Power inverter for Flex VRG 3401--will this one work?

wascallyrabbit said:
guess alls good now that we're on the same page. i was just picked 1000w because thats about what the flex will draw.
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Haha, I edited my reply, I don't think we are on the same page.



I am confident that everything will work out just fine--I will let you guys know how it goes!
 
OK, from the electrical engineer--just to help people understand who may be searching this thread later:



Tell him that the current (amps) is the same on both sides because current remains the same at all points of a series circuit. However, "watt" is a measure of work (power) which is the product of volts and amps. So a 120V device that produces 1000 watts of power output draws 1000/120 = 8.3 amps. That 8.3 amp current is the same on both sides of the inverter because it is a closed (series) circuit but the wattage is 1000 on the 120V side and only 100 on the 12V side.
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amcdonal86 said:
OK, from the electrical engineer--just to help people understand who may be searching this thread later:
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http://www.majorpower.com/inverters/battery_sizing_faq.pdf



based on your engineers thinking my 1300w air conditioner should only be drawing around 11a (120v) out of my battery bank. on my trailer this most definitely not right is draws over 220a at 12v. i have a true sine wave inverter and it is drawing 220+ amps from the battery bank if i run the air conditioner from the inverter.



i agree current would be constant if you were dealing with a series circuit, but we are not dealing with anything close to a series circuit. what we are doing is changing direct current (dc) to alternating current (ac).



obviously you don't believe me so when you do hook up your inverter please take some current reading from what is coming out of the battery. i would suggest you use one of those clamp on amp meters that is capable of measuring 200 amps or so. but do feel free to up a ammeter is series with the battery output that measures only 20amp or so, cause according to your math it'll be alright. if i put my fluke meter in series to measure this current it would smoke it (hopefully just pop the fuze).
 
wascallyrabbit said:
http://www.majorpower.com/inverters/battery_sizing_faq.pdf



based on your engineers thinking my 1300w air conditioner should only be drawing around 11a (120v) out of my battery bank. on my trailer this most definitely not right is draws over 220a at 12v. i have a true sine wave inverter and it is drawing 220+ amps from the battery bank if i run the air conditioner from the inverter.



i agree current would be constant if you were dealing with a series circuit, but we are not dealing with anything close to a series circuit. what we are doing is changing direct current (dc) to alternating current (ac).



obviously you don't believe me so when you do hook up your inverter please take some current reading from what is coming out of the battery. i would suggest you use one of those clamp on amp meters that is capable of measuring 200 amps or so. but do feel free to up a ammeter is series with the battery output that measures only 20amp or so, cause according to your math it'll be alright. if i put my fluke meter in series to measure this current it would smoke it (hopefully just pop the fuze).
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How on earth could it possibly be drawing 220 amps at 12V? You would need several gas generators to generate that sort of electricity. Just look at the Honda EU3000i for a moment.:



Honda Generators - Model EU3000is



DC output is 12V, 144W (12.0A). I assume it has some sort of inverter built in-- AC output is 120V, 3000W (25A). Now according to you, this would mean that you can only run 144 watts off of it at 120V, which is ludicrous. You are saying you can't run two 100 watt lightbulbs off it. To run your air conditioner, you would need almost ten of these generators running together to power it...



I will report how well my setup works when I use it this weekend. I just hate all the misinformation that is spewed all over the web. In particular, there seems to be a lot of misinformation about inverters and electricity (even in the link you posted--where does it even mention 120V? All sorts of incorrect calculations.) that is dissuading people from using them. Heck, how many people on this thread just said "sounds like a bad idea, use a generator" without actually doing any calculations or thinkinga bout it?



I am pretty sure that my Mustang is capable of running more than 4-100 watt light bulbs...
 
generators are designed to put out 120v the generate ac not dc. the generator does not have an inverter it has a rectifier to make dc.



http://www.magnumenergy.com/Literat...ters/MS Series Data Sheet (64-0200 Rev F).pdf



scroll down to were it says "Rated input battery current" that is what the inverter input needs from your battery bank at max output.



the honda eu3000 would run the air conditioner just fine. it generates ac.



i know how an inverter works. it takes dc (normally 12v, 24v, 48v) and changes it to ac (almost always 120v). a generator makes ac and if it has a dc output it uses a rectifier to change the ac into dc.



its says it here: A full-sized refrigerator draws about 2 Amps at 120 Volts AC. By multiplying 2 Amps x 120 Volts, you find out the refrigerator uses 240 Watts. The batteries will need to deliver 20 Amps to run the refrigerator (240 Watts/12 Volts = 20 Amps).



you should probably do a little more research and maybe call a few places and ask about how inverters work and what the input requirements are.



ac and dc are not the same and are not interchangeable.



