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

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JuniorEE

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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?

Thanks IMG_0035.JPG
 
Last edited:

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.
 

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)
 

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
 

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 ?
 

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 it´s 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
 

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