• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 852 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Solar panel charger design

Tao Qian
Prodigy 20 points
Other Parts Discussed in Thread: BQ25895, BQ25703A, TIDA-01556

Hello,

I want to design a high efficient solar charging system for filed monitoring system. The power consumption of the system is about 5W and lithium-ion rechargeable battery is used to collected energy and support the system working 24 hour a day. To guarantee the system non-stop working around the year, I need to decide the battery capacity and power of solar panel. The high efficient charging system always help to get more power from sun. Any suggestion about the system design or available reference design is helpful. Thanks

  • 0
    TI__Mastermind 25800 points

    Hey Tao,

    We do have a reference design that is optimized for a single-cell application using our bq25895 charger.

    Please find the reference design here: http://www.ti.com/tool/TIDA-01556

    Now, you did mention your system will be consuming 5W of power. Is this a constant 5W throughout all 24 hours of the day? Or is this just peak current with down-time in between? 

    If it is constant 5W, you will likely want to consider a battery with enough capacity to handle the load when the panel cannot provide power (>=5Wh battery). Additionally, you will likely want to find a panel with at least 5W at a minimum, but likely more would be required as power can fluctuate (to lower values) throughout the day. 

    If your battery pack will be more than a single-cell, the above reference design may be modified to for one of our multi-cell capable charge controllers like the bq25703A. 

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Prodigy 20 points
    Hi Joel,

    Thanks for your helps.

    The system consumes 4~5W constantly. Now we tried BP220 (www.bixpower.com/.../bat-bp220.htm) with 223Whours capacity Li-on battery with charging circuit included and 60W solar panel. The result is not good. The batter only can be charged around 50% after whole sunny day and can't keep the system working for long time. I think the charge efficiency is the problem. We want to design the high efficient power harvesting system.

    The reference design you mentioned is not for sale. Do you testing board or demo kit for the design? BTW, for our application, we need 250~300wh battery to store the power for system on the field, what kind of battery cell you can recommend?

    Thanks

    Tao
  • 0 in reply to Tao Qian
    TI__Mastermind 25800 points
    Hey Tao,

    Do you have the characteristics of the 60W panel that would be connected (i.e. VOC, ISC, VMPP, VSC)?

    As far as the reference design, do note that it was created for single-cell low/medium power solar applications (<10W). The devices used in the design however can be ordered separately here:
    www.ti.com/.../BQ25895EVM-664
    www.ti.com/.../MSP-EXP430FR4133

    The hardware I2C pins of MSP430 Launchpad are used (P5.2, P5.3).

    However, for the battery capacity you linked in your post (223Wh), you may want to consider the bq25703A for a multi-cell battery application. This device is a charge controller, so you would select your switching FETs to optimize your power losses, current capability, operating voltage. The reference design code provided in TIDA-01556 can be modified to work with this charger.

    As far a battery selection, unfortunately we do not have a good references for battery vendors, and the selection itself would depend on how much power you would need to source and how much battery life you would like in your application. Your system requirements (when running solely on battery power) will determine what type of battery you will like.

    What is the application for your design? How will it be used in the field?


    Regards,
    Joel H