Li-Poly Battery Charger with MPPT or variable charge current

Dharmesh Joshi

Other Parts Discussed in Thread: BQ25798, BQ24650

I require a charge for a Li-Poly battery that will work well with a Solar panel. From my understanding, as the sunlight varies the charge current should also vary, otherwise, the voltage from the input would drop below the charger minimum working voltage? This would cause some form of pulse charging instead of a continuous charge.

Can you please recommend me what would be a suitable charger for such application?

Thank You

over 4 years ago

0 Jeff F over 4 years ago

TI__Guru**** 165886 points

Hi Dharmesh,

What is the VOC and ISC of the solar panel? What is the battery you are planning to charge?

Regards,

Jeff

0 Dharmesh Joshi over 4 years ago in reply to Jeff F

Expert 1895 points

Hi Jeff

The battery is a Li-Poly 4.2V 8000mAh

And panels we aim to use are Renogy 50 Watt 12 Volt Monocrystalline Solar Panel | Renogy Solar

Open-Circuit Voltage (Voc): 21.8V

Short-Circuit Current (Isc): 3.10A

0 Jeff F over 4 years ago in reply to Dharmesh Joshi

TI__Guru**** 165886 points

Hi Dharmesh,

I recommend the BQ25798.

Regards,

Jeff

0 Dharmesh Joshi over 4 years ago in reply to Jeff F

Expert 1895 points

Is there any solution without all th digital interface.

The aim is to design a standalone charger.

0 Jeff F over 4 years ago in reply to Dharmesh Joshi

TI__Guru**** 165886 points

Dharmesh,

The closest fit is BQ24650.

Regards,

Jeff

0 Dharmesh Joshi over 4 years ago in reply to Jeff F

Expert 1895 points

Thanks, I will read the datasheet. Just out curiosity is it possible to have automated dynamic MPPT rather then something that is set by a static value?

0 Jeff F over 4 years ago in reply to Dharmesh Joshi

TI__Guru**** 165886 points

Hi Dharmesh,

Not with BQ24650. However, for a given solar panel, the MPP % is fairly constant until very low light but does vary with temp. I suggest you read the 2 app notes below:

Regards,

Jeff

0 Dharmesh Joshi over 4 years ago in reply to Jeff F

Expert 1895 points

Thanks I will read the application notes.

If temperature compensation is included in the mppt that would be good. And I could add jumper settings for different solar panel types. This way mppt would be efficient on the pcb for all solar panel types.

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Li-Poly Battery Charger with MPPT or variable charge current