Nokia Battery pinout

[Stan Blazejewski]

NO!

It may not be used for charging but I have 3 Nokia batteries here (BMC-3 & 2 x
BLD-3) and the readings on the center contacts change predictably according to
temperature. It could be a safety issue as my owners manual mentions the phone
may no work if it is hot (eg, left in a car).

In any case the center contacts are definately connected to a temperature
sensing device.


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[budgie]

It may not be used for charging but I have 3 Nokia batteries here (BMC-3 & 2 x
BLD-3) and the readings on the center contacts change predictably according to
temperature. It could be a safety issue as my owners manual mentions the phone
may no work if it is hot (eg, left in a car).

In any case the center contacts are definately connected to a temperature
sensing device.

Temperature is used in Li-Ion charging as a "qualifying" parameter only, not as
an end-of-charge indicator. The charge regime used almost exclusively is
current-limited constant voltage. After transition from CL to CV, charge is
usually terminated when the current has tapered off to a pre-ordained level like
10% of the CL value.

Unlike NiXX chemistries, Li-on and Li-Poly cells do not exhibit any sudden
change in terminal characteristics as they approach "full charge", and they
certainly DON'T generate any significant heat or exhibit any significant temp
rise when charged correctly.

 

[budgie]

I have looked into charging lithiums. The general practice is to hold a
constant current till the battery reaches 4.2V, then taper off the current
and hold the voltage at 4.2V till the charge current is under 10% of what it
initially started at. Then switch off. (no trickle charge)
Yup.

It would still be nice tho to find a web page of someone who has already
done something like this. I'm sure they have and I'm sure there is a web
site that describes it but its a shame that these phones and batteries are
so popular that every site I find using google is one that wants to sell me
nokia accessories!!!

I have designed a commercially available Li-Ion charger, and unfortunately they
aren't cheap if they are any good. My client tested many available units before
deciding to commission his own product, based on their unsuitability for one
reason or another.

For the record I'd prefer not to open the battery so I would still like to
know for sure what is connected to the other terminals and other specs.
including charge current etc.

It is probably either of two items: a protection module connection or a temp
sensor.

Temp is used as a charge "qualifier" (charging is inhibited if temp is too
high/low).

Protection modules are normally employed in multi-cell packs. Their roles
include over-voltage/under-voltage/over-current protection as well as monitoring
and intervening in the event of cell voltage mismatch. The latter is necessary
when a two-terminal approach is to be employed in charging/discharging a series
string of cells, as otherwise cell voltage imbalance can cause individual cells
to go under/over-voltage while the pack voltage is within spec. Because of the
safety implications of this, protection is employed.

In a single-cell application (of which cellphones are the most typical), there
is obviously no imablance issue so teh rpotection required is purely related to
charge/discharge voltage and excess current situations. It makes sense - not
always the driver of design/production though - to incorporate as much of this
circuitry as is possible in the phone rather than the (disposable) cell. So I
would not expect there to be too much of the protection system housed within the
cell package. This is particularly so as the terminals on your 3315 type phone
are fairly well protected from external contact when in the normal operating
position.

Certainly thoughtful use of a DMM would reveal good clues as to the nature of
anything connected to those extra terminals.

 

[Lord-Data]

Most nokia's equipped with "Net Monitor" hidden menus are able to display a
"temp" screen, which I believe is the reading from the batery module..

 

[the crusher]

i found that on the blb2 batt is the two midde tabs tell the phone, the
batt power levels and when to turn the phone off when the batt gets too
low.to save the batt from harm.if your phone shows one bar left then
bridge the two middle contact with tinfoil while in your phone then it
will show "full power" and work for some time (good tip if your stuck
somewhere with a flat batt).there is an unbeilveable amound of
electronics for this inside the battery.there is a temp device inside
but nothing to do with the 4 contacts it simply disconnects the minus
connection from the terminal,(which looks like it should be the plus).

 

[Heywood Jablome]

i found that on the blb2 batt is the two midde tabs tell the phone, the
batt power levels and when to turn the phone off when the batt gets too
low.to save the batt from harm.if your phone shows one bar left then
bridge the two middle contact with tinfoil while in your phone then it
will show "full power" and work for some time (good tip if your stuck
somewhere with a flat batt).there is an unbeilveable amound of
electronics for this inside the battery.there is a temp device inside
but nothing to do with the 4 contacts it simply disconnects the minus
connection from the terminal,(which looks like it should be the plus).

Thanks for that info. While these phones and batteries are very popular,
there seems to be little in the way of technical info available for the
battery.