Part Number:BQ24650
Hello Support Team,
I am using the BQ24650 to charge two Li-Ion batteries in series. I have a 20V input and a 8.35V output. When I attach the battery pack (7.9V total) the STAT1 LED turns on indicating charge in progress and then immediately turns off indicating fault. When the LED is on it pulls 6-9mA from the attached power supply. This keeps repeating until I remove the battery pack. In another scenario when I attach a battery pack that is heavily discharged (< 7V) the output voltage is still correct however the current draw is incorrect. It pulls 40mA instead of the 200mA precharge current as designed. I have taken various key measurements that I have attached below to help with diagnosis as well as my schematic of the system. The intended design is for a 17.8V MPPSET with an 8.4V & 2A output.
Any help is much appreciated.
Thanks
Also, one thing to note, the batteries are powering a system at the same time that is not indicated in the schematics.
| Measurments No Load | Measurements W/Battery Not Charging | Measurements W/Battery Charging |
| VIN = 20.1V | VIN = 20.1V | VIN = 20.1 |
| VOUT = 8.35V | VOUT =8.05V | VOUT =8.2V |
| VREF = 3.3V | VREF = 3.295V | VREF = 3.295V |
| REGN = 5.98V | REGN = 5.967V | REGN = 5.99V |
| MPPSET = 1.348V | MPPSET = 1.33V | MPPSET = 1.31V |
| TS = 2.03V | TS = 2.039V | TS = 2.039 |
| VFB = 2.1V | VFB = 2.00V | VFB = 2.03V-2.09V |
