# Question about 12 to 110 volt converters



## budgetprepp-n (Apr 7, 2013)

Hi,
I am setting up a small solar system and I am going to pick up a converter. My question is does
a 3000 watt converter use more electric to work than a 1000 watt converter? and if it does is it minimall?


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## PaulS (Mar 11, 2013)

A good inverter (12vdc to 110ac) will draw very little power when there is nothing connected to it but plan on a 10% loss in power through the inverter when it is running under load. (if your load is 15 amps then you will need a battery that supplies 17 amps) not important unless you are trying to calculate how long your batteries will last under a given load. Just divide your load by 9 and then multiply by 10 for the amount of amps in the "amp/hours" your battery can supply.


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## paraquack (Mar 1, 2013)

I think budgetprepp-n might mis-understand what you're trying to tell him. If the DC load is 15 amps, you'll draw closer to 17 amps from the battery every hour. If the AC load is 15 amp, you need to multiply the 15 times ten (= 15 amps DC) plus the 10% power loss for the inverter if you're using a 12 volt inverter. As an example, my TV in my motorhome draws 2.3 amps, 120 VAC. By actual measurement, the inverter is pulling close to 25 amps per hour (at 12 volts) from the battery every hour, averaged. If the battery is very well charged, it will take a little less. Since a 12 volt battery is ten times less voltage compared to 120 volts AC, you must multiple the AC amps times ten. On my motorhome, a well charged battery bank (4-6 volt, golf cart batteries (each battery is 115 amp hour) wired 2 in series for 12 volts and then those 2-12 volt banks are wired in parallel to give me 230 amp hours at 12 volts, would operate my TV for about 7 hours (the math says it should be 8.5 hours) before the battery voltage would drop too far and damage the battery.


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## rickkyw1720pf (Nov 17, 2012)

One of the first things to think about on what size inverter to use is almost anything with a motor will require a lot more starting current then running current. If your inverter is to small to start the motor it can damage your inverter or motor unless they are both protected. One of the big advantages of a battery and inverter is that a battery can give the large amount of starting current need to start a motor if the inverter is of proper size.


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## dwight55 (Nov 9, 2012)

budgetprepp-n said:


> Hi,
> I am setting up a small solar system and I am going to pick up a converter. My question is does
> a 3000 watt converter use more electric to work than a 1000 watt converter? and if it does is it minimall?


The simple and quick answer: yes. The 3000 watt converter will drain a battery 3 times as fast as the 1000 watt (on a "more or less" scale).

You always have to remember that with electricity, . . . you have to put just a little bit more in than you expect to get out, . . . and every conversion causes another "loss" of power, . . . whether it is heat or light or voltage change.

You want to read the labels on the stuff you want to use, . . . make sure the converter is big enough to run it. Label watts and converter watts are equivalent, . . . 1 for 1.

May God bless,
Dwight


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## budgetprepp-n (Apr 7, 2013)

So I might as well get a 3500 watt instead of a 1500 since it won't use any more juice and if something happens 
and I need the power I will have it. About right?


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## Montana Rancher (Mar 4, 2013)

dwight55 said:


> The simple and quick answer: yes. The 3000 watt converter will drain a battery 3 times as fast as the 1000 watt (on a "more or less" scale).


I disagree and that doesn't happen often with Dwight,

A 3000 watt INVERTER doesn't draw a continual 3000 watts, it only draws what the load requires. So a TV plugged into a 1000 watt inverter will draw the same amps from the battery as a 3000 watt inverter.

Back to the original question, a 3000 watt inverter setup is not a small system, unless you are going to run appliances I would stay in the 1000-1500 watt range. Most inverters will surge to double the rating for starting things up.


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## rickkyw1720pf (Nov 17, 2012)

I personally would get the largest inverter in my price range as a 1500 watt inverter running a 1200 watt heater is running at close to full capacity it will be running hotter then a 3000 watt inverter running the same heater and the 3000 watt inverter would probably last a lot longer under the same loads both would be putting the same load on your battery.

PS: This is just an example as I never would plan on using solar power to run a heater which uses so much power when you can get heat from so many other sources.


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## dwight55 (Nov 9, 2012)

Montana Rancher said:


> I disagree and that doesn't happen often with Dwight,
> 
> A 3000 watt INVERTER doesn't draw a continual 3000 watts, it only draws what the load requires. So a TV plugged into a 1000 watt inverter will draw the same amps from the battery as a 3000 watt inverter.
> 
> Back to the original question, a 3000 watt inverter setup is not a small system, unless you are going to run appliances I would stay in the 1000-1500 watt range. Most inverters will surge to double the rating for starting things up.


Absolutely correct ! The load determines how fast the power is used up.

Also correct, . . . the bigger unit you can buy, usually brings the "per watt" price down, . . . will "usually" run cooler under load, . . . and will probably last longer simply because it is running cooler and with less effort.

The only kicker to buying a large one, . . . all the eggs are in that basket, . . . if it goes south, . . . so does your 120 volt electric source.

I have not begun yet in that direction, . . . but when I do, . . . I plan on sizing those things I "have to have" powered, . . . add about 25% capacity, . . . and buy a converter specifically for that unit. Given the usual life and death of electronic gadgets, . . . that I perceive is the road which would give the most mileage, . . . a litttle more costly up front, . . . but probably better in the long run.

May God bless,
Dwight


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## Montana Rancher (Mar 4, 2013)

rickkyw1720pf said:


> I personally would get the largest inverter in my price range as a 1500 watt inverter running a 1200 watt heater is running at close to full capacity it will be running hotter then a 3000 watt inverter running the same heater and the 3000 watt inverter would probably last a lot longer under the same loads both would be putting the same load on your battery.
> 
> PS: This is just an example as I never would plan on using solar power to run a heater which uses so much power when you can get heat from so many other sources.


I agree the 3000 would run cooler at half capacity than a maxed out 1500 but I would suggest saving the $2-300 and get more batteries or solar panels if all you want to do is charge batteries, runs some lights and a laptop.


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## GTGallop (Nov 11, 2012)

I agree 100% with what the comments above reflect, but something I didn't see mentioned (or maybe I missed it) is around your power source.

You can have a 15KW inverter but if it is only hooked up to the 9 volt battery you scabbed out of a smoke alarm, then guess what... No Bueno.
Also if you are running a larger inverter like 3000 out of one battery you may (depending on battery quality) draw at a rate that causes heat and degrades the battery. So you need to pay just as much attention to your power source (batteries) and power re-generation (generators, wind, solar) as you do to the inverter itself.

Most people assume that an electrical circuit has no moving parts - but it does. The ELECTRONS move through the system and cause heat, wear & tear, and can eventually cause system performance issues. Just like anything else - your chain is as strong as the weakest link.

Pick a good generation system (I like the honda generators and inverter combos along with solar) and pick good batteries (I like those big honkin marine deep cycle batteries and buy 2x the number you think you need). Then cap it off with the right inverter (I prefer FULL SINE WAVE) and use energy efficient appliances and lights. You can light up a house with a low voltage 50 light string of LED X-Mas lights.

Don't skimp on cords either. The smaller (thinner) the wire, the more resistance it has. Also the longer it is, the more that resistance is multiplied. There is nothing wrong with running a night light off of the power cord from a MIG Welder.


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