BQ24630: STAT1 is on without battery connected, but does not charge

Sankar Manoj

Part Number: BQ24630

The circuit is designed for a 6 cell LiFePO4 battery, with ISET1 at 6A, ACSET at 7.85A, and ISET2 at 0.6A.

When I plug in the AC power, without the battery connected, the STAT1 LED glows. We have added a total of 20uF capacitors across the battery terminal. When I connect the battery, the STAT1 LED still glows, however, no actual charging takes place. The voltage measured across the battery terminals doesn't increase.

over 3 years ago

0 Michael Emanuel35 over 3 years ago

TI__Mastermind 35135 points

Hello,

Can you please share your schematic, as well as your input voltage, battery voltage, and TS voltage when this is happening?

Thanks,

Mike Emanuel

0 Sankar Manoj over 3 years ago in reply to Michael Emanuel35

Prodigy 10 points

Input Voltage = 24.2 V
Battery Voltage = 18.7V
TS = 2.2V
ISET1 = 1.1V
ISET2 = 0.6V
ACSET = 1.5V
All CSRs = 0.01 ohm

0 Michael Emanuel35 over 3 years ago in reply to Sankar Manoj

TI__Mastermind 35135 points

Can you also share some waveforms of the input voltage, output voltage, PH voltage, and charge current?

Thanks,

Mike Emanuel

0 Sankar Manoj over 3 years ago in reply to Michael Emanuel35

Prodigy 10 points

Hi Mike,

0 Sankar Manoj over 3 years ago in reply to Sankar Manoj

Prodigy 10 points

Hi Mike,

I've changed the battery to a 4S LiFePO4 battery. That is why the battery output voltage is lower than what I had mentioned earlier.

I noticed that the capacitor between PH and BTST does not get charged. I measured the resistance across these two points, and it's around 6 Ohm when the IC is powered on from AC.

Another thing I noticed is that PH and HIDRV have the exact same voltage, and so the VGS for the HIDRV MOSFET is 0V and so the battery does not charge.

Regards,

Sankar

0 Michael Emanuel35 over 3 years ago in reply to Sankar Manoj

TI__Mastermind 35135 points

Dear Sankar,

What is the input voltage and the battery voltage now?

Have you verified your layout to make sure that there is not a short between PH, BTST, and/or HIDRV?

Thanks,

Mike Emanuel

0 Sankar Manoj over 3 years ago in reply to Michael Emanuel35

Prodigy 10 points

Hi Mike.

My input voltage is 24V. The battery voltage is 12V.

I realized that there was an issue with the soldering of the low-side MOSFET. Its source was not connected to the ground, preventing the PH-BTST capacitor from getting charged.

I also replaced the charger IC with a new one, and now it charges the battery.

However, I'm still facing an issue of charging happening (STAT1 is on) when no battery is connected. Any idea why that could be happening?

Thanks for your help, Mike.

Regards,

Sankar

0 Michael Emanuel35 over 3 years ago in reply to Sankar Manoj

TI__Mastermind 35135 points

Dear Sankar,

Please refer to the following table:

If the pin is off it is pulled high. When no battery is connected, you are most likely in battery absent which will have STAT1 and STAT2 off or pulled high.

Thanks,

Mike Emanuel

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BQ24630: STAT1 is on without battery connected, but does not charge