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How on earth could it possibly be drawing 220 amps at 12V? You would need several gas generators to generate that sort of electricity.



the inverter input needs 12v a 220 amps then changes it to 120v at 11amps. would one need one eu3000 to run the air conditioner.



DC output is 12V, 144W (12.0A). I assume it has some sort of inverter built in-- AC output is 120V, 3000W (25A). Now according to you, this would mean that you can only run 144 watts off of it at 120V.



this appear that you don't understand how dc or ac work. generator don't have inverters. the dc circuit can only handle 12vdc @12a (144w) this has nothing to do with the ac output at 120vac, 25a (3000w).



You are saying you can't run two 100 watt lightbulbs off it. not the 12vdc side.



not at all what i'm saying. i could run near 30 100w light bulbs of the eu3000.
 
:laugh:ha:laugh: good one deleting your post about the generator before i finished my post addressing it.



after you try it this weekend please post back on your results good or bad.
 
Yeah, I have a lot to think about. It seems you make a very convincing argument. :D



I will still let you guys know how it goes. I will need to be more judicious in my power usage, but at least the inverter has an automatic shutoff if the voltage if the battery voltage gets too low.



Thanks for trying to set me straight! Seems I'm going to jump off the cliff anyway.
 
Also, assuming that the MS2000 in your specs sheet is similar to mine, I will probably only be using the 900 watts continuously, so if 2000 watts requires 225 ADC input, then 900 might require only 101 ADC input, and if the alternator can charge the battery at 50-100 amps, then I might be ok, right? As long as I take long breaks?



I am still very confused, as I cannot imagine how anyone would ever be able to use a standard car battery/alternator setup as a backup source of energy for their appliances in an power outage/emergency situation. Surely you would overwhelm the alternator's ability to charge the battery!
 
amcdonal86 said:
Yeah, I have a lot to think about. It seems you make a very convincing argument. :D



I will still let you guys know how it goes. I will need to be more judicious in my power usage, but at least the inverter has an automatic shutoff if the voltage if the battery voltage gets too low.



Thanks for trying to set me straight! Seems I'm going to jump off the cliff anyway.
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the only problem i have with this is the alternator puts out a regulated 13.2-13.6v (typically) so while drawing power from the battery how can you tell if the battery voltage gets to low? i don't have the answer for this but guess i'll doing so more research on it.



i would also look at getting a battery charger. remove the battery from you car and recharge it that way.
 
amcdonal86 said:
Out of curiosity, how many amp-hours is a modern car battery (12V) rated for?
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depend on the group size but typically they range from 30-60 amp-hours. often time you can find it on the battery label as well.
 
amcdonal86 said:
Also, assuming that the MS2000 in your specs sheet is similar to mine, I will probably only be using the 900 watts continuously, so if 2000 watts requires 225 ADC input, then 900 might require only 101 ADC input, and if the alternator can charge the battery at 50-100 amps, then I might be ok, right? As long as I take long breaks?



I am still very confused, as I cannot imagine how anyone would ever be able to use a standard car battery/alternator setup as a backup source of energy for their appliances in an power outage/emergency situation. Surely you would overwhelm the alternator's ability to charge the battery!
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you would correct in saying that the less power you use the less power it will need from the battery. the 101adc you calculated will be in the ball park for a 120vac 900w load (the flex). i'm not sure how to calculate the run time you'll get from the battery with the alternator feeding it as we'll, my guess would be around 45mins. to prevent damage to the battery you'll need to recharge it before doing another cycle.



there is a lot more to running an inverter off you battery than meets the eye. for small loads you battery/alternator doesn't have a hard time, but once you start wanting to run large loads like a polisher and lights thats a whole different ball game. a car battery/alternator is not a good back-up idea for power outages. generators are what you would want for power outage or emergency's. as your learning it is quite easy to overwhelm your cars battery/alternator.



i would recommend a battery charger so when its all said and done you fully recharge you battery. you alternator doesn't quite ever fully recharge like a stand alone charger. i like and use vdc electronics battery chargers, but a cheap one from sear that puts out around 8-10amps would do fine. look for one that has the two or three different setting the low setting is usually 2amps, med 6-8 amps usually, for the high try not to go over 15 amps.
 
Yeah, it would be if I could find one that's 1000 feet long. My garage spot is actually a breezeway located underneath another apartment building down the street. I also live on the 7th floor of my building which is about 100-200 feet laterally from the nearest parking spot. Not to mention all the stupid looks I'd get.
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You never stated this in your original post.
 
Haha, I said there is no electrical hookup. If there is no electrical hookup, that means that there is no electrical hookup! :D



Shoot, I hope I get more than 45 minutes of polishing time out of this. I think I might just end up using an LED flashlight for inspection since I don't want to waste the battery power.
 
You gave the impression that this structure was a detached garage next to the house. No "haha" but definitely misleading.
 
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