# Kemo M172 USB dynamo charger modding



## ktronik (Dec 23, 2006)

HI everyone, here is some hardware info on modding the Kemo M172n USB dynamo charger, its largish but quite a cheap USB charger made in germany, that I have modded to 930mA output...attached are some pics of how its done...

Basically I removed the switch at top, or if your careful, you can, once switch is loose up top, clip the 3 switch terminals, and re-use that switch...however, you need to bridge the contacts left on the main board, (left by switch) so the its allways in USB mode...so bridge center contact to right contact of switch (at board level)....now its always in USB mode, we simply are adding a 'booster cap',(50v 100uf bipolar) IN SERIES with the input...as per circuit diagram...the main switch now offers the boost cap, or bypass the boost cap to offer 500mA or 930mA @5v USB output,. from any Shimano, SON or SP hub. Questions are fine...

if you want a OFF, in the mix just use a SPDT switch w center OFF...


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## Guus Welter (Apr 9, 2014)

Hello ktronic,

I like what you did, boosting the M172n!
Does it work so far?

why should you want to change between 500Ma and 950Ma? Is it not possible just to put the booster between 2 contacts of the switch? (Which contacts would that be)
Last thing: is the system now protected against overcharging, power etc?

Like to hear from you!
Regards
Guus Welter


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## ktronik (Dec 23, 2006)

Hey Guus,

No reason to change from 500mA to 900mA, as the device would just take / pull what it needs...however, if the tiny cap that fitted, when POOF, then you could by-pass with the switch and still keep going...

the unit is made to run at 800mA...but only offers 500mA on my SP hub...so modding to 930mA should be fine, however not done any long term testing....

each USB device has its own protection....as the kemo has no battery inside, it need only to offer 5v out....

hope this helps

K


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