Ericsson A2618s mobile phone - charging flat battery

[Franc Zabkar]

I recently purchased two new Ericsson A2618s mobile phones that may
have been sitting on the shelf for up to a year. Needless to say, the
3.6V 750mAh NiMH battery packs (p/n BSC-11) had expired on the shelf
and were measuring only 2.0V. An overnight charge failed to recover
either battery pack. Further investigation revealed that neither phone
had made an attempt to charge these expired batteries, which suggests
to me that the A2618s has an intelligent charging system that avoids
batteries which it considers to be dead. After verifying that both
phones and both chargers would correctly charge a known good battery
pack, I returned the phones and batteries to Ericsson's service rep
(Fonebiz). Some three weeks later I received two replacement
batteries, still in their sealed packages. Unfortunately, these too
were old stock (2.0V) and once again failed to charge. :-( This time I
constructed a jig out of an old cable harness, a 39 ohm series
resistor, and a regulated 4.5VDC supply. After charging for a few
hours, I installed the battery packs in the phones and was rewarded
with proper charging behaviour. Unfortunately I have since discovered
that even after several charge/discharge cycles, neither battery pack
approaches the claimed 110 hour standby capacity. The closest is
around 40 hours.

Am I correct in assuming that the phone's charging system analyses the
state of the battery and refuses to charge it if its voltage is too
low? Ericsson customer service was unable to answer this question.

The battery packs have three pins, red (+), black (-), and blue. The
blue and black wires appear to be tied together. Does anyone know the
function of the blue wire? Is it used to differentiate between NiMH
packs amd Li-Ion packs (p/n BHC-11)? Does it connect to a thermal
cutout?


- Franc Zabkar

 

[Jerry G.]

You will need to have fresh batteries. It is possible that after a number
of charge cycles, the batteries may equalize back to normal. We have many
cell phones in our facility. We found that even with a new battery, the
operating time is not peaked until about the 5th charge cycle. It is best to
run the battery to near flat and then recharge it back again if you want to
really deep cycle it. Once this is done, then it should work normal for its
lifespan. Use only the designed charger for the battery. It analyses the
battery condition and adjusts itself by sensing the current pull.

There is usually a 3rd contact on these batteries. This is for thermo
sensing. If the battery is overheated, the thermo will open up, thus
shutting the charge to the battery. This is to prevent the battery from
erupting, causing damage, and chemical spill. Some of these batteries have a
built in microprocessor board, that has a program in it to match to the
particular batteries within.

These computer type charging systems keeps track of the battery condition,
and makes sure that the charger is charging at the optimum rate. If one of
the cells in the battery pack goes defective, then the controller will abort
and indicate that the battery is defective. This is the norm when this type
of sensing technology is used.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
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Electronics http://www.zoom-one.com/electron.htm
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I recently purchased two new Ericsson A2618s mobile phones that may
have been sitting on the shelf for up to a year. Needless to say, the
3.6V 750mAh NiMH battery packs (p/n BSC-11) had expired on the shelf
and were measuring only 2.0V. An overnight charge failed to recover
either battery pack. Further investigation revealed that neither phone
had made an attempt to charge these expired batteries, which suggests
to me that the A2618s has an intelligent charging system that avoids
batteries which it considers to be dead. After verifying that both
phones and both chargers would correctly charge a known good battery
pack, I returned the phones and batteries to Ericsson's service rep
(Fonebiz). Some three weeks later I received two replacement
batteries, still in their sealed packages. Unfortunately, these too
were old stock (2.0V) and once again failed to charge. :-( This time I
constructed a jig out of an old cable harness, a 39 ohm series
resistor, and a regulated 4.5VDC supply. After charging for a few
hours, I installed the battery packs in the phones and was rewarded
with proper charging behaviour. Unfortunately I have since discovered
that even after several charge/discharge cycles, neither battery pack
approaches the claimed 110 hour standby capacity. The closest is
around 40 hours.

Am I correct in assuming that the phone's charging system analyses the
state of the battery and refuses to charge it if its voltage is too
low? Ericsson customer service was unable to answer this question.

The battery packs have three pins, red (+), black (-), and blue. The
blue and black wires appear to be tied together. Does anyone know the
function of the blue wire? Is it used to differentiate between NiMH
packs amd Li-Ion packs (p/n BHC-11)? Does it connect to a thermal
cutout?


- Franc Zabkar

 

[Andre]

You will need to have fresh batteries. It is possible that after a number
of charge cycles, the batteries may equalize back to normal. We have many
cell phones in our facility. We found that even with a new battery, the
operating time is not peaked until about the 5th charge cycle. It is best to
run the battery to near flat and then recharge it back again if you want to
really deep cycle it. Once this is done, then it should work normal for its
lifespan. Use only the designed charger for the battery. It analyses the
battery condition and adjusts itself by sensing the current pull.

Hmm - I've revived them by slowly charging over 48 hours from a really
low constant current.