On 21/06/2011 19:04, John Rumm wrote:
On 21/06/2011 17:23, Gareth wrote:

On 21/06/2011 13:41, Theo Markettos wrote:
wrote:
John wrote:
One option:

Remove batter and look at the marked voltage.
Set bench PSU to same
Connect PSU to battery terminals on phone...

Bench PSU? Whats wrong with two flyleads from the phone charger?

The phone charger input is likely at a different voltage to the
natural cell
voltage of the battery (eg 5V from USB v 3.6V from lithium ion). The
battery charge circuit might not like that.

As it is, you might still have difficulty: the battery smarts won't be
there. Depends whether the phone will power up if it has a voltage but
can't read status from the battery.

Theo

Phone batteries are not *usually* that smart - they usually have a
simple analogue circuit which will disconnect the battery to prevent
overcharge or overcurrent. The third terminal is usually a thermistor
connected to the negative terminal which the charging circuit in the
phone uses to monitor battery temperature.

I have successfully charged phone batteries from a bench PSU.

Yup, BTDTGTTS. The nice posh farnell ones with current limiter are good
for this - just set that to 100mA or similar and hook it up - no need to
be too fussy with the voltage that way.


I would recommend setting the voltage carefully for a lithium ion
battery as they can fail spectacularly, see the explosion 2 minutes into
this video:

http://www.youtube.com/watch?v=SMy2_...eature=related

The maximum voltage for a single cell is 4.2V.

Any commercial battery will probably have a protection module to prevent
over voltage so you would almost certainly get away it if you did set
the voltage a bit too high but all the datasheets I have seen recommend
that you don't rely on the protection module for for charge termination.

Gareth