Ham radio battery charger mod

• DISCLAIMER: I DO ELECTRONICS AND 3D DESIGN SOLELY AS A HOBBY. THERE COULD BE ERRORS THAT CAN RESULT IN ALL KINDS OF DAMAGE. USE THESE DESIGNS AT YOUR OWN RISK.
• This design is released under Creative Commons Zero (CC0) license.
• Authors:
  • Svjatoslav Agejenko
    • Homepage: https://svjatoslav.eu
    • Email: svjatoslav@svjatoslav.eu
  • Valeria Agejenko
• See also:
  • Other physical projects in this repository
  • Other projects hosted at svjatoslav.eu

Warning: this project is quite hacky. It requires breaking original charger to get required critical charger part. Instructions are not very detailed. Only describe the overall idea. Do not attempt to reproduce this unless you exactly know what you are doing.

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I have Baofeng GT-STP and Baofeng UV-82 radios. Their batteries have slightly different geometry, so chargers are physically not compatible. Also each changer comes with its own power adapter to plug into wall power socket. Electrically batteries are apparently compatible.

By building this battery charger I solved 2 issues:

• It can charge batteries for both radios. Is physically and electrically compatible to both models.
• Wall adapter is no longer needed. Now it is powered by USB connector from computer.

Body ignores small physical differences between batteries and both can be plugged in.

Front side contains critical fragment of the original changer circuit board to drive the actual battery charging.

Back side contains voltage upstep converter that is tuned to convert 5V USB input to 10V output that is required by the charger.

Voltage upstep converter can produce significant voltage ripples/impulses that travel backwards to the power source and forward to the changer. To reduce this effect, there are capacitors and inductor.

Front and back sides are connected by wiring at the bottom. Also there are screws to hold original Baofeng charger pins/springs that connect to the battery.

After assembly is complete, back, front and bottom parts are sealed with lid: