Since there are not so many guides on battery recelling and chip reprogramming I decided to make one, hoping that it will help any beginner that is not sure how to proceed. Today I had the chance to work on a battery with a very strange combination FUJITSU battery with BQ9000 chip I have never seen this in already 7years dealing with battery repairs. So let’s find what’s wrong with this battery.

 

STEP 1 – Analyzing the battery

Connect the battery to the NLBA device and press START READING button. What we can see from the data?

1  – One of the cell groups is reading 0 volts, this is the main reason why the chip got locked.

2 – Charging Current & Charging Voltage values are 0. This can happen for a few reasons SYS pin not connected to ground /this battery does not have SYS pin/, the battery is fully charged, but in this case, RSOC is 0%, etc. So this is another indication that the chip is locked.

3 – Current is 0, and Output Led of NLBA device is OFF. Another indication that the chip is locked.

4 – If we press the BATTERY STATUS button we can see that TERMINATE CHARGE ALARM is set. This status bit can be set if the battery is FULLY CHARGED or there is a lock condition or PF /permanent fault/. In this case, since the RSOC is 0% conclusion is that the chip is locked.

 

STEP 2 – Find the fault

From STEP 1: 1  – One of the cell groups is reading 0 volts, this is the main reason why the chip got locked.

 

STEP 3 – Repair

So knowing all this there is only 1 solution. Opening the battery and replacing ALL cells and unlocking the chip.

 

 

I will not go into details on how to open a battery case etc. So after we have removed the old cells from the case we can see what was the reason for the lock condition. A short circuit because of a missing insulation pad between the positive tab and the case shell. The battery is genuine but still made by humans, and humans can make mistakes. It must be noted that not only the bottom part of the shell is negative, but the WHOLE outer shell is also negative.

 

 

Knowing that there was a short circuit we need to visually inspect the PCB for any damage. In this case, there was none, at least visually. Next, we need to identify the chip because in some cases it can happen that it is detected wrong and in this case, it was detected like a BQ8050. The reason for this is that the chip is being identified by NLBA from the static battery parameters like device name, manufacturer name etc, and the other reason is that in 2 absolutely identical batteries you can find 2 completely different chips. So the software can not be blamed if the chip is identified wrong. Actually, some other software like BE2Works don’t even have this feature so I appreciate it, and anyway, the wrong identification is a very rare thing.

 

 

STEP 4 – Check The Thermal Fuse

The next step will be to find and check the condition of the fuse. There are a few types of fuses and the test points on them are different but now I will not cover them all, we will focus on this type. We put the multimeter on continuity or /buzzer/ mode and we check between Test Point 1 & Test Point 2 you should hear a beep or a closed-circuit indication like in the picture if there is no sound or the readings are open circuit that means the fuse is blown and must be restored but only AFTER you finish with unlocking and reprograming the chip. Next we put the multimeter in resistance mode and put one probe on Test Point 3 & the other probe on Test Point 1 or 2, and depending on the fuse model you will see resistance from around 10 to 50ohms. This is the resistance of the heating element that melts the fuse. So we can confirm that the fuse is ok.