Instructables

DIY USB dynamo charger and AA battery charger.

Picture of DIY USB dynamo charger and AA battery charger.
USBchargerPCB.jpg

DIY USB charger using AA batteries....

Its a very simple unit....Dynamo goes via a rectifier and charges up the AA 6 cell (7.2v) NIMH pack (marked DC in pic)

AA battery's make the hub lock to use charging voltage of battery...without a booster cap the have a max charge rate of 500mA from hub

For ease of use, I bought a 5v regulator...it outputs 5v @ max 600mA...you can run 2 of them if needed.
http://www.pololu.com/product/2107

when you flick the switch, the battery stops charging and pushes it power to run the 5v reg (for USB output)

I run a little voltage readout to tell me where the voltage is at...
http://www.hobbyking.com/hobbyking/store/__7224__Hobby_King_Battery_Monitor_2S_EU_warehouse_.html

there is a buzzer on board but I remove that, so it just the LED that let me know the voltage for when they are charged...

7.2v battery pack will reach its empty point, just as the 5v REG falls OUT of regulation and turns OFF, thus stopping the batteries from being over drained.

you need to keep an eye on the voltage LEDs, for when they are charged...however 4-6hr and they will be done...

AS the AC from the hub can harm electronics, its made to be CHARGE OR RUN....

I have made a few PCBs for others to try...its very easy to do, with only basic soldering needed....

you can also use 4x NI-ZN batterys as the voltage will be very close....

got a few PCB is anyone wants to try it out...;)
craftclarity6 months ago
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