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SMPS used at 110v instead of 230v Question??

C

Charger

Jan 1, 1970
0
I have 4 mobile phones and chargers, all different manufacturers.
(Sony, Siemens, Nokia, Motorola)

All apart from one (Sony Ericcsson) have labels stating 230v use only,
one states 110v-240v.

All seem to be made by Astec of China

All 4 give an indication on the phone that enough voltage is being
supplied to charge the phone when used at 110v, plugged into my bathroom
110v shaver socket.

Is it just a label thing, in fact are all these chargers capable of
being used on 110v, in America, without the need to buy a specific 110v
travel charger ?

As I understand it, they may be switched mode power supplies, the
technology I know very little about.

Does it do any harm to operate these chargers on 110v, instead of the
labelled 230v ?

How do I tell if it's switched mode from the outside, or if I open it up
?
Thanks
 
M

Michael Bohlender

Jan 1, 1970
0
Hi,

[email protected] (Charger) wrote in
All 4 give an indication on the phone that enough voltage is
being supplied to charge the phone when used at 110v, plugged
into my bathroom 110v shaver socket.

Quite strange! It seems as if they use a controller chip without
UVL (undervoltage lockout) that stops operation when driven with
too low a mains voltage.
Is it just a label thing, in fact are all these chargers capable
of being used on 110v, in America, without the need to buy a
specific 110v travel charger ?

Not sure about this, but a "normal" SMPS should not be operated
at excessive undervoltage because it works agains low input voltage
by drawing more current from the primary. When you use with it
half the nominal mains it draws twice the nominal input current
(roughly ...). And more current means more heat which is dangerous
for most power components.
Does it do any harm to operate these chargers on 110v, instead
of the labelled 230v ?

See above, it will probably not kill them immediately but they
will in any case suffer from that! The mobile chargers are
taken to the minimum cost point ... and cooling for the power
components is one of the most expensive things in such small
devices!
How do I tell if it's switched mode from the outside, or if I
open it up ?

Just compare the weight and size to a standard wallwart power
supply! SMPS do not use "heavy" metalcore transformers but small
and lightweight ferrite transformer.

BTW: The one stating 110-240V is surely a SMPS!

Regards
Michael
 
C

Charger

Jan 1, 1970
0
Not sure about this, but a "normal" SMPS should not be operated
at excessive undervoltage because it works agains low input voltage
by drawing more current from the primary. When you use with it
half the nominal mains it draws twice the nominal input current
(roughly ...). And more current means more heat which is dangerous
for most power components.
The charger doesn't get hot at 110v at all, no discernible temp rise at
all
 
R

Rich Grise

Jan 1, 1970
0
The charger doesn't get hot at 110v at all, no discernible temp rise at
all

If it's not specified, then the device isn't guaranteed - but if you've
already tried it, it worked, and you didn't burn the house down, why
are you asking? ;-P

Cheers!
Rich
 
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