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li-ion 3.5v inductive charging circuit

Discussion in 'General Electronics Discussion' started by sheldon williamson, Sep 18, 2014.

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  1. sheldon williamson

    sheldon williamson

    Sep 18, 2014
    Hello yall

    I'm trying to build a 3.5v inductive charging circuit for a small 3000ma batery that will power some lights that could also be used to charge your phone..

    I am using adafruits 3.5v inductive coils attached to a 110v ac wall plug in power adapter.

    the reciving end is attached to a 3000ma li-ion phone battery which is attached to 8feet of el wire and a micro usb port for your phone.

    i have been researching what it takes to charge a li-ion batter saftly and i have found several ic like this one

    to protect the circuit but I'm just not quite sure what all i need to make this legitamatly..

    what i would love to be able to do is add that ic to the out put of my transformer that then gets hooked into the inductive coils. so all my protection is in the charger and not the system I'm building to be charged. plus it seems simple to just add in this ic and be set and ready but unfortunatly i just don't know and can't find the answeres. I've seen where some need micro processors and so on.. would i need something like that?

    All i want to do is saftly charege this phone battery with this inductive coil.. I'm working on a prototype i would like to make into a product..

    thanks a ton and i hope i an find a simple solution to my problem :)
  2. Fish4Fun

    Fish4Fun So long, and Thanks for all the Fish!

    Aug 27, 2013
    Hey Sheldon! Welcome to EP!

    Hrmmm, where to start.....let's start with "inductive charger"....this is not really the right way to think about/discuss a charge controller, though I suppose it could be argued that many charge controllers use either an inductor or its first cousin a "transformer"....and both an "inductor" and a "transformer" have inductive impedance....but at the end of the day "inductive charger" is kind of like saying "self-powered automobile" when you simply mean "automobile" doesn't lend any clarity to your purpose...Furthermore, "power some lights that could also be used to charge your phone..." adds little to clarify your is the purpose of your cell-phone battery to charge a cell phone or is it to power some lights? Why would you use one cell-phone battery to charge another? OR do you want your charge controller to be able to charge both a cell-phone AND your cell-phone battery....Anyway, putting diction and sentence-structure aside I should first ask if this is a "project to learn about charge controllers" or if this is simply a "project to charge a battery".....If it is the latter then you are likely MUCH better off simply ordering a charge controller or re-purposing an existing charger....but before you go ordering anything or trying anything do a bit of might start here: or you might just Google "Lithium Battery Charging" and see where it leads you.....

    As far as the IC you selected....yes, it is designed specifically to do what you want to do...charge a Lithium based cell....that being said, a 10-MOSP package may prove difficult for you to actualize into a DIY circuit..the leads are 0.25mm (0.0098in) wide with only 0.3mm (0.01181in) spacing between give you some economy of scale 0.3mm = 300um = roughly 3 human hairs...the entire package is only ~3mm x 5mm....small enough that a good sneeze could send a pile of these chips off like a dust cloud....

    NO MATTER WHAT: Be very careful with DIY charge controllers and Lithium based batteries...incorrect charging can cause the battery to burst into flames or possibly even explode! I would NOT consider DIYing a Lithium Battery Charge Controller to be a suitable project for anyone not well-versed in the nuances of electronics. If you want to experiment with DIY charge controllers, start with Lead-Acid cells...they are very straight-forward, require little knowledge to build successfully and are relatively immune to many of the pitfalls involved in Lithium based battery charging.

    KrisBlueNZ likes this.
  3. sheldon williamson

    sheldon williamson

    Sep 18, 2014
    Last edited: Sep 19, 2014
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