Objective comparison between emergency usb chargers

Laszlo KREKACS laszlo.krekacs.list at gmail.com
Thu Aug 13 22:42:34 CEST 2009


I have already bought 3 different usb chargers, and I can test them.
I also just ordered two additional chargers from ebay.

So I would like to know any details, how to make objective (neutral)
comparison between them. Would like to summarize my test
data on a dedicated wiki page for everyone's benefit.

Im on om2009t5, so maybe the sys paths are different, so
would like some pointers where to look and what is exactly
the differences between 2.6.28, 2.6.29 and 2.6.30.

 How to measure charging data, how to automatically
resume (from suspend) check the charging datas and
suspend again?
How to measure voltages? (output voltage of
one charger without load is 6.7V)

How works the different charging modes? (100,500,1000mA)
Is it fix? So if I set 500mA, and the charger can deliver only
340mA, can the charger overheat? Can I charge with 340mA
or only with distinct 100, 500 and 1000mA?

I also read on the wikipage, that If I set the charging current
higher what my charger can deliver, I can destroy not only
the charger but the freerunner itself too. (is it the case?
some technical explanation?)

How the current limitation works? So if I set 1000mA, and
the charger can only deliver 500mA, what will exactly happen?
(how the current limitation works inside the freerunner?)

I hope we can collaborate, collect useful data and publicate
them. Im very tired all these cheap half-finished electrical
devices (I can only charge 27% from a 3500mAh 3.7V
accumulator! It is insane!)

I also want to collect the *efficiency* of the charger backed up
with some measured data.

For example MintyBoost site have some detailed measurement
how the efficiency is of the Mintyboost (from 60-80% depending of
the charging state of the battery).

My goal is: having a usb charger what is capable to recharge
two or three times the FreeRunner.

Best regards,

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