT HOOKUP RIGHT, or you could have an explosion and lose your face! The hookup for four is two in parallel, in series with two more in parallel. It's something I'm having a brainfart and can't write a good description ithout it being dangerously confusing, but will be happy to draw a diagram if you're not clear on that, or if you can't find it on Google...

Charles

 

[lander2312]

Thanks KC that does make sense and i was actually looking at the 6v seeing how it would work with my inverter. I wish i was more comfortable with using a nice small honda gen off the swim platform but man dying in the bottom of the boat during my sleep...hell the thought freaks me out. I looked in to an Onan gen set but paying 5grand makes no sense. I would be better of selling the baot and upgrading to one with a gen set already installed. Thanks for the advice and if you think of anything else feel free to ad it here.

 

[PICK3]

a small genny will fix all his ailes

+1

 

[kx250rider]

I looked in to an Onan gen set but paying 5grand makes no sense. I would be better of selling the baot and upgrading to one with a gen set already installed. Thanks for the advice and if you think of anything else feel free to ad it here.

I see Onan propane or gasoline gensets on CL now & then for $1200, taken out of wrecked RVs, and some that people removed for upgrades in nearly new shape with paperwork and warranty... A good well-filtered inverter is about $500, and the 6 golf cart batteries and cables will total about $650. So it could be about the same.... I can't speak from any experience as to noise, but they're pretty quiet. Probably barely louder than the hum of an inverter running.

Charles

 

[lander2312]

I see Onan propane or gasoline gensets on CL now & then for $1200, taken out of wrecked RVs, and some that people removed for upgrades in nearly new shape with paperwork and warranty... A good well-filtered inverter is about $500, and the 6 golf cart batteries and cables will total about $650. So it could be about the same.... I can't speak from any experience as to noise, but they're pretty quiet. Probably barely louder than the hum of an inverter running.

Charles

I will look into that...the other problem is it being in the bilge and not being Marine rated...meaning spark arrestor and sealed contained units due to the fumes that thend to pile up in the bilge. I have been researching it alot the pst few days and i am leaning more towards a nice honda eu2000 and about 3 battery powered CO detectors in the sleeping quarters. HAve to see how the wind blows tomorrow.

 

[musclemom]

Seriously, why don't you just overnight on the boat when it's cooler? Cheaper and less to think about. My husband and I won't camp in July and August because it's too damned hot in our trailer even with the AC, no big loss.

 

[lander2312]

Ummmm boating season is during the summer....

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