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    Charging from USB wall adapters, how to control current & not harm the wall adapter ?

    Hello
    I have a battery of 2 Li-Ion cells = 7.4v
    To charge the battery i use the MP26123 IC charger
    I want to charge it from USB wall adapter
    For that i connected a booster that output 10v to MP26123 input
    The issue is how to control the switching current from the wall adapter
    If i set the battery charging current to 1A - it means the booster will draw approx. 2.35A (Eff 85%)
    But if someone will connect it to 1A wall charger it will not work (maybe the charger will be damaged)
    Any ideas?

    ThanksClick image for larger version. 

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    Last edited by JuniorEE; 7th December 2017 at 07:49. Reason: Add picture

    •   Alt7th December 2017, 07:31

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  2. #2
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    Re: Charging from USB wall adapters, how to control current & not harm the wall adapt

    Idea: use the appropriate size wall adapter. What else could you possibly do? You probably won't damage an undersized adapter, they (should) have current/over temp limiting.

    - - - Updated - - -

    Idea: use the appropriate size wall adapter. What else could you possibly do? You probably won't damage an undersized adapter, they (should) have current/over temp limiting.



    •   Alt7th December 2017, 15:12

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    Re: Charging from USB wall adapters, how to control current & not harm the wall adapt

    I do not want to limit the customer to charge from 2A or 3A wall charger....
    I want to be able to charge wise (dependng on the user charger capabilities)



    •   Alt7th December 2017, 15:33

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    Re: Charging from USB wall adapters, how to control current & not harm the wall adapt

    Hi,

    then you need to read out the wall adapter capabilities.
    This can be determined by reading out the D+ and D- voltages coming from the wall adapter.

    Search the internet for "USB DCD ID"

    Klaus
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  5. #5
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    Re: Charging from USB wall adapters, how to control current & not harm the wall adapt

    Hi Klaus

    Do you mean to USB battery charging sepcification ? DCP, CDP, SDP ?
    Are there dedicated Li Ion 2cell chargers with USB detection capability ?



    •   Alt11th December 2017, 13:37

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  6. #6
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    Re: Charging from USB wall adapters, how to control current & not harm the wall adapt

    Hi,

    Sorry I meant "Search the internet for "USB DCP ID""
    DCP = dedicated charging port...
    ... and this leads to battery charging
    ... and how wall adapter shows itīs current capabilities.

    You are free to use other search phrases like "USB battery charging". Luck you - there are internet search engines. I remember times where there was no internet at all.

    Klaus
    Please donīt contact me via PM, because there is no time to response to them. Thank you.



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