I would like to know how many AMPS is the consumption on 12 VDC to calculate the converter for 120 ac.

Thank you

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If you want to get more precise, figure out everything in terms of power (watts).

Basic electrical rule 1, 2 and 3:

voltage x current = power

or re-arranged:

current = power divided by voltage

or re-arranged:

voltage = power divided by current

For example, 12V X 2 amps = 24 watts.

or another example, 400 watts divided by 120 Volts = 3.33 amps

A 55W headlight that uses 12V would draw 55 /12 = 4.6 amps @ 12V

A 55 watt light bulb in a lamp at home would draw 55 / 120 = 0.46 amps @ 120V

As the previous post mentioned, inverters are not perfect when
convertering 12V into 120V. If the converter consumes 1000W from the
12V battery, then a 90% effecient converter would generate 900W of 120V
AC power best case. The other 100W is lost primarily as heat.

The other thing that gets tricky is that these ratings and the formula
above are used for resistive loads, like light bulbs or hair dryers.
Anything with a motor or transformer is considered an inductive load
and can get much more tricky to calculate.

Consequently you need to give your self a safety margin when figuring out how big an inverter you need.

How does work in a practical sense?

Lets say you want an inverter for TV, DVD and Sat. Receiver. Look at
the back of TV or in the manual. It should say how many watts it
consumes. Lets say it is 400W. The DVD might be 100W and the Sat.
receiver 50W - just as an example.

400 + 100 + 50 = 550 Watts. (just as an example)

You might think, well no problem, I'll use a 600 Watt inverter and have
50 watts left over. Depending on your inverter, that 600W might really
be 600 x 90% effecient = 540 Watts of AC, less a 20% margin of error
for the inductive transformers in the electronic of the TV, DVD and
Sat. receiver 540 - 20% = 432 Watts.

Now you can see your 600 Watt inverter isn't big enough to do the job.

If we really need 550 watts of AC, add 10% to make up the effiency loss, then add a safety margin for inductive loads.

550 + 10% = 605 + 20% = 726 Watts.

Sounds more like an 800W inverter fits the job.

What does that mean in terms of wiring the 12V batteries to the inverter?

from the formula above:

current = power divided by voltage

In our example, we have an 800W inverter that runs on 12V

The current would thererfore be:

current = power divided by voltage

current = 800 watts divided by 12V

current = 66 amps.

That is important info because you can not use light gauge wire to
carry 66 amps worth of 12V to the inverter nor could you use a 20A fuse
to protect your inverter.

Now that's a lot of science for a guy who just wants to run a toaster on an inverter right?

800W / 120V = 6.66 amps

Using garryp's ratio 11:1, 6.66 x 11 = 73 amps.

That is a good ratio with a good safety margin.

This is all just MHO and should not taken as solid technical advise. In other words, don't blame me if you blow yourself up.

Posted on Nov 26, 2008

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Good luck!

Posted on Jan 02, 2017

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Check the nametag on the fridge and take note of the total amperage draw of the unit. That that reading, and multiply it by 120 volts and the resultant answer will the the total wattage of the unit... If you want to get it precise, measure the applied voltage at the receptacle where it is plugged in. Your 120 volt circuit may really be supplying 125 volts or more and that will effect the calculation....though minimally.

Apr 05, 2015 | Freezers

you are missing the voltage supply here to get an definitive answer

for 240 volts drawing 4.8 amps the required wattage is 1152

for 120 volts the wattage is 576 watts

for 120 volts with a current of 900 watts , it equates to 7.5 amps

with 240 volts with a current of 1150 watts , it equates to 4.79 amps

so you can see the problem by not stating the supply voltage

get access to an cable clamp amp meter / watt meter from an electrician and read the current on starting the ac unit

if it exceeds 900 watts for 120 volts or 1150 for 240 volts , consider a bigger generator

for 240 volts drawing 4.8 amps the required wattage is 1152

for 120 volts the wattage is 576 watts

for 120 volts with a current of 900 watts , it equates to 7.5 amps

with 240 volts with a current of 1150 watts , it equates to 4.79 amps

so you can see the problem by not stating the supply voltage

get access to an cable clamp amp meter / watt meter from an electrician and read the current on starting the ac unit

if it exceeds 900 watts for 120 volts or 1150 for 240 volts , consider a bigger generator

Aug 31, 2017 | Fixya.com Heating & Cooling

I don't know if i'm not reading your question right...but an inverter is an equipment that takes 12 Volts DC and transforms it into 120 AC. The input is a 12 VDC not 125 V.

May 29, 2013 | Boating

Ohm's law tells us that: volts = amps x resistance and watts =volts x amps. Watts (300) = volts (240) x Amps (?); or 300 / 240 = 1.25 Amps That means the inverter can supply up to 1.25 Amps to a 240 volt load.

The primary is 12 volts, this is just 1/20th of the secondary 240 volt output. Since the best you can ever get is 100% efficiency -this means you'll need to supply 20 times the current. 1.25 Amps (at 240V) x 20 = 25 Amps (at 12V). As a check, from above Ohm's law that states Watts=Volts X Amps we get: 12VDC x 25Amps = 300Watts. Check!

Some side notes. The Ohms law used above is for DC circuits and purely resistive loads on AC circuits. I do not know what your 1.25 A @ 240VAC load is - but I suspect it won't be purely resistive. Also, since we're working with an electronic inverter as opposed to a transformer and DC rectifier there are some things that push losses higher. You might need to provide a 30 Amp 12 VDC source voltage in order to provide the 1.25A @ 240VAC output. Lastly, I wouldn't not run the output at maximum for long periods of time - or at all. 1 Amp @ 240VAC would be much better.

I hope this answered your question & good luck! Please rate my reply - thank you.

The primary is 12 volts, this is just 1/20th of the secondary 240 volt output. Since the best you can ever get is 100% efficiency -this means you'll need to supply 20 times the current. 1.25 Amps (at 240V) x 20 = 25 Amps (at 12V). As a check, from above Ohm's law that states Watts=Volts X Amps we get: 12VDC x 25Amps = 300Watts. Check!

Some side notes. The Ohms law used above is for DC circuits and purely resistive loads on AC circuits. I do not know what your 1.25 A @ 240VAC load is - but I suspect it won't be purely resistive. Also, since we're working with an electronic inverter as opposed to a transformer and DC rectifier there are some things that push losses higher. You might need to provide a 30 Amp 12 VDC source voltage in order to provide the 1.25A @ 240VAC output. Lastly, I wouldn't not run the output at maximum for long periods of time - or at all. 1 Amp @ 240VAC would be much better.

I hope this answered your question & good luck! Please rate my reply - thank you.

Mar 09, 2011 | Electronics - Others

If it works on gas and NOT electricity then the heating element is not getting power or the heating element is open. The heating element is located on the tubing just aft of where the pilot flame is on the bottom of the copper tube. You should check for power to the heating element and with power off perfom a continuity check on the element. I really do not at this time think you have a heating element problem.

There is a 120VAV element a AND a 12VDC element. The chances of both of these failing at the same time is pretty slim.

There is a note in the manual:

If the gas only pushbutton is depressed the

lamp will illuminate green and the refrigerator

will only operate on the LP gas mode, even if q

120 or 12 volts are available.

Another significant change in the third

generation A.E.S. system is how the 12 volt

heating element mode operates. As with the

first and second generation series, the 12 volt

heating element circuit is energized by the

ignition lock terminal. This terminal receives

its DC voltage from a wire that runs from the

run side of the vehicle’s ignition switch to the

refrigerator’s ignition lock terminal. This

allows the 12 volt heating element to be

energized only when the RV is traveling down

the road.

When the ignition lock terminal is energized

by the ignition key, the printed circuit board

must see at least 13.3 volts DC for a period of

40 seconds before the system will activate the

12 volt DC heating element.

If 13.3 volts is not achieved in this time frame,

the electronics will light the LP gas burner and

the refrigerator will operate on the LP gas

mode.

**
LOWER THAN 13.3 V.D.C. =LP Operation**

If the battery voltage remains low after the

delay cycle, the automatic controls will light

the refrigerator on the LP gas mode and stay

on the gas mode until the printed circuit board

sees approximately 13.3 volts DC to the

terminal block.

For proper cooling on the AC mode, the AC

voltage to the refrigerator should not vary

more than 10 percent from the voltage rating

on the heating element. Heating elements used

in Dometic refrigerators could have a rated

voltage of 110 volts, 115 volts or 120 volts AC.

Because of this, the power requirements for

each differently rated heating element will

vary. For example, if a heating element is

rated for 100 volts, the acceptable power range

would be between 99 to 121 volts AC. If an

element is rated for 115 volts, the acceptable

power range would be between 103.5 to 126.5

volts AC. If the heater is rated for 120 volts,

the acceptable AC power range would be

between 108 to 132 volts AC.

The unit to operate on either AC or DC must have 13.3 volts to the unit. I think this is where your problem lies in that the battery voltage is less than 13.3 VDC

If all of that checks good just repsond here and I will help you. There is still more that can be checked.

Thanks for choosing FixYa.

Kelly

There is a 120VAV element a AND a 12VDC element. The chances of both of these failing at the same time is pretty slim.

There is a note in the manual:

If the gas only pushbutton is depressed the

lamp will illuminate green and the refrigerator

will only operate on the LP gas mode, even if q

120 or 12 volts are available.

Another significant change in the third

generation A.E.S. system is how the 12 volt

heating element mode operates. As with the

first and second generation series, the 12 volt

heating element circuit is energized by the

ignition lock terminal. This terminal receives

its DC voltage from a wire that runs from the

run side of the vehicle’s ignition switch to the

refrigerator’s ignition lock terminal. This

allows the 12 volt heating element to be

energized only when the RV is traveling down

the road.

When the ignition lock terminal is energized

by the ignition key, the printed circuit board

must see at least 13.3 volts DC for a period of

40 seconds before the system will activate the

12 volt DC heating element.

If 13.3 volts is not achieved in this time frame,

the electronics will light the LP gas burner and

the refrigerator will operate on the LP gas

mode.

If the battery voltage remains low after the

delay cycle, the automatic controls will light

the refrigerator on the LP gas mode and stay

on the gas mode until the printed circuit board

sees approximately 13.3 volts DC to the

terminal block.

For proper cooling on the AC mode, the AC

voltage to the refrigerator should not vary

more than 10 percent from the voltage rating

on the heating element. Heating elements used

in Dometic refrigerators could have a rated

voltage of 110 volts, 115 volts or 120 volts AC.

Because of this, the power requirements for

each differently rated heating element will

vary. For example, if a heating element is

rated for 100 volts, the acceptable power range

would be between 99 to 121 volts AC. If an

element is rated for 115 volts, the acceptable

power range would be between 103.5 to 126.5

volts AC. If the heater is rated for 120 volts,

the acceptable AC power range would be

between 108 to 132 volts AC.

If all of that checks good just repsond here and I will help you. There is still more that can be checked.

Thanks for choosing FixYa.

Kelly

Aug 24, 2010 | Dometic RM2652 Refrigerator

there is no such thing as "ac/dc" current-its either one or the other--if its a 120 Volts then chances are it is AC already-at 60hz---the 15 Watts or any Watts is the amount of draw from the unit-not the power supplied to it- Watts= Volts(supplied)/Amps(being used) if you only want to supply 15 watts then reduce the amps (with a fuse) to .125amps

Mar 26, 2010 | Computers & Internet

This is a copy from the Radio Shack site. The quick answer is go to pretty much any electronic store or most travel stores and buy a Foreign Power Converter.

*AC to AC Power Conversion (Foreign Voltage Converters)*
Purpose of Converter / Explanation of Operation
AC-to-AC
voltage converters, or travel converters, are designed to convert the
voltage used in a foreign country to the voltage required for a
particular AC device. These converters are either transformer-based or solid-state,
and this affects what type of devices the converter can power. In
addition to converting the power, you will often need to also use a plug adapter.
Plug adapters are generally either built into the converter, or
provided as separate parts. They are also sold separately, for use with
multi-voltage devices that are designed to convert the power internally.

Selecting a Converter These are one of the more confusing of the power conversion devices. Because of the range of voltages, plug types and converter designs, many customers find that they need help determining exactly which converter they need. To aid in that process, we have put together a short worksheet to help you determine what type of converter is needed: We recommend that you print out thi sheet when taking a number of different devices to a different country.

First, you should determine the electrical requirements (voltage, frequency, and wattage) for the device(s) you will be taking with you. This information is generally on a label or embossed into the back or bottom of the device. Make a note of the voltage(s), frequency or frequencies, and the wattage indicated for each device.

Cautions

Selecting a Converter These are one of the more confusing of the power conversion devices. Because of the range of voltages, plug types and converter designs, many customers find that they need help determining exactly which converter they need. To aid in that process, we have put together a short worksheet to help you determine what type of converter is needed: We recommend that you print out thi sheet when taking a number of different devices to a different country.

First, you should determine the electrical requirements (voltage, frequency, and wattage) for the device(s) you will be taking with you. This information is generally on a label or embossed into the back or bottom of the device. Make a note of the voltage(s), frequency or frequencies, and the wattage indicated for each device.

