BQ25504: Battery not charging, MPPT disabled

Sophi

Prodigy 10 points

Part Number: BQ25504

Tool/software:

Hi - my battery isn't charging from the solar panel (SOLAR CELL 87.6MW 3.4V).

I've tried it with a 150mAh (starting at 3.507V) and a 500mAh LiPo battery (starting at 3.859V).

Each time the battery voltage seems to rise about 10mA but no further.

I measure 3.2V at VIN_DC.
MPPT is disabled.

I appreciate any ideas!

24 days ago

0 Michael Emanuel35 23 days ago

TI__Mastermind 34575 points

Hello,

The solar panel you are using is too high voltage. Please see the EC table, the max input voltage allowed for VIN_DC is 3 V.

Regards,

Mike Emanuel

0 Sophi 23 days ago in reply to Michael Emanuel35

Prodigy 10 points

Thanks Michael, that was very helpful.

The panel is rated open voltage 3.4V and voltage @ Pmpp of 2.2V.
I brought the setup inside, now reading VIN_DC of 2.68V and battery voltage jumped up by 5mA - not sure yet if it is charging or error factor in DVM.

I'll report back in a few hours.

0 Michael Emanuel35 23 days ago in reply to Sophi

TI__Mastermind 34575 points

Hello,

There is little valuable solar light to be absorbed inside. The VIN_DC dropped because the irradiance is lower. Please enable MPPT outside.

Regards,

Mike Emanuel

0 Sophi 23 days ago in reply to Michael Emanuel35

Prodigy 10 points

I didn't design the circuit to enable MPPT so I'm not sure I can enable it, the board is tiny!
Do you know why there's an option to disable MPPT?

0 Michael Emanuel35 20 days ago in reply to Sophi

TI__Mastermind 34575 points

Hello,

You need a resistor divider between VIN_DC, VOC_SAMP, and GND to enable MPPT. MPPT can be disabled if the user doesn't need it.

Regards,

Mike Emanuel

Power management

Power management forum

BQ25504: Battery not charging, MPPT disabled