In-car chargers - will they damage my MP3 player?

[bobr05]

Hi,
Does anybody know if I use a 5V, 0.8A adaptor plugged into my car's
cigarette lighter to charge my MP3 player (that is supposed to be
charged with a 5V, 1.6A charger), will it do any damage, to either the
MP3 player or the charger?
My guess is it should be OK, since the current output from the charger
is less than what the player can take, but a colleague reckons that
the player will try to draw more current from the supply and do some
harm to either it or the charger.
What do the experts think?
Many thanks.
Bob

 

[Don Bruder]

Hi,
Does anybody know if I use a 5V, 0.8A adaptor plugged into my car's
cigarette lighter to charge my MP3 player (that is supposed to be
charged with a 5V, 1.6A charger), will it do any damage, to either the
MP3 player or the charger?

You'll cook off the charger. You're asking a unit tagged for 0.8 amps to
supply twice its rated output. Not a good situation no matter how you
look at things.

My guess is it should be OK, since the current output from the charger
is less than what the player can take,

Your guess is totally wrong, in every way that it possibly can be - It's
exactly the reverse of reality.

The *DEVICE*, not the supply, determines how many amps will be drawn
from the supply. The supply's rating is an "I am capable of pushing up
to this many amps if you need it, but no more" number. The device's
rating is an "I'm going to try to pull this many amps from the supply"
number. If the device's number is higher than the supply's number, the
result is going to be a fried supply. How the supply cooks off is going
to be a function of how overloaded it is - A slight overdraw may just
quietly go "pfft" and let out a wisp of smoke. A major overdraw can
literally turn the supply into a bomb.

When choosing a supply for a device, the specified voltages must always
match, or the device is likely to be either damaged (if volts too high)
or non-functional (volts too low), and the amp rating of the supply must
be equal to or greater than the amp rating of the device, or the supply
will likely be damaged.

but a colleague reckons that
the player will try to draw more current from the supply and do some
harm to either it or the charger.
What do the experts think?

Your colleague is correct. You're almost certain to fry the charger if
you make the attempt.

 

[CWatters]

Hi,
Does anybody know if I use a 5V, 0.8A adaptor plugged into my car's
cigarette lighter to charge my MP3 player (that is supposed to be
charged with a 5V, 1.6A charger), will it do any damage, to either the
MP3 player or the charger?
My guess is it should be OK, since the current output from the charger
is less than what the player can take, but a colleague reckons that
the player will try to draw more current from the supply and do some
harm to either it or the charger.

No your colleague is correct. The current sucked out of the charger depends
on the load. The MP3 player spec says it needs 1.6A so your 0.8A charger
would be overloaded.

 

[bobr05]

OK, thanks to both of you. I'll just have to buy a correctly rated
supply - a load of melted plastic in my car isn't what I was looking
for!
Cheers.