# Portable detailing Q ....



## M40COO (Mar 21, 2006)

Guys,

Just wondered what the requirements for power are with regards to running a PC..

Physics/Electrics is not my strong point !

Not got my PC yet, so have not tried it ....but I do have a 2 stroke petrol generator.
I know the generator can run the voltage, ie transformer it to 110v.
It says 720w (which would not be enough to run a PC I dont think normally)

But how is the wattage affected by the change in voltage ?

ie could I run a PC off this generator?


----------



## Brazo (Oct 27, 2005)

Am sure you could mate PC draws 400w


----------



## M40COO (Mar 21, 2006)

400w ! Great - thats pretty neat then.

So ideally we could have a detailing day anywhere !


----------



## Dave KG (Feb 23, 2006)

M40COO said:


> But how is the wattage affected by the change in voltage ?


Will depend on the resistance of the device: P = (V^2)/R
so a device with a lower resistance will draw more power for a given voltage, because it drwas more current and...

...the current drawn - Power (Watts) = Current (Amps) x Voltage (Voltage)

If you up the current drawn, you up the power taken for the same voltage.

400W, 110V - the PC must be drawing ~3.6A, which sounds about right.


----------



## M40COO (Mar 21, 2006)

:lol: err think I got that Dave !
...so if it's drawing about ~3.6A - then will be fine for the presumably 13A rate plugs.

Maybe a bit of an overkill at car shows though - everyones quik detailing and I whip out a PC :buffer: :lol:


----------



## Dave KG (Feb 23, 2006)

If the device is drawing 3.6A, then I'd be tempted to run with a 5A fuse, as a 13A fuse may not blow fast enough in the event of a fault and the PC draws too much current...


----------



## ChrisGT (Feb 25, 2006)

Im shocked the PC must have bigger motor than 400W surely, I seen 2000W inverters for the car im sure one of them will do the trick


----------



## M40COO (Mar 21, 2006)

The generator was only £60 ..... 2000W invertors are £200 !


----------



## Dave KG (Feb 23, 2006)

Specs for the PC from their website - 120V AC, 3.7A motor. Now, the instantaneous power will be,

P = VI => P = 444W

This is from the DC equation, but the PC is working in AC so you need to accound the Power Factor to get the avaerge power of the motor... In AC, average Power, Pav:

Pav = [email protected], where @ is the phase angle between voltage and current:

[email protected] = R/Z where Z is the impedance of the PC, R is the resistance. If the impedance of the PC is purely resistive, then Z=R and [email protected] = 1, and therefore the Power Factor = 1... So the motor power will be,

P = 444 x 1 = 444W

Anyone know the impedance of the Porter Cable? Is it purely resistive?


----------



## ChrisGT (Feb 25, 2006)

M40COO said:


> The generator was only £60 ..... 2000W invertors are £200 !


ahh right never knew it was for a van or that lol, sure as hell i wudnt have a generator in ma car lol


----------



## Brazo (Oct 27, 2005)

Dave KG said:


> Specs for the PC from their website - 120V AC, 3.7A motor. Now, the instantaneous power will be,
> 
> P = VI => P = 444W
> 
> ...


What he said


----------

