BQ40Z50-R1: Charging/ Discharging too fast causes the battery to stop working.

Abdullah Zaman

Part Number: BQ40Z50-R1

I have a LiFePO4 7.8Ah/ 12.8V/ 99.84Wh battery. Which has a stm8 controller and the BMS chip BQ40Z50-R1.

First off If I use the battery standalone (without the charger there are no issues).

The problem I have occurs only when I have battery connected with charger and using the battery to draw maximum current. It seems that the charging and discharging together at max output causes the bms to detect Cell Over Voltage (COV) failure and stops the battery to work. To get the battery to work again I have to restart the battery or clear the failure using the Battery Management Studio.

Is there any way I can figure out what is the trigger point for this failure? Or can I setup a threshold so that if battery is discharging at max stop charging.

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi Abdullah,

Take a look at Section 2.4 Cell Overvoltage Protection of BQ40z50-R1 TRM. You will see the conditions that trigger the COV protection.

Andy

0 Abdullah Zaman over 5 years ago in reply to Andy Liu (BMS)

Prodigy 70 points

Hi Andy,

I can see the case when COV gets triggered and then leads to SOV permanent failure. Can you please let me know how I can determine what the correct parameters should be for the BMS e.g (max voltage threshold) Is there any documentation for that or should I refer to the cells manual?

I think the BMS parameters are default as of know and could cause the battery to trip even if it is nominal.

0 Kang Kang over 5 years ago in reply to Abdullah Zaman

TI__Mastermind 24870 points

Hello Abdullah,

This actually depends on your system. I recommend reading the TRM to understand this feature and then asking us more specifically with your system information on where you want COV to trip.

Power management

Power management forum

BQ40Z50-R1: Charging/ Discharging too fast causes the battery to stop working.