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Li-Poly battery connections....

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Full Member level 5
Oct 30, 2005
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I have a phone battery, its PQT001 actually.

Anyway, so there is 6 terminals. The battery is fully charged.

with voltmeter I get 3.7volts at one terminal, and 0V at 4 others.
Ok I thought beauty can easily test also with a blue led.
surprise, it doesn't light.
Measure the voltage, it drops to 2.2 volts when led connected,
does not matter which combination of 0V terminals.

so I'm thinking maybe its internal protection, so does anyone understand
how that might work ?

If I could find a datasheet on the battery that would be good, but no luck yet....
or any mobile phone battery would be good, for tips. But I'm not finding
any like datasheets for batteries! why?

I want to be able to charge the battery from a small solar panel (when going hiking)
hence investigating direct connection to battery .... as it would fit for the little solar
panel I got.

so I am stuck at the moment....

---------- Post added at 14:51 ---------- Previous post was at 13:24 ----------

might have worked it out

1 2 3 4 5 6

1&2 are same (measure 1R)
3 measure 3.7V
4 not sure,but I would bet its a connection to thermistor
5&6 are same (like 1&2)

so I put a 68R resistor btw 1&2 -> 3
ammeter + to 1&2 - to 68R to 5&6

get 70mA
and 4V btw 1&2 (+) and 5&6(-)

wonder if resistor 68R btw 1&2 -> 3 can be shorted.......

used 68R only 'cus thats what I had in front of me at the time........

When use blue led, but no resistor to limited current, the volatge in battery V+ will drop fast , then the battery will in protection status.

Do you could charge the battery voltage up again ?

Most mobile phone batteries have a 3-pin connector and a thermistor to sense charging temperature. In addition they have a kind of fuse to protect against fire in case of fatal shorts. Charging of mobile phone batteries has to be controlled externally.

I don't assume, that your 6-pin connector exposes additional functionality. You can try to get a schematic diagram of the phone.

"Intelligent" multi-cell batteries (e.g. for notebook computers) have charge controllers balancing the cell voltage and protecting the battery against deep discharge and overcharge. They expose an SMBUS (i2C variant) interface.

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