- The voltage may be given as either V, VAC or VDC. The standard voltage for US devices is 120 V. Devices that are designed to operate using different input voltages will be labeled, such as 110/120 V, or 120/240 V.
- The frequency will be given in Hz. The standard frequency for US devices is 60 Hz. Devices that are designed to operate using different frequencies will be labeled, such as 50/60 Hz.
- The wattage will be given in either watts (W) or volt-amps (VA). If the wattage is not listed on the device, you will need to contact the device's manufacturer for this information. If you have the maximum current consumption (in amps), you can calculate the wattage by multiplying the voltage (V) times the current consumption (A).

- Look up the country you will be visiting on our Guide to Worldwide Electrical Voltages, Frequencies and Plug Types.
- Make a note of the voltage(s), the frequency (50, 60 or 50/60 Hz) and the plug type(s).

- If your equipment accepts the voltage and frequency provided by the country you will be visiting, then only a
**Plug Adapter**will be required. - If the voltage of the target country is higher than the voltage required by your device(s), you will need a
**Step-Up Voltage Converter**. - If the voltage of the target country is lower than the voltage required by your device(s), you will need a
**Step-Down Voltage Converter**.

Cautions

- The AC outlet in many foreign bathrooms is for low-wattage devices only. To avoid damage to your converter and/or attached device, check with your host or hotel before powering a high-wattage device (such as a hair dryer) from this plug.
**Do not**use a voltage converter with electronic devices such as televisions, VCR's and computers unless the device indicates that it can handle both 50 Hz and 60 Hz.**Do not**use heating appliances, such as hair dryers, irons and coffee-makers, on a transformer-based voltage converter.**Do not**use non-heating electronic devices, such as calculators, electric razors and portable audio players, on solid-state voltage converter.**Do not**use 110-120 VAC Surge protectors or Uninterruptible Power supplies on a 220-240 VAC system. Even with a step-down power converter, damage could occur as the two power systems are wired differently.

Sep 22, 2009 | Toshiba Satellite L305D-S5895 Notebook

Here are a few ways to calculate your BTU's.

Get ready to use that algebra you thought you'd never use.

1 Ton = 12000 BTU's

400cubic feet per minute (CFM) = 1 Ton on standard ac units (300 is an absolute minnimum)

BTU's air heat = difference in temp. ( ∆T ) x 1.08 x CFM

∆T = BTU's / (1.08 x CFM)

i.e. 65◦F entering your unit and 93◦F air leaving on a 12000BTU unit.

∆T = 28

CFM = 400

28 x 1.08 x 400 = 12096BTU's

Another way...

Electric heat calculations.

BTU's = KW (killowatts) x 3413

Watts = Volts x Amps (single Phase) Most Homes))

Watts = Volts x Amps x Phase (this is for three phase units.)three wires and a ground))

120 volts 30 amps single phase (common)

120 x 30.0 x 1 = 3600 or 3.6KW 3.6 x 3413 = 12286BTU's

Get ready to use that algebra you thought you'd never use.

1 Ton = 12000 BTU's

400cubic feet per minute (CFM) = 1 Ton on standard ac units (300 is an absolute minnimum)

BTU's air heat = difference in temp. ( ∆T ) x 1.08 x CFM

∆T = BTU's / (1.08 x CFM)

i.e. 65◦F entering your unit and 93◦F air leaving on a 12000BTU unit.

∆T = 28

CFM = 400

28 x 1.08 x 400 = 12096BTU's

Another way...

Electric heat calculations.

BTU's = KW (killowatts) x 3413

Watts = Volts x Amps (single Phase) Most Homes))

Watts = Volts x Amps x Phase (this is for three phase units.)three wires and a ground))

120 volts 30 amps single phase (common)

120 x 30.0 x 1 = 3600 or 3.6KW 3.6 x 3413 = 12286BTU's

Aug 09, 2008 | LG BG8000ER Air Conditioner

you need a clamp on amp probe, a multimeter wont hack it. if you can get a amp probe, you first seperate the wires on your cord and then place the probe over one of the wires only this will give you your consumption. by the way, your approx usage of watts on a 26 inch lcd tv would be 160 watts. models do vary.

Mar 29, 2008 | Televison & Video

Most likely 350 or there abouts.

I tried to look up the specs but VGN -NR17G is not a known model number.

I tried to look up the specs but VGN -NR17G is not a known model number.

Jan 28, 2008 | Toshiba Satellite M35X-S111 Notebook

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