How to Charge Internal Battery & Use Device at Same Time ? help !

Discussion in 'The Projects Forum' started by offtherails2010, Dec 30, 2014.

  1. offtherails2010

    Thread Starter New Member

    Dec 31, 2011
    howdy all !

    okay so im trying to make a battery charging circuit with PCB boards found easily & cheaply on ebay (from china) and i wanted to know how the big boys enable their top line devices to be charged whilst being used.

    An example of this is any high-end rechargeable mouse, that can be plugged into USB cable, be charged and be used at the same time.

    So what im trying to get correct, is the power in my circuit, i dont want anything damaging the component PCB's in the loop, a picture is worth a thousand words, so here's a rough sketch of my circuit:

    [​IMG]Rechargeable Battery Circuit by offtherails2010, on Flickr

    My battery is a cell phone battery, namely the BST-33 from here:

    Charging Circuit:

    Step up/down PCB:

    iLuv Speaker:

    - This will power my little iLuv portable speaker that takes 3 AAA batteries, which never last long, are pretty useless in my humble opinion & are just plain annoying to charge in such an odd number of batteries lol

    - The internal Amp in the iLuv would be theoretically be connected to the output, 4.5v constant voltage from the step up/down boost PCB (which is from 3v to 6v input, upto 6v MAX output)

    - The battery has protection circuitry inside it, verified physically & the charging PCB also auto cuts off at 4.2v

    - not quite sure if ive got the diode the correct way in the sketch.

    - also the diode is a very low drop out of only 0.3V (or very near to that, need to look through my stock of SMD parts lol), SMD, so wont lose much voltage there.

    Finally the Question lol:

    Have i got this drawn correctly so that when charging the Lipo battery, i can still play the iLuv Speaker at the same time ?

    a great many thanks to any suggesstions, comments & help :)