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BQ25504: AC Application Question

Lucas Wolfe
Prodigy 30 points
Part Number: BQ25504

Hello,


I would like to use a varying electromagnetic energy harvester with a bridge rectifier as an input into the BQ25504 in order to charge a battery. I am unsure how to implement the MPPT feature of the BQ25504 with my electromagnetic energy harvester source. The data sheet says MPPT for solar panels is 80% but I am unsure of how this would change for an AC electromagnetic generator. Should I use a different MPPT percent or just disable MPPT completely?

Any help would be greatly appreciated.


Thanks!

  • 0
    Guru 13040 points

    Lucas,

    Sorry that I don't have the answer for your question, but as the subject is of particularly interesting to a project of mine as well, I wanted to leave a note here.

    I found an very basic but clear explanation to MPPT here. Basically what we want is to configure the charger to obtain the maximum possible power to a block of batteries, given a certain input voltage range.

    Would you care to share some information about the harvester you are planning to use? If we can see the expected output (both before and after the rectifier), posters might be able to provide a more assertive answer.

    Rgds

    Bruno

  • 0 in reply to Bruno Saraiva
    Prodigy 30 points
    Bruno,

    I wanted to thank you for your response as well as the note on MPPT. I do not have information on the harvester output at the moment but I intend to do some tests and will have some numbers soon.

    I do know that the output of this harvester will be very irregular and most likely very small (hence my interest in the bq25504). I will get some numbers soon!

    Thanks again,

    Lucas
  • 0
    Prodigy 30 points
    Just some info on my energy harvester. The device itself is basically a magnet oscillating through a coil of wire. At the output of the rectifier, I am getting anywhere between 200mV up to around 6 or 7V (these upper values will not occur often, if at all in the application the harvester will be used for). I am anticipating the output of the rectifier to often be below 5V.

    I am still unsure of what MPPT% to use for the BQ25504 device though.

    Thanks again,

    Lucas