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diy iphone charger efficeny

jcm005

Feb 17, 2013
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ok i made my own iphone charger and it charges! Great! now I got a Question for yall.
If i used 1/2 watt pullup resistirs on the data lines instead of 1/8 watt, would that ruin the efficeny? also i used a 47kohm instead of 49.9k and 75k could this be a reason for a slow charge. If you neededd to know im using a max756 dc/dc step up. Please reply sorry for bad english and typos
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Increasing the wattage of the resistors will have no effect.

I would need to see the original schematic and then the modifications you made in order to figure out of the substitution is significant.
 

jcm005

Feb 17, 2013
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here ya go

usb4res500mA.gif


there you are
 

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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Well, the connections to the D+ and D- pins are totally different, so I expect the operation to likewise be totally different (in terms of the device recognising the capability of the charger)
 

jcm005

Feb 17, 2013
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Well, the connections to the D+ and D- pins are totally different, so I expect the operation to likewise be totally different (in terms of the device recognising the capability of the charger)

the device recognizes the charger so it charges but not at a great efficiency

LTC3401
if i used a ltc3401 would it charge faster. please look up the specs to that ic
thankyour
 

BobK

Jan 5, 2010
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Efficiency does not mean what you think it means. You might have a charger that charges the phone in one hour but is less efficient than one that charges it in two hours. Efficiency here means (energy put the battery) / (energy used by the charger).

Is this what you are asking, or are you asking for faster charge times?

Bob
 

jcm005

Feb 17, 2013
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Efficiency does not mean what you think it means. You might have a charger that charges the phone in one hour but is less efficient than one that charges it in two hours. Efficiency here means (energy put the battery) / (energy used by the charger).

Is this what you are asking, or are you asking for faster charge times?

Bob

yes but i want to be efficient energy and not like half ass of thats makes
sense
 

BobK

Jan 5, 2010
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Okay, I found the place where the diagrams you posted came from. These resistors on the D+ and D- lines apply only to Apple products, and they set voltages that determine how much current they will pull for charging. If you read it you will find that different values of resistor dividers will give you different charge rates.

http://www.sinfuliphone.com/showthread.php?t=31301

Bob
 
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