Step 2: Use a multi-meter to measure their charged voltage (If it rapidly drops from 3.6v, they are bad).

Step 3: If the voltage stays good, discharge the cells through a load (500mA for regular 18650 cells) and watch their voltage. Make sure they are not dropping too fast. (I’d expect a good 18650 cell to last for at least 10 minutes without a big voltage drop when discharging 500 mA). [The "cheating" way to do this is to use the multi-meter in current sensing mode, and discharge the cell into the multi-meter. This is dangerous as you could potentially cause the cell to overheat and burn. But it does keep you from having to find a good 500mA load ;>. If they provide a good amount of power for several seconds it usually means that the cells are not completely bad.]

Jay

Jay

can describe how u pry open the battery casing??? i have got a dead Lenovo N100 batt tat needs some rescue work… but i cant seem to be able to see any clips from the casing.. pls kindly advice. thank u

A bit of my history…
I worked in Telecommunications for 27 years..
I repair computers for a sideline…I am semi-retired.

Computer is a Compaq Presario R3000.
The original battery is a HSTNN-UB02 (4400MAH)

Using the old battery,the laptop charge light came on and went out ever so quickly on power-up. With the battery removed, (or in), the laptop works very well on AC.

SO…
I took the battery apart…and found 2 of the 8 CR18650 cells to be very dead. (and would overheat rapidly if I connected the 14.8 volt string to a car battery charger). The rest would begin charging…

I made a simple diagram to aid in the rebuilding. This is a battery comprised of 4 sets in series of 3 CR18650′s in parallel…(3.7 volts) x 4 = 14.8 volts. I was constructing a 2800×3 = 8400MAH battery…WOOOO, the reserve!!!

SO…
I replaced all of the cells with 12 (filled in the blank spaces) 2800 MAH CR18650 cells bought from E=Bay.

The wiring was simple enough…space was a bit of a problem, but I got it all nicely in the case.
I temporarily taped the case together….to try it in the laptop…and VOILA!!!

Nothing.
Nada.
Zippo.

When I plug the battery in to the computer, it does recognize that a battery is there; it just isn’t charging.
With the battery OUT of the laptop, there is NOT 14.8 volts (or a resonable amount) on any of the pins.
There IS 14.8 volts going in on the B+ pin on the protection circuit board.

SO…I read my face off…and lo and behold, discover that the small PCB in the battery case is not merely a voltage regulator, or charge controller, or anything else I had imagined it to be.
It does contain an EEPROM, and other circuits:

Renesas M61047FP Battery Protection Analog Front End (AFE) IC
M37517 Microprocessor…( marked thusly): M37517
F8024
3511a
SO…
Since my battery is outputting zero, I now have to assume that either the protection circuit board is duff, or that the EEPROM needs to be reset back to the original values.

I do NOT know the pinout of the HSTNN-UB02 Battery…it would help if I did, because then I’d know what the pins on the battery are as well.

I have the datasheet for the M61047FP Battery Protection circuit.
I could include it here, if anyone can help determine how to reset this thing from what was essentially, a power-down mode. The datasheet simply says that once a charger is detected by the circuit, a reset is sent to the microprocessor to get things back to “normal”.

I also see that there are a few software programs out there that will “reset the EEPROM”, but the one I looked at was a mere $179…….

Any ideas? Any help would be appreciated….largely!!!

I have got a compaq 6604au notebook and its about 18 months old and since two weeks my battery started acting quite weird. My battery meter indicates that the battery is charging but still stuck at 39%. Whatever i try it won’t go above that.But sometimes it suddenly goes to 100% for a few seconds and again drops to 39% in less than a 30secs even if its on AC power.

I have even tried calibrating the battery but that didn’t work either.

What do you think i should do about this?

The 2nd picture down shows how the battery splits into two:
http://www.summet.com/blog/wp-content/uploads/2007/02/li-cells.jpg
Jay

I wanted to replace my IBM X31 battery but I don’t exactly know where’s the seam that you’ve mentioned. Do you have a picture to show? Thanks!

I bought my Li-Ion cells at Batteryspace.com. They also sell li-po cells (which are easier to fit into small square/flat packages).

People use li-pro mostly for the ability to mold/form them into non cylindrical shapes, but they are a slightly different battery chemistry as well.

You should be able to substitute Li-Ion for Li-Po cells or visa versa as long as you are able to get them to fit in the enclosure.

Jay