Repair of a portable computer battery pack

Hi, I'm writing from a Gericom Webshox portable computer of 2001, now the battery pack ( UN241S1 Rechargeable Li-Ion Battery Ratings:

14,4Vdc 3600mAh ) is broken son I decide to change the accumulators, I choose 8 NiMH 3,6Ah 1,2V Accumulator.

After the substitution it still doesn't work, the charge seems to be ok, also is I do not understand why is used a 14 Volt supply to charge battery pack to about 5,8V


  • +

- - ------------------white

  • +

- - ------------------yellow

  • +

- - ------------------green

  • +

- - ------------------black

The discharge phase is not ok, the 5,8v coming from the accumulators seems to be blocked in one of the two printed circuits comprised in the battery pack, so my questions:

1) What is the job of these two circuits?

2) It is possible to connect directly the accumulators to the output bypassing these circuits?

3) What the white, yellow and green wires are used for??

4) where I can found a scheme of a typical battery pack ??

5) why the supply is 14v to charge a 5,8v battery pack ??

Hoping in your help

many thanks ...

Antonio D'Ottavio

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1) Li cells need constant voltage charging. NiMH cells need constant current charging.

2) 8 x 1.2V = 9.6V compared to 14.4V provided by the Li cells

You may well have damaged the charger and or battery by using the wrong type of charger.

WARNING: What you have done may cause a fire risk.

No it doesn't.

Could be...

a) To control the charge cycle (eg To stop overcharge and fire) b) To control the discharge cycle (eg to stop overdischarge and battery damage or fire) c) Provide a charge level meter to the laptop..

Yes, no or maybe.

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I should clarify that a bit...

At the start of the charge cycle they need constant current and once the voltage rises they need constant voltage.

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