As far as i remember there was a topic here in the forum where a user was trying to replace LIHV 4.35v cells with standart 4.2v cells on a BQ30XXX chip and the Stage Of Charge was reported wrong which is normal since the discharge curve and chemical characteristics of the cells were different. The purpose of this tutorial will be to show users how this problem can be solved. It requires chip dataflash reprograming via additional hardware (EV2300 adapter) and additional software BQEvsw. There are a few main reasons why we can’t replace 4.35v cells with 4.2v.

1. 4.2v cells will die very fast due to overcharging since they are designed to be charged to 4.2v maximum.
2. Most of the times LIHV 4.35v cells will have a high discharge cut off voltage that is written in the firmware (EMF). The chip will consider the battery as empty when voltages of cells reach around 3.5-3.4v since discharging further will result in a very unstable and fast voltage drop. A normal 4.2v cell will not be able to deliver it’s full potential until 3.5-3.4v and it needs to be discharged to at least 3.1-3.0v.
3. 4.35v LIHV cells are very hard to find and are very expensive.

So it should be clear by now why dataflash reprograming needs to take place. And before we even start I will post the original cells discharge curve so it can be compared to new cells discharge curve that I will use so you can see the difference.

The original cells were LGABC11865

The new replacement cells are LGGBH261865

STEP 1   Analyzing

We start with the initial first read of the battery with NLBA. We can see that it’s still unlocked and working fine but FCC has dropped below 50% which is normal considering that the cells have 236 cycles. We can also see that the chip is detected as BQ30421 which is correct. The Charging Voltage is 13050mv and the battery is 3s 2p so if we do the simple math  ( 13050mv ÷ 3s = 4350mv).

STEP 2   Unsealing the chip so dataflash can be read and edited

Probably the most important step since if the chip is not unsealed reading and editing dataflash content is impossible! NLBA handles the unsealing process gracefully within a few seconds. No problems at all.

1. To verify that the chip is sealed press READ CHIP INFO button.
2. To Unseal press UNSEAL/BOOT button.
3. To verify that chip is unsealed press READ CHIP INFO button again.
4. DO NOT press END RESET button or the chip will be sealed again. Just disconnect the battery from NLBA and connect it to EV2300.

Step 3    Reprograming the dataflash using EV2300 & BQEvsw

So the battery is already transferred and connected EV2300 & BQEvsw.

We press the refresh button so initial dynamic data can be read.

Next we press DATA FLASH button followed by READ ALL button and this will result in displaying the whole dataflash content.

On PAGE 1  change the following values.

Remaining Cap Alarm = 10% of Desing Capacity

Manufacture Date = Current Date in hex

Cycle Count = 0

Design Capacity = Your new cells capacity

Full Charge Capacity = Design Capacity

Charging Voltage = 12600 ( 3S 2P BATTERY)

On PAGE 2  change the following values.

Safety Voltage = 12900

Emf = 3500

On PAGE 3  change the following values.

Vcell Unbalance Threshold – this is optional, it’s the cells imbalance value that will cause the chip to lock if greater then programed. In this case it’s 300mv which is a little low so it will be increased to 500mv.

Vmax Charge Voltage = 4260

Voff Charge Voltage   = 4260

Von Charge Voltage   = 4250

On PAGE 4  change the following values.

CCCV Charging Voltage = 12600

CCCV Over Voltage = 4250

CCCV Over Voltage Reset = 4150

CCCV Chg Voltage Cold = 12600

CCCV Chg Voltage Hot = 12600

Pulse Chg Voltage Cold = 12600

Pulse Chg Voltage Hot = 12600

On PAGE 5  change the following values.

Cccv Charge Volt cool warm = 12600

Pulse Charge Volt Cool Warm= 12600

Hot Charge Voltage = 12600

Hot Charge Voltage 2 = 4200

Weak FC Voltage = 4200

Sprint Max Chg Volt = 12600

Intvl Chg Min Chg Voltage =  12600

So we are done with dataflash reprograming. We just need to press WRITE ALL button to save all the settings. After we save the settings we can transfer the battery back to NLBA so we can check all the results.

Step 4 FINAL RESULT

So as we can see all the changes we have made are reflected in the dynamic & static data already.

The dataflash has been reprogrammed properly and the battery will work normally with 4.2v cells.