Mr Whippy
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| posted on 27/6/08 at 01:31 PM |
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Whats the watts?
Sorry for being so ignorant 
Can anyone tell me if possible the wattage of this motor from –
12v – 11amps? Or is that not enough info???
ta
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Howlor
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| posted on 27/6/08 at 01:32 PM |
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P = IV so 132W
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Mr Whippy
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| posted on 27/6/08 at 01:33 PM |
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oh so simple thanks
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Howlor
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| posted on 27/6/08 at 01:35 PM |
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You are welcome
The only bit of my BEng I remember!
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rf900rush
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| posted on 27/6/08 at 06:05 PM |
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Don't forget Motor Watts in is higher than Watts out.
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Liam
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| posted on 27/6/08 at 06:07 PM |
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[geek]
That's assuming it's a single phase motor, which of course it almost certainly is being 12v.
Also 132W is the total electrical input, but the useful output will be somewhat less due to efficiency. The efficiency can vary widely depending on
the size and type of the motor, but you'll probably be looking at in the region of 70-90%.
[/geek]
Liam
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ChrisW
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| posted on 27/6/08 at 06:18 PM |
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Also...
A motor is an inductive load, so surely the input power will be slightly less than IxV?
Maybe... I was never that good at AC stuff! 
Chris
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Liam
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| posted on 27/6/08 at 06:24 PM |
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Well of course but I decided not to be that geeky! I'm assuming a 12v motor is DC and we're talking max output so no PWM to consider etc
etc. Therefore input power pretty much constant VI
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les g
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| posted on 27/6/08 at 06:26 PM |
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hi whippy
little phrase to we use to remember the formula is
Virgins Are Rare
V= volts A=amps R=resistance (in your case resistance is measured in watts ) simple triangle you can invert to get the other values
V
------------=AxR=V or V divided by R=A or
A R V divided by A = R
hope that helps
cheers les g
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JoelP
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| posted on 27/6/08 at 07:02 PM |
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Volts does indeed equal Amps times Resistance, but its usually expressed as
V=IR
with the current being I.
If you are measuring in watts then you are dealing with power, and power isnt in the equation above. Thats would be:
P=IV
which is why power as kilowatts is also sometimes called kilovoltamps.
The two can be combined to give
P=I^2 x R
but that can be a step too far for those who only want the basics.
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smart51
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| posted on 27/6/08 at 08:55 PM |
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Being a 12V DC fan, there will be a surge current at power up. The 11A quoted may be the max current, not the steady state current.
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JoelP
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| posted on 27/6/08 at 09:09 PM |
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quote:
Originally posted by smart51
Being a 12V DC fan
why are you so keen on 12v dc?!
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Liam
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| posted on 27/6/08 at 09:55 PM |
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Being a fan of 12v DC, i'm surprised you don't know such ratings on equipment are usually continuous ratings unless they specifically
state they are max ratings I love 12v DC too, but for me nothing can quite match 40v DC with a 5v pk-pk triangular wave ripple on top. Mmmmm
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martyn_16v
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| posted on 28/6/08 at 08:53 AM |
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You need to get out more
Besides, real men play with 1MV impulses
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