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Repair LI-ION battery pack (Gallopwire)

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2PAC Mafia

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Hello,

I opened two broken battery packs from two different laptops, one is an Airis I had but is broken so I don´t really need to repair it but the other is a battery pack from my actual laptop which I want to repair.

The price of this pack is around 180€ and the life was very short. As I use mainly the laptop in my office I protected always the pins of the battery to avoid the charge of the battery too often and I thought like that I could extend its life, but one day when I wanted to charge it didn´t work.

The new one I have I always charge and discharge it fully to have it always working. The model is 8880 DC 14.8V 6000mAH.

The failure is that it doesn´t take any charge, like it was interrupted and I would know if somebody knows to repair this packs or has a drawing of the small PCB and pins. I guess the problem is on the PCB, I don´t think it is on the rechargeable batteries, don´t you?

The only think I could check was a thermal fuse which is OK.

Thanks.
 
Hiya 2pac,
Generally only 1 or 2 cells in a laptop battery go bad and the rest are still good. Awhile ago I got 3 laptop batteries that had gone bad from a puter repair shop. I found the only way to get them apart was rip the case apart. On all 3 only 2 cells had gone in each of them so now I use the indivudual cells in my electronic projects and charge them via my ultra smart battery charger I made. Maybe if you could pry the cases apart carefully with a utility knife and find the dead cells you could make 1 good battery out of them. To solder the batteries you need to sand a small area with some sandpaper first or the solder won't stick.

Best of Luck

Cheers Bryan :D
 
Hello Bryan,

thanks for the info, my battery pack has 12 cells interconnected, 8 pins as inputs/outputs at PCB and 5 cables connecting the PCB at different points on the cells.

How do you check the cells individually to find out which one is failing, do you measure voltage, resistence, current...?
 
2PAC Mafia said:
How do you check the cells individually to find out which one is failing, do you measure voltage, resistence, current...?

You basically measure voltage, you may be lucky and simple voltage measurement may present you with obvious faulty cells. If not, you may need to charge them up and apply a load while monitoring the voltages per cell.
 
Hello,

ok, the cells are ICR18650W2 and they are connected as follows:

4 blocks in series and each block has three cells in parallel for a total of 12 cells. At each step there is a cable connected to the PCB I guess for monitoring the voltage so, there is a red cable at the main plus, orange cable at the next negative-plus, white cable at the next negative-plus, blue cable at the next and finally the black cable at negative followed by the thermal fuse. All the cables go to the PCB.

Then from the PCB there are 8 pins for outside. I have test the voltage but it´s nearly empty so now my doubt is find out the way to connect charge voltage at the pack:

A) Should I connect DC voltage between main plus and main negative at cells or should I do it at outside pins? I don´t know the function of each pin...

B) Which voltage should I supply at those cables? The battery says DC 14.6V 6000mAH and the charger from the laptop 20Vdc 6A... so I guess I should supply 20Vdc 6A

C) The battery charger plug for the laptop has 4 pins, do you think those 20V are going directly to the battery pack?
 
2PAC Mafia said:
B) Which voltage should I supply at those cables? The battery says DC 14.6V 6000mAH and the charger from the laptop 20Vdc 6A... so I guess I should supply 20Vdc 6A

The laptop will include charging circuitry for the batteries, you can't just stick the laptops PSU directly on them. Use a current limiting resistor, and charge them gently - if the batteries are rated at 6A, then calculate the resistor for about 600mA.
 
What battery type are we talking about? Li-ion or NiMH?

Li-ion is relatively complicated to charge, and they are easily damaged by overcharge. NiMH is somewhat simpler and more durable.
 
Hello,

The laptop will include charging circuitry for the batteries, you can't just stick the laptops PSU directly on them. Use a current limiting resistor, and charge them gently - if the batteries are rated at 6A, then calculate the resistor for about 600mA.

I have a 0-30V / 10A power supply where I also can limit the current, I will use that one...

What battery type are we talking about? Li-ion or NiMH?

Li-ion is relatively complicated to charge, and they are easily damaged by overcharge. NiMH is somewhat simpler and more durable.

It´s LI-ION battery, any recommendation to charge it?
 
Battery Charging

I don't think it would be a good idea to charge your battery pack from the power supply you have in the absence of either constant monitoring of current and voltage and cell temperature or a dedicated Li-Ion charger IC. These batteries can be damaged by charging above a specific voltage per cell, independent of charging current. Nicads can tolerate overcharging at a modest current after they are fully charged because the evolved gasses can be recombined withing the cell, provided the rate of production of the gasses is not so high that cell pressure builds up excessively. If that happens, the cells vent and lose materials permanantly.

Li-Ion batteries do not have this tolerance and will be damaged by overcharging. It is definitely not a good idea to intend to observe voltage, current, and temperature and manually control the system because sooner or later (probably very soon) you will be distracted and the battery will be permanently damaged.

Study the spec sheets for Li-Ion battery charger ICs from Maxim and others and get charging info from Li-Ion battery manufacturers. Maxim is really good at offering samples of their ICs, and have demonstration circuit boards for many of their ICs. Give them a try.

awright
 
Hello Awright,

a good option would be to know the function of each pin input I have at the PCB of the battery pack which connect at the Laptop pins, but I don´t have that info. Then I think the laptop supplies the constant voltage and the demand depends on the control of the battery PCB...

Anyway I will look for Li-Ion battery charge properties, thanks for the info.
 
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