We have created a new design based on the BQ24125 that is used to charge a 3S LiPo.
Before adding the circuitry to the design we modified the resistors on an EVK to set the feedback for the 3S battery.
The first EVK we purchased seemed to have a short so we bought a new one and it appear to work properly so we designed it in.
The first article of the new board seemed to have the same issue as the original EVK but the second one did not. I am reluctant to power more before root causing this issue.
Here is a snapshot of the design:
Furthermore, we were experimenting with the thermal shutdown feature on the second EVK and after a number of power cycles the board it started failing as well.
We bought a third EVK and it fail after only a few power cycles.
When the failure occurs that charger is presenting around 14V on the battery terminals when the battery is not connected.
When the battery is installed it overcurrents and triggers the supply to drop out. Kind of expected since 14V is too high for a 3S battery.
Is there an explanation for the chargers to be failing in this manner? On the EVK we are only changing the setpoints on FB and TS.
When the failure occurs the battery voltage appears to be slightly below to input voltage. Like a diode drop away.
Could it be an ESD issue? Surge from the power supply?
Any recommendations would be greatly appreciated. If this is not resolved soon we may have to design in a new charger.
Anything that can prevent this? Protection diodes?
When powering new board, I have been powering the charger without the battery in place to see if the appropriate current and battery searching signature are there before installing a battery.
