Should I obey my phone's charging advice?

[David Segall]

My mobile phone, an Android based Samsung Galaxy SII, nags me to
unplug the charger as soon as it is fully charged. A couple of my
chargers state specifically that they are "intelligent" but the phone
does not seem to distinguish them.

In addition, I have a stand that includes a slot and charger for a
spare battery but no advice about the state of charge.

What level of harm will result if I often leave a charged battery on
the charger overnight? What about for a few months?

TIA, David.

 

[Sylvia Else]

On 28/10/2011 11:49 PM, David Segall wrote:

My mobile phone, an Android based Samsung Galaxy SII, nags me to
unplug the charger as soon as it is fully charged. A couple of my
chargers state specifically that they are "intelligent" but the phone
does not seem to distinguish them.

Which rather begs the question of what it is that the "intelligent"
charger claims to do. If it ceases supplying current, then one wonders
how the phone knows that it's still connected. I suppose the phone might
have a switch in the socket, but that seems a bit crude.

Does the phone consider the charger is connected if the charger itself
is unplugged from the mains?

Sylvia.

 

[Peter]

Sylvia Else wrote:

On 28/10/2011 11:49 PM, David Segall wrote:
My mobile phone, an Android based Samsung Galaxy SII, nags me to
unplug the charger as soon as it is fully charged. A couple of my
chargers state specifically that they are "intelligent" but the phone
does not seem to distinguish them.

Which rather begs the question of what it is that the "intelligent"
charger claims to do. If it ceases supplying current, then one wonders
how the phone knows that it's still connected. I suppose the phone might
have a switch in the socket, but that seems a bit crude.

Does the phone consider the charger is connected if the charger itself
is unplugged from the mains?

Nowdays, the charging circuitry is almost always in the phone, not the
plug pack, which is just a power supply.

Peter

 

[John Tserkezis]

Peter wrote:

Nowdays, the charging circuitry is almost always in the phone, not the
plug pack, which is just a power supply.

I'm nitpicking here, but the charging circuitry (if the phone has a
removable battery) the charging circuit is within the battery itself.

If you have a phone with a non user-replaceable battery, then aside
from being a mug, the charging circuitry is then part of the phone
mainboard (it saves cost that way).

To the original poster:
It is *safe* to leave the phone plugged into the charger (or cradle as
the case may be), regardless of who tells you what.

The only "problem" you might have by leaving the device on power the
whole time is the battery doesn't get exercised (charged - used -
charged - used etc).

This advice probably doesn't apply to mobile phones, as well, they're
*mobile* and you have to unplug them to use them, but applies more to
laptops that are only ever used as desktops, and never unplugged.

Use it or lose it as the saying goes, if you don't exercise the
battery, some time down the track when you DO need it, it simply won't
last as long as you would hope.



If you're paranoid and you have a regular regulated DC charger
plug-pack, you can monitor the current. While not charging, there will
be some residule current that powers the phone, (and that varies a bit
depending on if the phone radio is communicating or not) but most of the
time it will be steady.
When charging, you'll see the steady current rise until the battery is
full, then drop to the normal steady current.

The usual course of action, is (with lithium rechargables) is when
first applying the phone to the charger, it looks at the condition of
charge (there's circuitry in there for that), and for anything above
about 80% it won't do anything.
Below that, it starts charging as per normal.

NiMH and NiCads are different, when first applying the charger, it
will attempt to charge, then turn off when the circuitry realises it's
charged.
In this case, there is a risk if you sit there and continually
charge/remove/charge/remove the device, it will force a bit of charge
every time you do that, and risk over charging.
Later on, there were indeed some NiMH/NiCad circuitry that worked as
above, and did NOT start charging until it was clear the battery was NOT
fully charged first.
--
What do you feed a Trojan horse? A latex lollipop!

 

[who where]

On Fri, 28 Oct 2011 23:49:34 +1100, David Segall
<david@address.invalid> wrote:

My mobile phone, an Android based Samsung Galaxy SII, nags me to
unplug the charger as soon as it is fully charged. A couple of my
chargers state specifically that they are "intelligent" but the phone
does not seem to distinguish them.

