Volts/amps/inverters.

Hello members,
Question for the electrical gurus.
I understand a 175 Watt appliance running on 240 Volt would draw about 0.7 Amps.
A 175 Watt appliance running on 12 Volt would draw about 14.5 Amps.

Now if we run the same 240V appliance through a 12V/240V Inverter how do we work out what amperage is being drawn from the battery?

Cheers
Peter

Hey Pete,
You may find something here, basic Ohm's law!
http://www.ifigure.com/engineer/electric/electric.htm
Scotty

Nightjar wrote:
Now if we run the same 240V appliance through a 12V/240V Inverter how do we work out what amperage is being drawn from the battery?

Cheers
Peter

G'day Peter,

not sure of the answer here, but you would also need to take into consideration the fixed current draw of the inverter that you are useing plus the start up current draw of the appliance.
They may be shown on the appliances or in the tech info on the leaflets. - failing that you could use a set of clamp tongs to check the current draw while you were running them (provided you already have the appliances).

I'm not a sparky but someone should know have an idea of the theoretical calculation. A good question for Sandy !

Regards,

JK.

Hi All, A lot of people carnt under stand why a 300 watt inverter wont run their toster or the jug from home...
Its a number,s game..300 divided into 2000 you would need maybe 7 ..300 watt inverters to run your toaster.
now your toaster would use 8.3 amps on 240 volts. now 2000 watts from 12 volts mmmm. its around 8 amps per 100 watts..not good for your car batt.. best thing is a little old geny ticking over behind a bush.. and much cheaper as well. But if you want to know..Read on...

E=Itimes R
E is volts
I is in the amps
R is in ohms
this can be used in any direction..ei.I=E divied by R..or R=E divided by I.

Same type of law aplies to power..P=E times I..

P is the Watts
E is theVolts
I is the Ohms.

The best place to see this is at the back of a Dick Smith 08 Catalogue..
a heep of info about all sorts of gizmos ect..
Hope this is of some use..Bob..goldhog22

HiA
"175 Watt appliance running on 12 Volt would draw about 14.5 Amps.
Now if we run the same 240V appliance through a 12V/240V Inverter how do we work out what amperage is being drawn from the battery?"

The appliance itself will still draw about 14.5 amps from the battery BUT the inverter efficiency ,depending on type, size, make, could be between 50%<90%, so total draw could be as high as 22amps>16amps.[ie appliance draw + amps due to inverter losses