Just purchased a HP Envy from USA, question regarding power adapter use in the UK.

Hey all,

My friend just bought over this beauty today! I was a little confused on the adapter front, my question is regarding the cable connecting the power brick to the mains. As I live in the UK, I can't use the one supplied without a travel adapter, I had one cable lying from my old laptop and I was wondering whether this was safe/compatible to use.

The old cable has a 3A fuse and 250V
The new USA cable is 7A and 125V

The power brick states Input as 100-240V V~1.6A 50-60Hz and Output as total 90W 19.5V 4.62A

Can someone tell me if using my old cable is safe?

Just to be clear, I'm using the power brick supplied with the new Envy.

Thanks in advance,
Shaizer

 

As long as you use the power brick for the Envy you are in good shape to swap the cable going from the brick --> wall. I've done the same in reverse with a few laptops purchased overseas, then brought to the states.

 

U can use it without problems, the ac/dc power supply for laptops are made to work universally in almost all the power grids in the world, because the power brick it's a SMPS(Switch Mode Power Supply). So if the input is from 100-240V then will work on 110V US grid and 220 V europe grid. The freq of the AC doesn't matter because it will be rectified an converted to DC inside the adapter.

 

Worst case, you'll have to put a 7A fuse in the UK plug, but it should work fine.

If the fuse blows, just swap it out for a 7A one.

 

Please ignore what chez suggests.

If the fuse blows, there is a problem.

With a lower voltage (125V) you will need higher Amperage to get to roughly the same Power (Wattage) input.

With the higher voltage (240V) you need much less Amperage to have the same amount (roughly...) of Power.

The formula is as easy as PIE:

P=I*E is:

P=Power in Watts
I=Current
E=Voltage

So 7*120=875Watts on the American Power grid

and 3*240=720Watts on the British Power grid.


Note that that is not what the AC adaptor is rated for - that is simply what the AC power CABLE is rated for (at the specified voltage).

With a 7A fuse on a 240V Grid, the power (watts) which will be allowed is 1680W to the AC Adaptor. The adaptor might be able to handle that kind of input for a while, but the specifications here is that the Cable is not designed to handle it.

With a maximum power input of 1.6A @ 240V (384Watts) as specified by the OP, either cable is capable of powering the AC Adaptor properly.

No changing of the fuse(s) needed.

Hope this clears this up.

 

Thanks for this info! My dad pretty much said the same thing about the P=IV, its funny because I did Alevel physics so I should have been able to reassure myself. I guess I'm not really good at applying my science

Thanks all for the advice!

-Shaizer

 

Cables have fuses?

 

The power brick has a fuse in it, just like most power supplies.
But since we consumers dont fiddle inside them they go unoticed.