cordless phone power adapter, using one less then required.

[fox]

My cordless phone/charger uses a 9volt DC 200ma power converter, I was
wondering if I used a 9 volt DC 100ma power converter if there would be any
big safety hazard. being a 100 ma less, i was thinking would this only allow
my phones batteries to charge slower, or would the power convertor draw more
power to charge the batteries.
The reason I'm asking is i have a 100 ma one and dont want ot go out and buy
200 ma one.

Can someone give me an opinion on this weather it will work safely or would
this effect the cordless phone batteries.

 

[NSM]

| My cordless phone/charger uses a 9volt DC 200ma power converter, I was
| wondering if I used a 9 volt DC 100ma power converter if there would be
any
| big safety hazard. being a 100 ma less, i was thinking would this only
allow
| my phones batteries to charge slower, or would the power convertor draw
more
| power to charge the batteries.
| The reason I'm asking is i have a 100 ma one and dont want ot go out and
buy
| 200 ma one.
|
| Can someone give me an opinion on this weather it will work safely or
would
| this effect the cordless phone batteries.

Bad idea. I would expect the wall wart to smoke out. You'll be drawing 200
mA from an undersized adaptor. Bigger is better - 200 mA and up is OK.

N

 

[Bobby Villamor]

A DC power converter provides power (in m.a. or amp) only what is needed by
the
circuit. The smaller the power it supplies compared to its maximum ratings,
the cooler
is the body temperature while it is in use. It gets a little warmer when the
circuit it provides
draws power closer to the converter's maximum ratings.
You may try using your 100ma for charging and monitor it's body temperature.
Anyway,
if it can't supply enough power, the last thing that would happen is that
it's primary winding
opens (cuts) (due to too much work) and that's the end of it's life. I don't
think there are
possible dangers involved.
Bob

 

[w_tom]

Those who solve problems the first time use simple
inexpensive tools such as a screwdriver and a 3.5 digit
multimeter. No one an tell you how much your phone draws just
as no one can tell you whether the 100 ma adapter is polarized
positive or negative center tip - another important fact.

How much does the phone draw? Connect phone to nine volt
battery and meter - and measure the current.

Will an overloaded wall wart be dangerous? Any power source
can even be short circuited and still not catch fire. If a
100 ma wall wart driving a 200 ma load becomes a hazard, then
call the Product Safety Commission so they will institute a
nationwide, emergency product recall. No power supply should
ever be destroyed when overloaded or short circuited - for
fundamental electrical reasons.

 

[Ross Herbert]

My cordless phone/charger uses a 9volt DC 200ma power converter, I was
wondering if I used a 9 volt DC 100ma power converter if there would be any
big safety hazard. being a 100 ma less, i was thinking would this only allow
my phones batteries to charge slower, or would the power convertor draw more
power to charge the batteries.
The reason I'm asking is i have a 100 ma one and dont want ot go out and buy
200 ma one.

Can someone give me an opinion on this weather it will work safely or would
this effect the cordless phone batteries.

Others have answered correctly but a bit more explanation to add to
your understanding may be in order. If we take an example....

My old Sanyo cordless uses a 3.6V, 270mAh Ni-cd and the plug pack is
rated at 9V dc 300mA. The actual charging circuitry is contained in
the base station, as would normally be the case with other makes.
Since most cordless phones recommend that when new (or left unused for
a long time) the phone requires to be charged for about 14 hours
before use. This implies that a standard 10 hour charging rate is used
which means that in the case of my 270mAh battery it will have about
30mA pumped into it from the charger for most of the 14 hours before
it is deemed to be fully charged.

While your existing 9V supply is rated at 200mA it is a safe bet that
it would very quickly get rather warm if it were called upon to supply
more than 100mA for any length of time. These wall wart packs are
generally over-rated and they should only be expected to supply 50% of
their rated current for extended periods. Any more than that and the
output voltage tends to sag and they get hot, and this is not good. In
addition to supplying the charging current, the 9V supply also has to
supply the current required by the base unit so when when the handset
is being charged the idle current for the base unit could be around
50mA or so plus the charging current whatever that may be. Assuming a
flat battery, the combined current taken from the power pack will
probably be in the order of 100mA or so which will reduce as the
battery becomes fully charged, and this is the worst case the plug
pack will have to endure.

When the handset is in use there is obviously no charging current
required but the base unit is now going to require more current for
the transceiver operation and this could be in the order of 100mA or
more. Again, the plug pack will be supplying about half its rated
power, which over any length of extended operation is the safe maximum
for it.

Capping all this off, it is reasonable to say that a 100mA plug pack
will not be adequate for safe and reliable operation of your cordless
phone for any more than a few minutes at a time otherwise it will
almost certainly become very hot and eventually burn out. It may also
create ahazardous situation and/or damage your cordless phone.