In addition, I have a stand that includes a slot and charger for a
spare battery but no advice about the state of charge.

What level of harm will result if I often leave a charged battery on
the charger overnight? What about for a few months?

If it is a Li-xx chemistry (which is almost beyond doubt in anything
of this century, and even more so of anything vaguely current) then it
will cause no harm whatsoever.

 

[who where]

On Sat, 29 Oct 2011 13:47:32 +1100, John Tserkezis
<jt@techniciansyndrome.org.invalid> wrote:

Peter wrote:

Nowdays, the charging circuitry is almost always in the phone, not the
plug pack, which is just a power supply.

I'm nitpicking here, but the charging circuitry (if the phone has a
removable battery) the charging circuit is within the battery itself.

I would beg to differ, The battery (which a nitpicker would not have
called a battery anyway, as it techiocally isn't ...) contains a
protection module, but the charge regime is managed by circuitry in
the phone in all the examples I have seen. This can be demonstrated
by attaching a random lithium-ion or lithium-polymer cell (and
appropriate presence/thermal bridging) to a phone's cell connections,
where the cell will properly charge.

If you have a phone with a non user-replaceable battery, then aside
from being a mug, the charging circuitry is then part of the phone
mainboard (it saves cost that way).

It is there too.

To the original poster:
It is *safe* to leave the phone plugged into the charger (or cradle as
the case may be), regardless of who tells you what.

The only "problem" you might have by leaving the device on power the
whole time is the battery doesn't get exercised (charged - used -
charged - used etc).

Exercising is not necessary in the slightest for lithium-based cells,
as there is no memory effect. The only downside of leaving them
connected to a charger long-term is that the cell voltage will remain
at the upper end of the working range. There are three things which
cause degradation of these cells:

.. time
.. elevated tempreature
.. elevated terminal voltage.

As phone manufacturers want to wring the maximum run-time out of them,
they are likely to use a reasonably aggressive selection of charge
termination voltage. But as (apparently) most users of latest-tech
mobile phones seem to replace them at every contract period expiry,
the difference is not likely to be significant.

This advice probably doesn't apply to mobile phones, as well, they're
*mobile* and you have to unplug them to use them, but applies more to
laptops that are only ever used as desktops, and never unplugged.

Use it or lose it as the saying goes, if you don't exercise the
battery, some time down the track when you DO need it, it simply won't
last as long as you would hope.

Minimal difference.

If you're paranoid and you have a regular regulated DC charger
plug-pack, you can monitor the current. While not charging, there will
be some residule current that powers the phone, (and that varies a bit
depending on if the phone radio is communicating or not) but most of the
time it will be steady.
When charging, you'll see the steady current rise until the battery is
full, then drop to the normal steady current.

The usual course of action, is (with lithium rechargables) is when
first applying the phone to the charger, it looks at the condition of
charge (there's circuitry in there for that), and for anything above
about 80% it won't do anything.
Below that, it starts charging as per normal.

NiMH and NiCads are different, when first applying the charger, it
will attempt to charge, then turn off when the circuitry realises it's
charged.
In this case, there is a risk if you sit there and continually
charge/remove/charge/remove the device, it will force a bit of charge
every time you do that, and risk over charging.
Later on, there were indeed some NiMH/NiCad circuitry that worked as
above, and did NOT start charging until it was clear the battery was NOT
fully charged first.

 

[David Segall]

Sylvia Else <sylvia@not.here.invalid> wrote:

On 28/10/2011 11:49 PM, David Segall wrote:
My mobile phone, an Android based Samsung Galaxy SII, nags me to
unplug the charger as soon as it is fully charged. A couple of my
chargers state specifically that they are "intelligent" but the phone
does not seem to distinguish them.

Which rather begs the question of what it is that the "intelligent"
charger claims to do. If it ceases supplying current, then one wonders
how the phone knows that it's still connected. I suppose the phone might
have a switch in the socket, but that seems a bit crude.

Does the phone consider the charger is connected if the charger itself
is unplugged from the mains?

The phone changes its battery saving mode regardless of whether I
unplug it from the mains or the charger.