BQ24650: Battery Charger goes to fault state and stops charging

Part Number: BQ24650


We have designed our circuit based on BQ24650RVAR reference design. I have attached my charging circuit design. I Have pulled the Term_EN pin to ground so that solar supply continue to operate as buck converter for the load which is around 150mA@12V when solar input is available in order to avoid any battery discharge when sunshine is available. We are using lead acid battery(2.5AH). I have attached spec of my solar panel. We are finding that when the battery voltage reaches around 11.5V, there is steep discharge in the battery voltage which leads to discharge up to 4-5V in very small interval(less than 30min). It goes to deep discharge. Sometimes even if sun is available, battery discharges as battery charger doesn't supply current. During this time, charger goes to fault state. we could see that both Stat1 and Stat2 pins get high(led gets off).

Initially we thought it maybe problem with the solar panel(10W) that current supplied may not be enough for both battery charging and around 120mA load. so we tested with higher capacity(18W) solar panel which i have attached spec. We have observed that once the charger goes to fault state, it remains in fault state and doesn't overcome until the charger is power resetted. After it is power resetted, it regains supplying current to battery and load.

We have tested it on 5units and all units behaved the similar behavior.

  • I want to know what are the fault states in this charger and how charger can recover from fault state.
  • in what condition, charger can go to fault state.
  • in what condition, it can come out of fault state.



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